Patent Publication Number: US-9884813-B1

Title: Pharmaceutically acceptable salts of B-guanidinopropionic acid with improved properties and uses thereof

Description:
BACKGROUND 
     β-Guanidinopropionic acid (β-GPA), also referred to as guanidinopropionic acid, beta-guanidinopropionic acid or, N-(aminoiminomethyl)-beta-alanine is a creatine analog. Studies on animals (rats, monkeys, hamsters) show that acidic guanidine derivatives such as β-GPA can ameliorate hyperglycemia in animal models of noninsulin-dependent diabetes. Accordingly, it is sometimes used as a dietary supplement in diabetic patients to regulate blood sugar levels. β-GPA is a white crystalline powder that is highly soluble in water (&gt;50 mg/mL). 
     β-GPA has recently been found to be effective for the suppression of metastasis, particularly liver metastasis in gastrointestinal cancers, e.g., see International Patent Publication WO2014/071067. However, due to the physical properties of β-GPA in the solid state, e.g., poor flow properties and compressibility, there exists a need for β-GPA salts and formulations with improved physical properties and handling characteristics. 
     SUMMARY OF THE INVENTION 
     The present invention features new pharmaceutical salts of β-GPA which exhibit improved physical properties. In particular, the invention features salts of β-GPA with improved flow properties (e.g., improved Carr&#39;s index and/or Hausner ratio), such as fumarate salts, succinate salts, and oxalate salts. The invention also features pharmaceutical compositions including a pharmaceutically effective amount of one or more salts of β-GPA, as well as methods of treating cancer including administration of a formulation including a β-GPA salt of the invention to a subject in need thereof. 
     Accordingly, in a first aspect, the invention features a pharmaceutically acceptable salt of 6-guanidinopropionic acid having a Carr&#39;s Index of less than 20 (e.g., less than 15, less than 10, less than 6) and/or a Hausner ratio of less than 1.25 (e.g., less than 1.2, less than 1.15, less than 1.1). In some embodiments, the pharmaceutically acceptable salt is a salt of a dicarboxylic acid (e.g., fumaric acid, succinic acid, or oxalic acid). In some embodiments, the pharmaceutically acceptable salt is a fumarate salt (e.g., a 2:1 fumarate salt), a succinate salt (e.g., a 2:1 succinate salt), or an oxalate salt (e.g., a 1:1 oxalate salt). 
     In some embodiments, the pharmaceutically acceptable salt is crystalline (e.g., a 2:1 fumarate salt with platelet-like crystal morphology). In some embodiments, the pharmaceutically acceptable salt includes less than 40% by weight (e.g., less than 30%, less than 20%, less than 10%, less than 5%, less than 1% or between 30-40%, 25-35%, 20-30%, 15-25%, 10-20%, 5-15%, 1-10%) of amorphous compound. In some embodiments, the pharmaceutically acceptable salt is substantially free of amorphous compound. In some embodiments, the pharmaceutically acceptable salt is substantially free of any other salt or crystal form of β-GPA. 
     In some embodiments, the pharmaceutically acceptable salt is a 2:1 fumarate salt. In some embodiments, the pharmaceutically acceptable salt has an endothermic onset at about 251° C. (e.g., from 248° C. to 253° C., 249° C. to 254° C., 250° C. to 255° C., 248° C. to 255° C.) in differential scanning calorimetry (DSC) profile. In some embodiments, the pharmaceutically acceptable salt has an endothermic onset at about 187° C. (e.g., from 185° C. to 188° C., 186° C. to 189° C., 184° C. to 187° C., 184° C. to 189° C.) in differential scanning calorimetry (DSC) profile. In some embodiments, the pharmaceutically acceptable salt has two endothermic onsets in differential scanning calorimetry (DSC) profile. In some embodiments, the pharmaceutically acceptable salt has a loss of weight from 31° C. to 140° C. of less than 5% (e.g., less than 4%, less than 3%, less than 2%, less than 1%) as measured by thermal gravimetric analysis. 
     In some embodiments, the pharmaceutically acceptable salt is a 1:1 fumarate salt. In some embodiments, the pharmaceutically acceptable salt has an endothermic onset at about 171° C. (e.g., from 169° C. to 173° C., 170° C. to 173° C., 169° C. to 172° C., 170° C. to 172° C.) in differential scanning calorimetry (DSC) profile. In some embodiments, the pharmaceutically acceptable salt has a loss of weight from 31° C. to 140° C. of less than 5% (e.g., less than 4%, less than 3%, less than 2%, less than 1%) as measured by thermal gravimetric analysis. 
     In some embodiments, the pharmaceutically acceptable salt has at least one peak at diffraction angle 2θ (°) of 20±0.5 as measured by X-ray powder diffractometry. In some embodiments, the pharmaceutically acceptable salt further has at least one peak at diffraction angle 2θ (°) of 20±0.5, 20.5±0.5, and/or 23±0.5 as measured by X-ray powder diffractometry. In some embodiments, the pharmaceutically acceptable salt has one or more (e.g., two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, nine or more, ten or more, eleven or more, twelve or more, thirteen or more, fourteen or more) peaks listed in Table 1 as measured by X-ray diffractometry or calculated from X-ray diffractometry. In some embodiments, the pharmaceutically acceptable salt has all of the peaks listed in Table 1 as measured by X-ray diffractometry or calculated from X-ray diffractometry. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 XRPD peak list for the 1:1 fumarate salt of β-GPA 
               
            
           
           
               
               
               
            
               
                   
                 2θ (°) 
                 Intensity 
               
               
                   
               
            
           
           
               
               
               
            
               
                   
                 11.78 
                 5.5 
               
               
                   
                 13.95 
                 6.0 
               
               
                   
                 17.42 
                 6.4 
               
               
                   
                 19.22 
                 12.5 
               
               
                   
                 19.68 
                 21.1 
               
               
                   
                 20.02 
                 8.4 
               
               
                   
                 20.58 
                 27.4 
               
               
                   
                 21.01 
                 6.3 
               
               
                   
                 22.87 
                 22.4 
               
               
                   
                 23.74 
                 6.4 
               
               
                   
                 24.74 
                 5.5 
               
               
                   
                 25.57 
                 5.4 
               
               
                   
                 26.74 
                 100 
               
               
                   
                 28.84 
                 12.3 
               
               
                   
                 29.48 
                 7.1 
               
               
                   
               
            
           
         
       
     
     In some embodiments, the pharmaceutically acceptable salt has one or more (e.g., two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, nine or more, ten or more, eleven or more, twelve or more, thirteen or more, fourteen or more) peaks listed in Table 2 as measured by X-ray diffractometry or calculated from X-ray diffractometry. In some embodiments, the pharmaceutically acceptable salt has all of the peaks listed in Table 2 as measured by X-ray diffractometry or calculated from X-ray diffractometry. 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 XRPD peak list for the 2:1 fumarate salt of β-GPA 
               
            
           
           
               
               
               
            
               
                   
                 2θ (°) 
                 Intensity 
               
               
                   
               
            
           
           
               
               
               
            
               
                   
                 17.47 
                 1.8 
               
               
                   
                 19.26 
                 6.8 
               
               
                   
                 19.71 
                 3.3 
               
               
                   
                 20.67 
                 5.3 
               
               
                   
                 22.90 
                 9.3 
               
               
                   
                 25.91 
                 2.5 
               
               
                   
                 26.78 
                 100 
               
               
                   
                 27.51 
                 3.2 
               
               
                   
                 28.73 
                 2.7 
               
               
                   
                 29.12 
                 1.8 
               
               
                   
                 31.16 
                 2.5 
               
               
                   
                 33.04 
                 1.7 
               
               
                   
                 33.98 
                 3.5 
               
               
                   
                 35.27 
                 3.1 
               
               
                   
                 39.05 
                 2.7 
               
               
                   
                 23.82 
                 2.9 
               
               
                   
                 24.09 
                 3.2 
               
               
                   
                 20.97 
                 5.7 
               
               
                   
               
            
           
         
       
     
     In some embodiments, the pharmaceutically acceptable salt when analyzed by single crystal X-ray diffractometry has a unit cell of the space group P 2 1 /n, having dimensions of a=about 12.4541 Å, b=about 9.5447 Å, c=about 14.4013 Å and a=about 90°, β3=about 100.5°, γ=about 90° and/or a cell volume of about 1683.39 Å 3 . 
     In some embodiments, the pharmaceutically acceptable salt has at least one peak at 3300±1 cm −1  as measured by Raman spectroscopy. In some embodiments, the pharmaceutically acceptable salt has at least one peak at 3188±1 cm −1  as measured by Raman spectroscopy. In some embodiments, the pharmaceutically acceptable salt has at least one peak at 3049±1 cm −1  as measured by Raman spectroscopy. In some embodiments, the pharmaceutically acceptable salt has at least one peak at 2941±1 cm −1  as measured by Raman spectroscopy. In some embodiments, the pharmaceutically acceptable salt has at least one peak at 2886±1 cm −1  as measured by Raman spectroscopy. In some embodiments, the pharmaceutically acceptable salt has at least one peak at 1713±1 cm −1  as measured by Raman spectroscopy. In some embodiments, the pharmaceutically acceptable salt has at least one peak at 1653±1 cm −1  as measured by Raman spectroscopy. In some embodiments, the pharmaceutically acceptable salt has at least one peak at 1483±1 cm −1  as measured by Raman spectroscopy. In some embodiments, the pharmaceutically acceptable salt has at least one peak at 1421±1 cm −1  as measured by Raman spectroscopy. In some embodiments, the pharmaceutically acceptable salt has at least one peak at 1382±1 cm −1  as measured by Raman spectroscopy. In some embodiments, the pharmaceutically acceptable salt has at least one peak at 1305±1 cm −1  as measured by Raman spectroscopy. In some embodiments, the pharmaceutically acceptable salt has at least one peak at 1268±1 cm −1  as measured by Raman spectroscopy. In some embodiments, the pharmaceutically acceptable salt has at least one peak at 1190±1 cm −1  as measured by Raman spectroscopy. In some embodiments, the pharmaceutically acceptable salt has at least one peak at 1084±1 cm −1  as measured by Raman spectroscopy. In some embodiments, the pharmaceutically acceptable salt has at least one peak at 997±1 cm −1  as measured by Raman spectroscopy. In some embodiments, the pharmaceutically acceptable salt has at least one peak at 896±1 cm −1  as measured by Raman spectroscopy. In some embodiments, the pharmaceutically acceptable salt has at least one peak at 681±1 cm −1  as measured by Raman spectroscopy. In some embodiments, the pharmaceutically acceptable salt has at least one peak at 625±1 cm −1  as measured by Raman spectroscopy. In some embodiments, the pharmaceutically acceptable salt has at least one peak at 555±1 cm −1  as measured by Raman spectroscopy. In some embodiments, the pharmaceutically acceptable salt has at least one peak at 486±1 cm −1  as measured by Raman spectroscopy. In some embodiments, the pharmaceutically acceptable salt has one or more (e.g., two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, nine or more, ten or more, eleven or more, twelve or more, thirteen or more, fourteen or more) peaks listed in Table 3 as measured by Raman spectroscopy. In some embodiments, the pharmaceutically acceptable salt has all of the peaks listed in Table 3 as measured by Raman spectroscopy. 
     
       
         
           
               
             
               
                 TABLE 3 
               
               
                   
               
               
                 Raman spectra peak list for the 2:1 fumarate salt of β-GPA 
               
               
                 Raman Shift (cm-1) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
            
               
                 3300.48 
               
               
                 3188.58 
               
               
                 3049.73 
               
               
                 2941.74 
               
               
                 2886.78 
               
               
                 1713.28 
               
               
                 1653.49 
               
               
                 1483.79 
               
               
                 1421.11 
               
               
                 1382.54 
               
               
                 1305.4 
               
               
                 1268.76 
               
               
                 1190.66 
               
               
                 1084.59 
               
               
                 997.81 
               
               
                 896.56 
               
               
                 681.53 
               
               
                 625.6 
               
               
                 555.21 
               
               
                 486.79 
               
               
                   
               
            
           
         
       
     
     In some embodiments, the pharmaceutically acceptable salt is a 1:1 oxalate salt. In some embodiments, the pharmaceutically acceptable salt has at least one peak at diffraction angle 2θ (°) of 27.5±0.5 as measured by X-ray powder diffractometry. In some embodiments, the pharmaceutically acceptable salt has one or more (e.g., two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, nine or more, ten or more, eleven or more, twelve or more, thirteen or more, fourteen or more) peaks listed in Table 4. In some embodiments, the pharmaceutically acceptable salt has all of the peaks listed in Table 4 as measured by X-ray powder diffractometry. 
     
       
         
           
               
             
               
                 TABLE 4 
               
             
            
               
                   
               
               
                 XRPD peak list for the 1:1 oxalate salt of β-GPA 
               
            
           
           
               
               
               
            
               
                   
                 Angle (2θ) 
                   
               
               
                   
                 degree 
                 Intensity % 
               
               
                   
               
            
           
           
               
               
               
            
               
                   
                 10.66 
                 2.1 
               
               
                   
                 14.36 
                 1.7 
               
               
                   
                 15.26 
                 1.8 
               
               
                   
                 17.79 
                 2.0 
               
               
                   
                 20.24 
                 2.8 
               
               
                   
                 20.78 
                 1.8 
               
               
                   
                 23.69 
                 4.0 
               
               
                   
                 26.60 
                 1.8 
               
               
                   
                 27.45 
                 100.0 
               
               
                   
                 31.50 
                 1.7 
               
               
                   
                 33.62 
                 1.9 
               
               
                   
                 34.94 
                 1.8 
               
               
                   
                 35.76 
                 1.7 
               
               
                   
                 36.69 
                 1.6 
               
               
                   
                 37.23 
                 1.9 
               
               
                   
               
            
           
         
       
     
     In some embodiments, the pharmaceutically acceptable salt is a 2:1 succinate salt. In some embodiments, the pharmaceutically acceptable salt has at least one peak at diffraction angle 2θ (°) of 27±0.5 as measured by X-ray powder diffractometry. In some embodiments, the pharmaceutically acceptable salt has one or more (e.g., two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, nine or more, ten or more, eleven or more, twelve or more, thirteen or more, fourteen or more) peaks listed in Table 5. In some embodiments, the pharmaceutically acceptable salt has all of the peaks listed in Table 5 as measured by X-ray powder diffractometry. 
     
       
         
           
               
             
               
                 TABLE 5 
               
             
            
               
                   
               
               
                 XRPD peak list for the 2:1 succinate salt of β-GPA 
               
            
           
           
               
               
               
            
               
                   
                 Angle (2θ) 
                   
               
               
                   
                 degree 
                 Intensity % 
               
               
                   
               
            
           
           
               
               
               
            
               
                   
                  4.87 
                 3.9 
               
               
                   
                 16.29 
                 4.4 
               
               
                   
                 19.99 
                 29.3 
               
               
                   
                 20.62 
                 14.8 
               
               
                   
                 22.73 
                 3.9 
               
               
                   
                 23.13 
                 4.5 
               
               
                   
                 25.60 
                 4.5 
               
               
                   
                 26.23 
                 4.5 
               
               
                   
                 26.70 
                 100.0 
               
               
                   
                 27.26 
                 12.4 
               
               
                   
                 31.32 
                 4.4 
               
               
                   
                 34.24 
                 4.0 
               
               
                   
                 35.19 
                 4.6 
               
               
                   
                 36.41 
                 4.3 
               
               
                   
                 38.30 
                 5.6 
               
               
                   
               
            
           
         
       
     
     In another aspect, the invention features a composition (e.g., an aqueous composition) including any of the foregoing pharmaceutically acceptable salts and a pharmaceutically acceptable excipient. In some embodiments, the pharmaceutically acceptable salt contains less than 10% by weight (e.g., less than 5%, less than 1%) of amorphous compound. In some embodiments, the pharmaceutically acceptable salt is substantially free of amorphous compound. 
     In another aspect, the invention features a composition (e.g., an aqueous composition) including the fumarate salt of β-guanidinopropionic acid, wherein at least 80% (at least 85%, at least 90%, at least 95%, at least 99%) of the fumarate salt of β-guanidinopropionic acid is a 2:1 salt (e.g., wherein the composition is substantially free of the 1:1 fumarate salt of β-guanidinopropionic acid) and a pharmaceutically acceptable excipient. 
     In some embodiments of any of the foregoing compositions, the pharmaceutically acceptable excipient includes 1,3-butanediol, mannitol, water, Ringer&#39;s solution, or isotonic sodium chloride solution. In some embodiments of any of the foregoing compositions, the composition is formulated for intravenous infusion. 
     In another aspect, the invention features a method for treating cancer (e.g., gastrointestinal cancer such as colon cancer or gastric cancer, pancreatic cancer, liver cancer, breast cancer, prostate cancer, lung cancer, and melanoma) in a subject in need thereof, including administering to the subject an effective amount of any of the foregoing pharmaceutically acceptable salts or compositions. 
     In another aspect, the invention features a method for treating metastatic cancer (e.g., metastatic gastrointestinal cancer such as colon cancer or gastric cancer) in a subject in need thereof, including administering to the subject an effective amount of any of the foregoing pharmaceutically acceptable salts or compositions. In some embodiments, the effective amount includes an amount effective to suppress metastatic colonization (e.g., metastatic colonization in the liver) of the cancer (e.g., gastrointestinal cancer such as colorectal cancer or gastric cancer). 
     In another aspect, the invention features a method for treating cancer (e.g., gastrointestinal cancer such as colon cancer or gastric cancer) in a subject in need thereof, comprising injecting into the subject an effective amount of an aqueous composition comprising any of the foregoing pharmaceutically acceptable salts and a pharmaceutically acceptable excipient. In some embodiments, the cancer is metastatic cancer. In some embodiments, the effective amount is an amount effective to suppress metastatic colonization of the cancer. 
     In another aspect, the invention features a method of treating metastatic cancer (e.g., gastrointestinal cancer such as colorectal cancer, esophageal cancer, or gastric cancer, pancreatic cancer, liver cancer, breast cancer, prostate cancer, lung cancer, and melanoma) in a subject in need thereof comprising: (a) providing a subject identified to have, or to be at risk of having, metastatic cancer on the basis of the expression level of miR-483-5p and/or miR-551a is below a predetermined reference value or the expression level of CKB and/or SLC6a8 is above a predetermined reference value; and (b) administering to the subject an effective amount of any of the foregoing pharmaceutically acceptable salt or compositions. 
     In some embodiments any of the foregoing methods further include administering an additional therapy (e.g., an additional therapeutic agent) to the subject. In some embodiments, the additional therapy is a therapeutic agent such as cyclocreatine, a RNAi agent, a nucleic acid, a vector, 5-fluorouracil, Oxaliplatin, Irinotecan, Capecitabine, Gemcitabine, Cetuximab, Taxol, Avastin, folinic acid (leucovorin), Regorafenib, Zaltrap, topoisomerase I inhibitors, NKTR-102, Tivantinib, PX-866, Sorafenib, Linifanib, kinase inhibitors, Telatinib, XL281 (BMS-908662), Robatumumab, or IGF1-R inhibitors. 
     In another aspect, the invention features a method of producing a pharmaceutically acceptable 1:1 fumarate salt of β-guanidinopropionic acid. This method includes combining β-guanidinopropionic acid and fumaric acid in an amount sufficient to produce a pharmaceutically acceptable 1:1 fumarate salt of β-guanidinopropionic acid. In some embodiments, the method includes dissolving the β-guanidinopropionic acid and the fumaric acid in a solvent and the 1:1 fumarate salt of β-guanidinopropionic acid precipitates from the solvent. In some embodiments, the method further includes recrystallization of the 1:1 fumarate salt of β-guanidinopropionic acid. 
     In another aspect, the invention features a method of producing a pharmaceutically acceptable 2:1 fumarate salt of β-guanidinopropionic acid. This method includes combining β-guanidinopropionic acid and fumaric acid in an amount sufficient to produce a pharmaceutically acceptable 2:1 fumarate salt of β-guanidinopropionic acid. In some embodiments, the method includes dissolving the β-guanidinopropionic acid and the fumaric acid in a solvent and the 2:1 fumarate salt of β-guanidinopropionic acid precipitates from the solvent. In some embodiments, the method further includes recrystallization of the 2:1 fumarate salt of β-guanidinopropionic acid. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an image depicting X-ray powder diffraction (XRPD) pattern obtained for a crystalline form of the 1:1 fumarate salt of β-GPA. 
         FIG. 2  is an image depicting X-ray powder diffraction (XRPD) pattern obtained for a crystalline form of β-GPA. 
         FIG. 3  is an image of β-GPA crystals under a polarized microscope. 
         FIG. 4  is an image depicting a DSC thermogram obtained for a crystalline form of β-GPA. 
         FIG. 5  is an image depicting TGA analysis obtained for a crystalline form of β-GPA. 
         FIG. 6  is an image depicting a  1 H NMR spectra of a crystalline form β-GPA. 
         FIG. 7  is an image depicting a DVS analysis for a crystalline form of β-GPA. 
         FIG. 8  is an image depicting X-ray powder diffraction (XRPD) pattern obtained for a crystalline form of the 1:1 hydrochloride salt of β-GPA. 
         FIG. 9  is an image depicting X-ray powder diffraction (XRPD) pattern obtained for a crystalline form of the 1:1 maleate salt of β-GPA. 
         FIG. 10  is an image depicting X-ray powder diffraction (XRPD) pattern obtained for a crystalline form of the 1:1 fumarate salt of β-GPA. 
         FIG. 11  is an image depicting X-ray powder diffraction (XRPD) pattern obtained for a crystalline form of the 1:1 L-malic acid salt of β-GPA. 
         FIG. 12  is an image depicting X-ray powder diffraction (XRPD) pattern obtained for a crystalline form of the 2:1 succinate salt of β-GPA. 
         FIG. 13  is an image depicting X-ray powder diffraction (XRPD) pattern obtained for a crystalline form of the 1:1 oxalate salt of β-GPA. 
         FIG. 14  is an image depicting X-ray powder diffraction (XRPD) pattern obtained for a crystalline form of the 2:1 maleate salt of β-GPA. 
         FIG. 15  is an image depicting a  1 H NMR spectra of a crystalline form of the 2:1 maleate salt of β-GPA. 
         FIG. 16  is an image depicting a DSC thermogram obtained for a crystalline form of the 1:1 hydrochloride salt of β-GPA. 
         FIG. 17  is an image of a crystalline form of the 1:1 hydrochloride salt of β-GPA by hot stage microscopy. 
         FIG. 18  is an image depicting a DSC thermogram obtained for a crystalline form of the 1:1 maleate salt of β-GPA. 
         FIG. 19  is an image depicting a DSC thermogram obtained for a crystalline form of the 1:1 fumarate salt of β-GPA. 
         FIG. 20  is an image depicting TGA analysis obtained for a crystalline form of the 1:1 fumarate salt of β-GPA. 
         FIG. 21  is an image depicting a  1 H NMR spectra of a crystalline form of the 1:1 fumarate salt of β-GPA. 
         FIG. 22  is an image depicting a DSC thermogram obtained for a crystalline form of the 2:1 succinate salt of β-GPA. 
         FIG. 23  is an image of a crystalline form of the 2:1 succinate salt of β-GPA by hot stage microscopy. 
         FIG. 24  is an image depicting TGA analysis obtained for a crystalline form of the 2:1 succinate salt of β-GPA. 
         FIG. 25  is an image depicting a  1 H NMR spectra of a crystalline form of the 2:1 succinate salt of β-GPA. 
         FIG. 26  is an image depicting a DSC thermogram obtained for a crystalline form of the 1:1 oxalate salt of β-GPA. 
         FIG. 27  is an image depicting TGA analysis obtained for a crystalline form of the 1:1 oxalate salt of β-GPA. 
         FIG. 28  is an image depicting a  1 H NMR spectra of a crystalline form of the 1:1 oxalate salt of β-GPA. 
         FIG. 29A - FIG. 29J  are images of crystalline forms of β-GPA salts.  FIG. 29A ) 1:1 hydrochloride salt of β-GPA;  FIG. 29B ) 1:1 phosphate salt of β-GPA;  FIG. 29C ) 1:1 mesylate salt of β-GPA;  FIG. 29D ) 1:1 maleate salt of β-GPA;  FIG. 29E ) 1:1 maleate of β-GPA;  FIG. 29F ) 2:1 maleate salt of β-GPA;  FIG. 29G ) 1:1 fumarate salt of β-GPA;  FIG. 29H ) 1:1 malate salt of β-GPA;  FIG. 29I )  2 : 1  succinate salt of β-GPA; and  FIG. 29J ) 1:1 oxalate salt of β-GPA. 
         FIG. 30  is an image depicting the rod-like crystal morphology of 1:1 fumarate salt of β-GPA (Pattern 7A). 
         FIG. 31  is an image depicting a comparison of XRPD analysis before and after DVS of 1:1 fumarate salt of β-GPA (Pattern 7A). 
         FIG. 32  is an image depicting X-ray powder diffraction (XRPD) pattern obtained for a crystalline form of the 1:1 fumarate salt of β-GPA after slow evaporation of solvent. 
         FIG. 33  is an image depicting an X-ray powder diffraction (XRPD) pattern obtained for a crystalline form of the 1:1 fumarate salt of β-GPA after slurry experiment in tetrahydrofuran:water (1:1) for 48 hours. 
         FIG. 34  is an image depicting X-ray powder diffraction (XRPD) pattern obtained for a polymorph of the 2:1 fumarate salt of β-GPA (Pattern 7C). 
         FIG. 35  is an image depicting a  1 H NMR spectra of a polymorph of the 2:1 fumarate salt of β-GPA (Pattern 7C). 
         FIG. 36  is an image depicting a DSC thermogram obtained for a polymorph of the 2:1 fumarate salt of β-GPA (Pattern 7C). 
         FIG. 37  is an image depicting the Raman spectra of a crystalline form of the 2:1 fumarate salt of β-GPA (Pattern 7A). 
         FIG. 38  is an image of crystals of the 2:1 fumarate salt of β-GPA under a polarized microscope (Pattern 7A). 
         FIG. 39  is an image depicting a  1 H NMR spectra of a crystalline form of the 2:1 fumarate salt of β-GPA (Pattern 7A). 
         FIG. 40  is an image depicting a DSC thermogram obtained for a crystalline form of the 2:1 fumarate salt of β-GPA (Pattern 7A). 
         FIG. 41  is an image depicting TGA analysis obtained for a crystalline form of the 2:1 fumarate salt of β-GPA (Pattern 7A). 
         FIGS. 42A-D  are images depicting three-dimensional representations of the unit cell of a crystalline form of the 2:1 fumarate salt of β-GPA based on single crystal analysis (Pattern 7A). 
         FIG. 43  is an image depicting the X-ray powder diffraction (XRPD) pattern obtained for a crystalline form of the 2:1 fumarate salt of β-GPA and the X-ray powder diffraction (XRPD) pattern calculated based on the unit cell identified during single crystal analysis (Pattern 7A). 
         FIG. 44  is an image depicting an overlay of the DSC of β-GPA Pre and Post Jet Milling. 
         FIG. 45  is an image depicting an overlay of the DSC of β-GPA succinate salt Pre and Post Jet Milling. 
         FIG. 46  is an image depicting the PXRD trace of β-GPA Pre and Post Jet Milling. 
         FIG. 47  is an image depicting the PXRD trace of β-GPA succinate salt Pre and Post Jet Milling. 
         FIG. 48  is a graph depicting the tabletability of β-GPA. 
         FIG. 49  is a graph depicting the tabletability of β-GPA succinate salt. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     To identify β-GPA salts with improved properties, the present inventors carried out salt screening experiments with 19 different counterions and eight different solvent systems. Ten of the counterions were prepared in crystalline forms and their properties assessed. Following identification of preferred salts with optimal properties, polymorph screening of these salts was conducted. 
     β-GPA 
     β-GPA has the structure: 
     
       
         
         
             
             
         
       
     
     β-GPA is zwitterionic and highly soluble in water (&gt;50 mg/mL), but has low solubility in organic solvents. β-GPA possesses a basic guanidino group, and is thus capable of forming both 1:1 (β-GPA:acid) and 2:1 (β-GPA:acid) salts with diacids. As used herein, a “2:1 salt” of β-GPA with a diacid, e.g., a 2:1 succinate salt, refers to a salt including two molecules of β-GPA and one molecule of the diacid, e.g., a “2:1 succinate salt” includes two molecules of β-GPA and one molecule of succinic acid. 
     Free β-GPA in solid state is highly crystalline and is generally present as an anhydrate. The crystalline form is non-hygroscopic (e.g., with ˜0.3% water uptake at 80% humidity at 25° C.) with a sharp melting point at 219° C. and an endothermic event at 235° C. by DSC. The crystals of β-GPA have a plate-like crystal morphology. No degradation was observed in experiments at 40° C. at 75% humidity after 4 weeks. 
     The flow properties of β-GPA are sub-optimal. The bulk density is 0.389 g/cc and the tapped density is 0.627 g/cc. These measurements can be used to calculate the Carr&#39;s index and Hausner ratio for a substance. The Carr&#39;s index and Hausner ratio are indicators of flowability of a powder. As known in the art, e.g., as described in Carr R. L. Chem. Eng. 1965, 72, 163-168, the relationship to flowability of a powder to the Carr&#39;s index and Hausner ratio is based on the scale shown in Table 6 below. 
     
       
         
           
               
             
               
                 TABLE 6 
               
             
            
               
                   
               
               
                 Prediction of powder flowability based on Carr&#39;s index and 
               
               
                 Hausner ratio values 
               
            
           
           
               
               
               
            
               
                 Carr&#39;s Index 
                 Flow character 
                 Hausner Ratio 
               
               
                   
               
               
                  1-10 
                 Excellent 
                 1.00-1.11 
               
               
                 11-15 
                 Good 
                 1.12-1.18 
               
               
                 16-20 
                 Fair 
                 1.19-1.25 
               
               
                 21-25 
                 Passable 
                 1.26-1.34 
               
               
                 26-31 
                 Poor 
                 1.35-1.45 
               
               
                 32-37 
                 Very poor 
                 1.46-1.59 
               
               
                 &gt;38 
                 Very very poor 
                 &gt;1.60 
               
               
                   
               
            
           
         
       
     
     The Carr&#39;s index and Hausner ratio for β-GPA are 37.9 (Very poor) and 1.610 (Very very poor) respectively. Experiments utilizing a Hanson Flodex instrument confirmed the poor flowability of β-GPA predicted by the Carr&#39;s index and Hausner ratio. Thus, there exists a need to find a β-GPA salt with improved physical properties. 
     Salts 
     Seventy-six salt screening experiments were carried out with 19 different counterions in different solvent systems including ethanol:water (9:1), isopropyl alcohol, acetone:water (9:1), and acetonitrile. The ten counterions that were prepared in crystalline form were salts prepared with hydrochloric acid, phosphoric acid, methanesulfonic acid, maleic acid, fumaric acid, L-malic acid, succinic acid, and oxalic acid. All of the experiments with basic compounds, e.g., L-aspartic acid, sodium hydroxide, potassium hydroxide, or magnesium hydroxide, resulted in isolation of only β-GPA or the basic compound individually. 
     Of the salts that were prepared, the hydrochloric acid, L-malic acid, phosphoric acid, methanesulfonic acid, and ethanesulfonic acid salts were found to be stable in dry conditions, but deliquesced under high humidity conditions. The maleic acid, fumaric acid, succinic acid, and oxalic acid salts were found to be stable in both dry and humid conditions. The maleic acid, fumaric acid, and oxalic acid salts were found to have 1:1 (β-GPA:acid) stoichiometry, whereas the succinic acid salt was found to have 2:1 (β-GPA:acid) stoichiometry. Further experiments to generate 2:1 salts with fumaric, oxalic, and maleic acid were conducted, resulting in the preparation of 2:1 salts with maleic acid and fumaric acid. 
     Dynamic vapor sorption experiments were conducted on the 1:1 maleate salt, the 1:1 fumarate salt, the 2:1 succinate salt, and the 1:1 oxalate salt. The fumarate, succinate, and oxalate salts were found to exhibit less than 1% moisture uptake during the DVS experiment with no form change observed by XRPD after the experiment. The maleate salt exhibited ˜25% moisture uptake with no form change observed by XRPD after the experiment. Solid form stability studies of the fumarate, succinate, and oxalate salts were carried out at 40° C. and 75% humidity for seven days. All three salts were found to be stable under these conditions. 
     The bulk density and tapped density for the three salts was determined as shown in Table 7 below. 
                     TABLE 7                  Bulk density and tapped density measurements                                 Salt   Bulk density   Tapped density                   oxalate (1:1)   0.505 g/cc   0.623 g/cc           succinate (2:1)   0.405 g/cc   0.472 g/cc           fumarate (2:1)   0.576 g/cc   0.613 g/cc                    
The Carr&#39;s index and Hausner ratios were calculated for each of the three salts, and as shown in Table 8, the three salts exhibit greatly improved predicted flow properties compared to β-GPA. The predicted flow properties were confirmed by experiments utilizing a Hanson Flodex instrument.
 
                     TABLE 8                  Flow properties of three β-GPA salts compared to β-GPA                             Compound   Carr&#39;s index   Hausner ratio   Flow character               β-GPA   37.9   1.610   Very poor       β-GPA oxalate (1:1)   18.7   1.23    Fair       β-GPA succinate (2:1)   14.3   1.167   Good       β-GPA fumarate (2:1)    5.9   1.063   Excellent                    
Polymorph screening of the 2:1 fumarate salt of β-GPA was carried out in 15 different solvent systems at 15° C. and 45° C. and the solubility of the salt was determined gravimetrically. Most of the experiments resulted in no change in polymorph. However, a new polymorph of β-GPA (Pattern 7C) was formed upon lypohilization of the 2:1 salt and fast evaporation, or lyophilization of β-GPA and fumaric acid in 2:1 (β-GPA:acid) stiochiometry. The new polymorph was found to contain some amorphous material, and was unstable.
 
     Crystalline β-GPA, or a pharmaceutically acceptable salt thereof, is defined as a solid comprising β-GPA, or a pharmaceutically acceptable salt thereof, in which the constituent molecules are packed in a regularly ordered repeating pattern extending in all three spatial dimensions. Identification of crystallinity is readily accomplished in a number of ways known to those skilled in the art. Microscopic examination of a test composition will reveal the presence of regular shapes suggesting ordered internal structure, e.g., the 1:1 fumarate salt of β-GPA produced in Example 2 has rod-like morphology. 
     XRPD is another method for identifying crystalline β-GPA, or pharmaceutically acceptable salts thereof. The regularly ordered structure of constituent molecules in crystal diffracts incident X-rays in a distinct pattern depicted as a spectrum of peaks. This pattern of peaks for the 2:1 fumarate salt of β-GPA is shown in  FIG. 43 . While the XRPD peaks for a particular crystal may vary in intensity, the same general pattern will be present in replicate XRPD analysis. 
     Crystalline 2:1 fumarate salt of β-GPA exhibits an XRPD dominant peak at about 27 2θ (°), ordinarily about 26.7. By “about,” as used herein, is meant within the typical variation in measurement of XRPD peaks. Such variations may result from the use of different instruments, instrument settings, batches of product, post-crystallization processing such as micronization or milling, and with varying sample preparation methods. In general, about means±0.5 2θ (°). 
     Illustrative examples of other dominant peaks for crystalline 2:1 fumarate salt of β-GPA are at about 19, 20, 21, 23, and 29 2θ (°), ordinarily 19.2, 19.6, 20.5, 22.8, and 28.6 2θ (°). Representative peaks for crystalline 2:1 fumarate salt of β-GPA are shown in Table 2. 
     The identification of a crystalline form of β-GPA, or a pharmaceutically acceptable salt thereof, need not require the presence of any one or more of the dominant peaks seen in  FIG. 43  or listed in Table 2. The presence or absence of dominant peaks is ordinarily taken into account with other diagnostic characteristics, e.g., DSC thermogram or TGA graph, to identify a candidate as a particular crystalline form of β-GPA, or a pharmaceutically acceptable salt thereof. 
     Crystalline 1:1 fumarate salt of β-GPA is also characterized by DSC thermogram which reveals an endothermic onset at 171° C. in differential scanning calorimetry profile. Typically, some variation in this measurement also will be encountered (e.g., ±1-3° C.). 
     Crystalline 2:1 fumarate salt of β-GPA is also characterized by DSC thermogram which reveals an endothermic onset at 187° C. and 251° C. in differential scanning calorimetry profile. Typically, some variation in this measurement also will be encountered (e.g., ±1-3° C.). 
     Crystalline 1:1 and 2:1 fumarate salt of β-GPA may also be characterized by thermal gravimetric analysis, e.g., by a loss of weight from 31° C. to 140° C. of less than 1%. 
     Treatment Methods 
     β-GPA has recently been found to be effective for the suppression of metastasis. The mechanism of action has been hypothesized as inhibition of creatine transport and/or creatine kinase. The phosphocreatine system promotes metastasis by enhancing the survival of disseminated cancer cells in the liver by acting as an energetic store for ATP generation to endure hepatic hypoxia. Inhibition of creatine transport into cancer cells limits the amount of phosphocreatine available to use in the production of ATP. Inhibition of creatine kinase inhibits the production of ATP through conversion of phosphocreatine to creatine. 
     Typical vascularized tumors that can be treated with the method include solid tumors, particularly carcinomas, which require a vascular component for the provision of oxygen and nutrients. Exemplary solid tumors include, but are not limited to, carcinomas of the lung, breast, bone, ovary, stomach, pancreas, larynx, esophagus, testes, liver, parotid, biliary tract, colon, rectum, cervix, uterus, endometrium, kidney, bladder, prostate, thyroid, squamous cell carcinomas, adenocarcinomas, small cell carcinomas, melanomas, gliomas, glioblastomas, neuroblastomas, Kaposi&#39;s sarcoma, and sarcomas. 
     Treating cancer can result in a reduction in size or volume of a tumor. For example, after treatment, tumor size is reduced by 5% or greater (e.g., 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or greater) relative to its size prior to treatment. Size of a tumor may be measured by any reproducible means of measurement. For example, the size of a tumor may be measured as a diameter of the tumor. 
     Treating cancer may further result in a decrease in number of tumors. For example, after treatment, tumor number is reduced by 5% or greater (e.g., 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or greater) relative to number prior to treatment. Number of tumors may be measured by any reproducible means of measurement, e.g., the number of tumors may be measured by counting tumors visible to the naked eye or at a specified magnification (e.g., 2×, 3×, 4×, 5×, 10×, or 50×). 
     Treating cancer can result in a decrease in number of metastatic nodules in other tissues or organs distant from the primary tumor site. For example, after treatment, the number of metastatic nodules is reduced by 5% or greater (e.g., 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or greater) relative to number prior to treatment. The number of metastatic nodules may be measured by any reproducible means of measurement. For example, the number of metastatic nodules may be measured by counting metastatic nodules visible to the naked eye or at a specified magnification (e.g., 2×, 10×, or 50×). 
     Treating cancer can result in an increase in average survival time of a population of subjects treated according to the present invention in comparison to a population of untreated subjects. For example, the average survival time is increased by more than 30 days (more than 60 days, 90 days, or 120 days). An increase in average survival time of a population may be measured by any reproducible means. An increase in average survival time of a population may be measured, for example, by calculating for a population the average length of survival following initiation of treatment with the compound of the invention. An increase in average survival time of a population may also be measured, for example, by calculating for a population the average length of survival following completion of a first round of treatment with a pharmaceutically acceptable salt of the invention. 
     Treating cancer can also result in a decrease in the mortality rate of a population of treated subjects in comparison to an untreated population. For example, the mortality rate is decreased by more than 2% (e.g., more than 5%, 10%, or 25%). A decrease in the mortality rate of a population of treated subjects may be measured by any reproducible means, for example, by calculating for a population the average number of disease-related deaths per unit time following initiation of treatment with a pharmaceutically acceptable salt of the invention. A decrease in the mortality rate of a population may also be measured, for example, by calculating for a population the average number of disease-related deaths per unit time following completion of a first round of treatment with a pharmaceutically acceptable salt of the invention. 
     Compositions 
     Within the scope of this invention is a composition that contains a suitable excipient and one or more of the pharmaceutically acceptable salts described above. The composition can be a pharmaceutical composition that contains a pharmaceutically acceptable excipient, a dietary composition that contains a dietarily acceptable suitable excipient, or a cosmetic composition that contains a cosmetically acceptable excipient. 
     The term “pharmaceutical composition” refers to the combination of an active agent with a excipient, inert or active, making the composition especially suitable for diagnostic or therapeutic use in vivo or ex vivo. A “pharmaceutically acceptable excipient,” after administered to or upon a subject, does not cause undesirable physiological effects. The excipient in the pharmaceutical composition must be “acceptable” also in the sense that it is compatible with the active ingredient and can be capable of stabilizing it. One or more solubilizing agents can be utilized as pharmaceutical excipients for delivery of an active compound. Examples of a pharmaceutically acceptable excipient include, but are not limited to, biocompatible vehicles, adjuvants, additives, and diluents to achieve a composition usable as a dosage form. Examples of other excipients include colloidal silicon oxide, magnesium stearate, cellulose, sodium lauryl sulfate, and D&amp;C Yellow #10. 
     As used herein, the term “pharmaceutically acceptable salt” refers to those salts which are, within the scope of sound medical judgment, suitable for use in contact with the tissues of humans and lower animals without undue toxicity, irritation, or allergic response, and are commensurate with a reasonable benefit/risk ratio. Pharmaceutically acceptable salts of amines, carboxylic acids, and other types of compounds, are well known in the art. For example, S. M. Berge, et al. describe pharmaceutically acceptable salts in detail in J. Pharmaceutical Sciences, 66:1-19 (1977). The salts can be prepared in situ during the final isolation and purification of the compounds of the invention, or separately by reacting a free base or free acid function with a suitable reagent, as described generally below. For example, a free base function can be reacted with a suitable acid. Furthermore, where the compounds of the invention carry an acidic moiety, suitable pharmaceutically acceptable salts thereof may, include metal salts such as alkali metal salts, e.g. sodium or potassium salts; and alkaline earth metal salts, e.g. calcium or magnesium salts. Examples of pharmaceutically acceptable, nontoxic acid addition salts are salts of an amino group formed with inorganic acids such as hydrochloric acid, hydrobromic acid, phosphoric acid, sulfuric acid and perchloric acid or with organic acids such as acetic acid, oxalic acid, maleic acid, tartaric acid, citric acid, succinic acid, fumaric, or malonic acid or by using other methods used in the art such as ion exchange. Other pharmaceutically acceptable salts, include adipate, alginate, ascorbate, aspartate, benzenesulfonate, benzoate, bisulfate, borate, butyrate, camphorate, camphorsulfonate, citrate, cyclopentanepropionate, digluconate, dodecylsulfate, ethanesulfonate, formate, fumarate, glucoheptonate, glycerophosphate, gluconate, hemisulfate, heptanoate, hexanoate, hydroiodide, 2-hydroxy-ethanesulfonate, lactobionate, lactate, laurate, lauryl sulfate, malate, maleate, malonate, methanesulfonate, 2-naphthalenesulfonate, nicotinate, nitrate, oleate, oxalate, palmitate, pamoate, pectinate, persulfate, 3-phenylpropionate, phosphate, picrate, pivalate, propionate, stearate, succinate, sulfate, tartrate, thiocyanate, p-toluenesulfonate, undecanoate, and valerate salts. Representative alkali or alkaline earth metal salts include sodium, lithium, potassium, calcium, and magnesium. Further pharmaceutically acceptable salts include, when appropriate, nontoxic ammonium, quaternary ammonium, and amine cations formed using counterions such as halide, hydroxide, carboxylate, sulfate, phosphate, nitrate, loweralkyl sulfonate and aryl sulfonate. 
     As described above, the pharmaceutical compositions of the present invention additionally include a pharmaceutically acceptable excipient, which, as used herein, includes any and all solvents, diluents, or other liquid vehicle, dispersion or suspension aids, surface active agents, isotonic agents, thickening or emulsifying agents, preservatives, solid binders, and lubricants, as suited to the particular dosage form desired. Remington&#39;s Pharmaceutical Sciences, Sixteenth Edition, E. W. Martin (Mack Publishing Co., Easton, Pa., 1980) discloses various excipients used in formulating pharmaceutical compositions and known techniques for the preparation thereof. Except insofar as any conventional excipient medium is incompatible with the compounds of the invention, such as by producing any undesirable biological effect or otherwise interacting in a deleterious manner with any other component(s) of the pharmaceutical composition, its use is contemplated to be within the scope of this invention. Some examples of materials which can serve as pharmaceutically acceptable excipients include, but are not limited to, sugars such as lactose, glucose and sucrose; starches such as corn starch and potato starch; cellulose and its derivatives such as sodium carboxymethyl cellulose, ethyl cellulose and cellulose acetate; powdered tragacanth; malt; gelatine; talc; excipients such as cocoa butter and suppository waxes; oils such as peanut oil, cottonseed oil; safflower oil, sesame oil; olive oil; corn oil and soybean oil; glycols; such as propylene glycol; esters such as ethyl oleate and ethyl laurate; agar; natural and synthetic phospholipids, such as soybean and egg yolk phosphatides, lecithin, hydrogenated soy lecithin, dimyristoyl lecithin, dipalmitoyl lecithin, distearoyl lecithin, dioleoyl lecithin, hydroxylated lecithin, lysophosphatidylcholine, cardiolipin, sphingomyelin, phosphatidylcholine, phosphatidyl ethanolamine, diastearoyl phosphatidylethanolamine (DSPE) and its pegylated esters, such as DSPE-PEG750 and, DSPE-PEG2000, phosphatidic acid, phosphatidyl glycerol and phosphatidyl serine. Commercial grades of lecithin which are preferred include those which are available under the trade name Phosal® or Phospholipon® and include Phosal 53 MCT, Phosal 50 PG, Phosal 75 SA, Phospholipon 90H, Phospholipon 90G and Phospholipon 90 NG; soy-phosphatidylcholine (SoyPC) and DSPE-PEG2000 are particularly preferred; buffering agents such as magnesium hydroxide and aluminum hydroxide; alginic acid; pyrogen-free water; isotonic saline; Ringer&#39;s solution; ethyl alcohol, and phosphate buffer solutions, as well as other non-toxic compatible lubricants such as sodium lauryl sulfate and magnesium stearate, as well as coloring agents, releasing agents, coating agents, sweetening, flavoring and perfuming agents, preservatives and antioxidants can also be present in the composition, according to the judgment of the formulator. 
     The above-described composition, in any of the forms described above, can be used for treating cancer, or any other disease or condition described herein. An effective amount refers to the amount of an active compound/agent that is required to confer a therapeutic effect on a treated subject. Effective doses will vary, as recognized by those skilled in the art, depending on the types of diseases treated, route of administration, excipient usage, and the possibility of co-usage with other therapeutic treatment. A pharmaceutical composition of this invention can be administered parenterally, orally, nasally, rectally, topically, or buccally. The term “parenteral” as used herein refers to subcutaneous, intracutaneous, intravenous, intramuscular, intraarticular, intraarterial, intrasynovial, intrasternal, intrathecal, intralesional, or intracranial injection, as well as any suitable infusion technique. 
     A sterile injectable composition can be a solution or suspension in a non-toxic parenterally acceptable diluent or solvent. Such solutions include, but are not limited to, 1,3-butanediol, mannitol, water, Ringer&#39;s solution, and isotonic sodium chloride solution. In addition, fixed oils are conventionally employed as a solvent or suspending medium (e.g., synthetic mono- or diglycerides). Fatty acids, such as, but not limited to, oleic acid and its glyceride derivatives, are useful in the preparation of injectables, as are natural pharmaceutically acceptable oils, such as, but not limited to, olive oil or castor oil, orpolyoxyethylated versions thereof. These oil solutions or suspensions also can contain a long chain alcohol diluent or dispersant such as, but not limited to, carboxymethyl cellulose, or similar dispersing agents. Other commonly used surfactants, such as, but not limited to, Tweens or Spans or other similar emulsifying agents or bioavailability enhancers, which are commonly used in the manufacture of pharmaceutically acceptable solid, liquid, or other dosage forms also can be used for the purpose of formulation. 
     A composition for oral administration can be any orally acceptable dosage form including capsules, tablets, emulsions and aqueous suspensions, dispersions, and solutions. In the case of tablets, commonly used excipients include, but are not limited to, lactose and corn starch. Lubricating agents, such as, but not limited to, magnesium stearate, also are typically added. For oral administration in a capsule form, useful diluents include, but are not limited to, lactose and dried corn starch. When aqueous suspensions or emulsions are administered orally, the active ingredient can be suspended or dissolved in an oily phase combined with emulsifying or suspending agents. If desired, certain sweetening, flavoring, or coloring agents can be added. In some embodiments, the pharmaceutically acceptable salts of the invention may be formulated as microparticulates such as by extrusion spheronization. In some embodiments, the pharmaceutically acceptable salts of the invention are formulated in an immediate release formulation. In some embodiments, the pharmaceutically acceptable salts of the invention are formulated in a sustained release formulation. 
     Pharmaceutical compositions for topical administration according to the described invention can be formulated as solutions, ointments, creams, suspensions, lotions, powders, pastes, gels, sprays, aerosols, or oils. Alternatively, topical formulations can be in the form of patches or dressings impregnated with active ingredient(s), which can optionally include one or more excipients or diluents. In some preferred embodiments, the topical formulations include a material that would enhance absorption or penetration of the active agent(s) through the skin or other affected areas. 
     A topical composition contains a safe and effective amount of a dermatologically acceptable excipient suitable for application to the skin. A “cosmetically acceptable” or “dermatologically-acceptable” composition or component refers a composition or component that is suitable for use in contact with human skin without undue toxicity, incompatibility, instability, or allergic response. The excipient enables an active agent and optional component to be delivered to the skin at an appropriate concentration(s). The excipient thus can act as a diluent, dispersant, solvent, or the like to ensure that the active materials are applied to and distributed evenly over the selected target at an appropriate concentration. The excipient can be solid, semi-solid, or liquid. The excipient can be in the form of a lotion, a cream, or a gel, in particular one that has a sufficient thickness or yield point to prevent the active materials from sedimenting. The excipient can be inert or possess dermatological benefits. It also should be physically and chemically compatible with the active components described herein, and should not unduly impair stability, efficacy, or other use benefits associated with the composition. 
     Combination Therapies 
     In some embodiments, the pharmaceutical composition may further include an additional compound having antiproliferative activity. The additional compound having antiproliferative activity can be selected from a group of antiproliferative agents including those shown in Table 9. 
     It will also be appreciated that the compounds and pharmaceutical compositions of the present invention can be formulated and employed in combination therapies, that is, the compounds and pharmaceutical compositions can be formulated with or administered concurrently with, prior to, or subsequent to, one or more other desired therapeutics or medical procedures. The particular combination of therapies (therapeutics or procedures) to employ in a combination regimen will take into account compatibility of the desired therapeutics and/or procedures and the desired therapeutic effect to be achieved. It will also be appreciated that the therapies employed may achieve a desired effect for the same disorder, or they may achieve different effects (e.g., control of any adverse effects). 
     By “antiproliferative agent” is meant any antiproliferative agent, including those antiproliferative agents listed in Table 9, any of which can be used in combination with a pharmaceutically acceptable salt of the invention to treat the medical conditions recited herein. Antiproliferative agents also include organo-platine derivatives, naphtoquinone and benzoquinone derivatives, chrysophanic acid and anthroquinone derivatives thereof. 
     
       
         
           
               
               
             
               
                 TABLE 9 
               
               
                   
               
             
            
               
                 Alkylating agents 
                 Busulfan 
               
               
                   
                 dacarbazine 
               
               
                   
                 ifosfamide 
               
               
                   
                 hexamethylmelamine 
               
               
                   
                 thiotepa 
               
               
                   
                 dacarbazine 
               
               
                   
                 lomustine 
               
               
                   
                 cyclophosphamide 
               
               
                   
                 Chlorambucil 
               
               
                   
                 procarbazine 
               
               
                   
                 altretamine 
               
               
                   
                 estramustine phosphate 
               
               
                   
                 mechlorethamine 
               
               
                   
                 streptozocin 
               
               
                   
                 temozolomide 
               
               
                   
                 Semustine 
               
               
                 Platinum agents 
                 spiroplatin 
               
               
                   
                 tetraplatin 
               
               
                   
                 ormaplatin 
               
               
                   
                 iproplatin 
               
               
                   
                 ZD-0473 (AnorMED) 
               
               
                   
                 oxaliplatin 
               
               
                   
                 carboplatin 
               
               
                   
                 lobaplatin (Aeterna) 
               
               
                   
                 satraplatin (Johnson Matthey) 
               
               
                   
                 BBR-3464 (Hoffmann-La Roche) 
               
               
                   
                 SM-11355 (Sumitomo) 
               
               
                   
                 AP-5280 (Access) 
               
               
                   
                 cisplatin 
               
               
                 Antimetabolites 
                 azacytidine 
               
               
                   
                 Floxuridine 
               
               
                   
                 2-chlorodeoxyadenosine 
               
               
                   
                 6-mercaptopurine 
               
               
                   
                 6-thioguanine 
               
               
                   
                 cytarabine 
               
               
                   
                 2-fluorodeoxy cytidine 
               
               
                   
                 methotrexate 
               
               
                   
                 tomudex 
               
               
                   
                 fludarabine 
               
               
                   
                 raltitrexed 
               
               
                   
                 trimetrexate 
               
               
                   
                 deoxycoformycin 
               
               
                   
                 pentostatin 
               
               
                   
                 hydroxyurea 
               
               
                   
                 decitabine (SuperGen) 
               
               
                   
                 clofarabine (Bioenvision) 
               
               
                   
                 irofulven (MGI Pharma) 
               
               
                   
                 DMDC (Hoffmann-La Roche) 
               
               
                   
                 ethynylcytidine (Taiho) 
               
               
                   
                 gemcitabine 
               
               
                   
                 capecitabine 
               
               
                 Topoisomerase 
                 amsacrine 
               
               
                 inhibitors 
                 epirubicin 
               
               
                   
                 etoposide 
               
               
                   
                 teniposide or mitoxantrone 
               
               
                   
                 7-ethyl-10-hydroxy-camptothecin 
               
               
                   
                 dexrazoxanet (TopoTarget) 
               
               
                   
                 pixantrone (Novuspharma) 
               
               
                   
                 rebeccamycin analogue (Exelixis) 
               
               
                   
                 BBR-3576 (Novuspharma) 
               
               
                   
                 rubitecan (SuperGen) 
               
               
                   
                 irinotecan (CPT-11) 
               
               
                   
                 topotecan 
               
               
                   
                 exatecan mesylate (Daiichi) 
               
               
                   
                 quinamed (ChemGenex) 
               
               
                   
                 gimatecan (Sigma-Tau) 
               
               
                   
                 diflomotecan (Beaufour-Ipsen) 
               
               
                   
                 TAS-103 (Taiho) 
               
               
                   
                 elsamitrucin (Spectrum) 
               
               
                   
                 J-107088 (Merck &amp; Co) 
               
               
                   
                 BNP-1350 (BioNumerik) 
               
               
                   
                 CKD-602 (Chong Kun Dang) 
               
               
                   
                 KW-2170 (Kyowa Hakko) 
               
               
                   
                 hydroxycamptothecin (SN-38) 
               
               
                 Antitumor 
                 valrubicin 
               
               
                 antibiotics 
                 therarubicin 
               
               
                   
                 idarubicin 
               
               
                   
                 rubidazone 
               
               
                   
                 plicamycin 
               
               
                   
                 porfiromycin 
               
               
                   
                 mitoxantrone (novantrone) 
               
               
                   
                 amonafide 
               
               
                   
                 azonafide 
               
               
                   
                 anthrapyrazole 
               
               
                   
                 oxantrazole 
               
               
                   
                 losoxantrone 
               
               
                   
                 MEN-10755 (Menarini) 
               
               
                   
                 GPX-100 (Gem Pharmaceuticals) 
               
               
                   
                 Epirubicin 
               
               
                   
                 mitoxantrone 
               
               
                   
                 doxorubicin 
               
               
                 Antimitotic 
                 colchicine 
               
               
                 agents 
                 vinblastine 
               
               
                   
                 vindesine 
               
               
                   
                 dolastatin 10 (NCI) 
               
               
                   
                 rhizoxin (Fujisawa) 
               
               
                   
                 mivobulin (Warner-Lambert) 
               
               
                   
                 cemadotin (BASF) 
               
               
                   
                 RPR 109881A (Aventis) 
               
               
                   
                 TXD 258 (Aventis) 
               
               
                   
                 epothilone B (Novartis) 
               
               
                   
                 T 900607 (Tularik) 
               
               
                   
                 T 138067 (Tularik) 
               
               
                   
                 cryptophycin 52 (Eli Lilly) 
               
               
                   
                 vinflunine (Fabre) 
               
               
                   
                 auristatin PE (Teikoku Hormone) 
               
               
                   
                 BMS 247550 (BMS) 
               
               
                   
                 BMS 184476 (BMS) 
               
               
                   
                 BMS 188797 (BMS) 
               
               
                   
                 taxoprexin (Protarga) 
               
               
                   
                 SB 408075 (GlaxoSmithKline) 
               
               
                   
                 Vinorelbine 
               
               
                   
                 Trichostatin A 
               
               
                   
                 E7010 (Abbott) 
               
               
                   
                 PG-TXL (Cell Therapeutics) 
               
               
                   
                 IDN 5109 (Bayer) 
               
               
                   
                 A 105972 (Abbott) 
               
               
                   
                 A 204197 (Abbott) 
               
               
                   
                 LU 223651 (BASF) 
               
               
                   
                 D 24851 (ASTAMedica) 
               
               
                   
                 ER-86526 (Eisai) 
               
               
                   
                 combretastatin A4 (BMS) 
               
               
                   
                 isohomohalichondrin-B (PharmaMar) 
               
               
                   
                 ZD 6126 (AstraZeneca) 
               
               
                   
                 AZ10992 (Asahi) 
               
               
                   
                 IDN-5109 (Indena) 
               
               
                   
                 AVLB (Prescient NeuroPharma) 
               
               
                   
                 azaepothilone B (BMS) 
               
               
                   
                 BNP-7787 (BioNumerik) 
               
               
                   
                 CA-4 prodrug (OXiGENE) 
               
               
                   
                 dolastatin-10 (NIH) 
               
               
                   
                 CA-4 (OXiGENE) 
               
               
                   
                 docetaxel 
               
               
                   
                 vincristine 
               
               
                   
                 paclitaxel 
               
               
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                 inhibitors 
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                 letrozole 
               
               
                   
                 anastrazole 
               
               
                   
                 YM-511 (Yamanouchi) 
               
               
                   
                 formestane 
               
               
                   
                 exemestane 
               
               
                 Thymidylate 
                 pemetrexed (Eli Lilly) 
               
               
                 synthase 
                 ZD-9331 (BTG) 
               
               
                 inhibitors 
                 nolatrexed (Eximias) 
               
               
                   
                 CoFactor ™ (BioKeys) 
               
               
                 DNA antagonists 
                 trabectedin (PharmaMar) 
               
               
                   
                 glufosfamide (Baxter International) 
               
               
                   
                 albumin + 32P (Isotope Solutions) 
               
               
                   
                 thymectacin (NewBiotics) 
               
               
                   
                 edotreotide (Novartis) 
               
               
                   
                 mafosfamide (Baxter International) 
               
               
                   
                 apaziquone (Spectrum Pharmaceuticals) 
               
               
                   
                 O6 benzyl guanine (Paligent) 
               
               
                 Farnesyltransferase 
                 arglabin (NuOncology Labs) 
               
               
                 inhibitors 
                 lonafarnib (Schering-Plough) 
               
               
                   
                 BAY-43-9006 (Bayer) 
               
               
                   
                 tipifarnib (Johnson &amp; Johnson) 
               
               
                   
                 perillyl alcohol (DOR BioPharma) 
               
               
                 Pump inhibitors 
                 CBT-1 (CBA Pharma) 
               
               
                   
                 tariquidar (Xenova) 
               
               
                   
                 MS-209 (Schering AG) 
               
               
                   
                 zosuquidar trihydrochloride (Eli Lilly) 
               
               
                   
                 biricodar dicitrate (Vertex) 
               
               
                 Histone 
                 tacedinaline (Pfizer) 
               
               
                 acetyltransferase 
                 SAHA (Aton Pharma) 
               
               
                 inhibitors 
                 MS-275 (Schering AG) 
               
               
                   
                 pivaloyloxymethyl butyrate (Titan) 
               
               
                   
                 depsipeptide (Fujisawa) 
               
               
                 Metalloproteinase 
                 Neovastat (Aeterna Laboratories) 
               
               
                 inhibitors 
                 marimastat (British Biotech) 
               
               
                   
                 CMT-3 (CollaGenex) 
               
               
                   
                 BMS-275291 (Celltech) 
               
               
                 Ribonucleoside 
                 gallium maltolate (Titan) 
               
               
                 reductase 
                 triapine (Vion) 
               
               
                 inhibitors 
                 tezacitabine (Aventis) 
               
               
                   
                 didox (Molecules for Health) 
               
               
                 TNF alpha 
                 virulizin (Lorus Therapeutics) 
               
               
                 agonists/ 
                 CDC-394 (Celgene) 
               
               
                 antagonists 
                 revimid (Celgene) 
               
               
                 Endothelin A 
                 atrasentan (Abbott) 
               
               
                 receptor  
                 ZD-4054 (AstraZeneca) 
               
               
                 antagonist 
                 YM-598 (Yamanouchi) 
               
               
                 Retinoic acid 
                 fenretinide (Johnson &amp; Johnson) 
               
               
                 receptor agonists 
                 LGD-1550 (Ligand) 
               
               
                   
                 alitretinoin (Ligand) 
               
               
                 Immuno- 
                 interferon 
               
               
                 modulators 
                 oncophage (Antigenics) 
               
               
                   
                 GMK (Progenics) 
               
               
                   
                 adenocarcinoma vaccine (Biomira) 
               
               
                   
                 CTP-37 (AVI BioPharma) 
               
               
                   
                 IRX-2 (Immuno-Rx) 
               
               
                   
                 PEP-005 (Peplin Biotech) 
               
               
                   
                 synchrovax vaccines (CTL Immuno) 
               
               
                   
                 melanoma vaccine (CTL Immuno) 
               
               
                   
                 p21 RAS vaccine (GemVax) 
               
               
                   
                 MAGE-A3 (GSK) 
               
               
                   
                 nivolumab (BMS) 
               
               
                   
                 abatacept (BMS) 
               
               
                   
                 pembrolizumab 
               
               
                   
                 avelumab 
               
               
                   
                 CTL019 
               
               
                   
                 MIW815 
               
               
                   
                 MCS-110 
               
               
                   
                 Anti-IL6 
               
               
                   
                 Anti-LAG3 
               
               
                   
                 Anti-PD1 
               
               
                   
                 Anti-TIM3 
               
               
                   
                 Anti-VISTA 
               
               
                   
                 TLR7/8 dual agonist 
               
               
                   
                 TReg inhibitors 
               
               
                   
                 Anti-OX40 
               
               
                   
                 Anti-SLAMF7 
               
               
                   
                 Anti-CD40 
               
               
                   
                 Anti-CD47 
               
               
                   
                 Anti-CSF-1R 
               
               
                   
                 Anti-KIR 
               
               
                   
                 Anti-NKG2A 
               
               
                   
                 STING agonists 
               
               
                   
                 dexosome therapy (Anosys) 
               
               
                   
                 pentrix (Australian Cancer Technology) 
               
               
                   
                 ISF-154 (Tragen) 
               
               
                   
                 cancer vaccine (Intercell) 
               
               
                   
                 norelin (Biostar) 
               
               
                   
                 BLP-25 (Biomira) 
               
               
                   
                 MGV (Progenics) 
               
               
                   
                 β-alethine (Dovetail) 
               
               
                   
                 CLL therapy (Vasogen) 
               
               
                   
                 Ipilimumab (BMS), 
               
               
                   
                 CM-10 (cCam Biotherapeutics) 
               
               
                   
                 MPDL3280A (Genentech) 
               
               
                   
                 MEDI4736 
               
               
                   
                 PDR001 
               
               
                   
                 LAG525 
               
               
                   
                 CAR-T therapies 
               
               
                   
                 Anti-CD73 
               
               
                   
                 Anti-CTLA4 
               
               
                   
                 Anti-IL10 
               
               
                   
                 Anti-PDL1 
               
               
                   
                 Anti-TIGIT 
               
               
                   
                 STAT3 inhibitors 
               
               
                   
                 TGF beta inhibitors 
               
               
                   
                 Anti-CD137 (4-1BB) 
               
               
                   
                 Anti-GITR 
               
               
                   
                 A2aR antagonist 
               
               
                   
                 Anti-CCR2 
               
               
                   
                 Anti-CCR4 
               
               
                   
                 Anti-CXCR2 
               
               
                   
                 Anti-CXCR4 
               
               
                   
                 IDO/TDO inhibitors 
               
               
                 Hormonal and 
                 estrogens 
               
               
                 antihormonal 
                 conjugated estrogens 
               
               
                 agents 
                 ethinyl estradiol 
               
               
                   
                 chlortrianisen 
               
               
                   
                 idenestrol 
               
               
                   
                 hydroxyprogesterone caproate 
               
               
                   
                 medroxyprogesterone 
               
               
                   
                 testosterone 
               
               
                   
                 testosterone propionate; 
               
               
                   
                 fluoxymesterone 
               
               
                   
                 methyltestosterone 
               
               
                   
                 diethylstilbestrol 
               
               
                   
                 megestrol 
               
               
                   
                 bicalutamide 
               
               
                   
                 flutamide 
               
               
                   
                 nilutamide 
               
               
                   
                 dexamethasone 
               
               
                   
                 prednisone 
               
               
                   
                 methylprednisolone 
               
               
                   
                 prednisolone 
               
               
                   
                 aminoglutethimide 
               
               
                   
                 leuprolide 
               
               
                   
                 octreotide 
               
               
                   
                 mitotane 
               
               
                   
                 P-04 (Novogen) 
               
               
                   
                 2-methoxyestradiol (EntreMed) 
               
               
                   
                 arzoxifene (Eli Lilly) 
               
               
                   
                 tamoxifen 
               
               
                   
                 toremofine 
               
               
                   
                 goserelin 
               
               
                   
                 Leuporelin 
               
               
                   
                 bicalutamide 
               
               
                 Photodynamic 
                 talaporfin (Light Sciences) 
               
               
                 agents 
                 Theralux (Theratechnologies) 
               
               
                   
                 motexafin gadolinium (Pharmacyclics) 
               
               
                   
                 Pd-bacteriopheophorbide (Yeda) 
               
               
                   
                 lutetium texaphyrin (Pharmacyclics) 
               
               
                   
                 hypericin 
               
               
                 Kinase Inhibitors 
                 imatinib (Novartis) 
               
               
                   
                 leflunomide (Sugen/Pharmacia) 
               
               
                   
                 ZD1839 (AstraZeneca) 
               
               
                   
                 erlotinib (Oncogene Science) 
               
               
                   
                 canertinib (Pfizer) 
               
               
                   
                 squalamine (Genaera) 
               
               
                   
                 SU5416 (Pharmacia) 
               
               
                   
                 SU6668 (Pharmacia) 
               
               
                   
                 ZD4190 (AstraZeneca) 
               
               
                   
                 ZD6474 (AstraZeneca) 
               
               
                   
                 vatalanib (Novartis) 
               
               
                   
                 PKI166 (Novartis) 
               
               
                   
                 GW2016 (GlaxoSmithKline) 
               
               
                   
                 EKB-509 (Wyeth) 
               
               
                   
                 trastuzumab (Genentech) 
               
               
                   
                 OSI-774 (Tarceva ™) 
               
               
                   
                 CI-1033 (Pfizer) 
               
               
                   
                 SU11248 (Pharmacia) 
               
               
                   
                 RH3 (York Medical) 
               
               
                   
                 Genistein 
               
               
                   
                 Radicinol 
               
               
                   
                 Met-MAb (Roche) 
               
               
                   
                 SR-27897 (CCK A inhibitor, Sanofi-Synthelabo) 
               
               
                   
                 tocladesine (cyclic AMP agonist, Ribapharm) 
               
               
                   
                 alvocidib (CDK inhibitor, Aventis) 
               
               
                   
                 CV-247 (COX-2 inhibitor, Ivy Medical) 
               
               
                   
                 P54 (COX-2 inhibitor, Phytopharm) 
               
               
                   
                 CapCell ™ (CYP450 stimulant, Bavarian Nordic) 
               
               
                   
                 GCS-100 (gal3 antagonist, GlycoGenesys) 
               
               
                   
                 G17DT immunogen (gastrin inhibitor, Aphton) 
               
               
                   
                 efaproxiral (oxygenator, Allos Therapeutics) 
               
               
                   
                 PI-88 (heparanase inhibitor, Progen) 
               
               
                   
                 tesmilifene (histamine antagonist, YM BioSciences) 
               
               
                   
                 histamine (histamine H2 receptor agonist, Maxim) 
               
               
                   
                 tiazofurin (IMPDH inhibitor, Ribapharm) 
               
               
                   
                 cilengitide (integrin antagonist, Merck KGaA) 
               
               
                   
                 SR-31747 (IL-1 antagonist, Sanofi-Synthelabo) 
               
               
                   
                 CCI-779 (mTOR kinase inhibitor, Wyeth) 
               
               
                   
                 exisulind (PDE V inhibitor, Cell Pathways) 
               
               
                   
                 dabrafenib 
               
               
                   
                 midostaurin (PKC inhibitor, Novartis) 
               
               
                   
                 bryostatin-1 (PKC stimulant, GPC Biotech) 
               
               
                   
                 CDA-II (apoptosis promotor, Everlife) 
               
               
                   
                 SDX-101 (apoptosis promotor, Salmedix) 
               
               
                   
                 rituximab (CD20 antibody, Genentech 
               
               
                   
                 carmustine 
               
               
                   
                 Mitoxantrone 
               
               
                   
                 Bleomycin 
               
               
                   
                 CP-461 (PDE V inhibitor, Cell Pathways) 
               
               
                   
                 AG-2037 (GART inhibitor, Pfizer) 
               
               
                   
                 WX-UK1 (plasminogen activator inhibitor, Wilex) 
               
               
                   
                 PBI-1402 (PMN stimulant, ProMetic LifeSciences) 
               
               
                   
                 bortezomib (proteasome inhibitor, Millennium) 
               
               
                   
                 SRL-172 (T cell stimulant, SR Pharma) 
               
               
                   
                 TLK-286 (glutathione S transferase inhibitor, Telik) 
               
               
                   
                 PT-100 (growth factor agonist, Point Therapeutics) 
               
               
                   
                 Chrysophanic acid 
               
               
                   
                 Cesium oxides 
               
               
                   
                 BRAF inhibitors, 
               
               
                   
                 PDL1 inhibitors 
               
               
                   
                 MEK inhibitors 
               
               
                   
                 bevacizumab 
               
               
                   
                 angiogenesis inhibitors 
               
               
                   
                 Absinthin 
               
               
                   
                 EKB-569 (Wyeth) 
               
               
                   
                 kahalide F (PharmaMar) 
               
               
                   
                 CEP-701 (Cephalon) 
               
               
                   
                 CEP-751 (Cephalon) 
               
               
                   
                 MLN518 (Millenium) 
               
               
                   
                 PKC412 (Novartis) 
               
               
                   
                 Phenoxodiol (Novogen) 
               
               
                   
                 C225 (ImClone) 
               
               
                   
                 rhu-Mab (Genentech) 
               
               
                   
                 MDX-H210 (Medarex) 
               
               
                   
                 2C4 (Genentech) 
               
               
                   
                 MDX-447 (Medarex) 
               
               
                   
                 ABX-EGF (Abgenix) 
               
               
                   
                 IMC-1C11 (ImClone) 
               
               
                   
                 Tyrphostins 
               
               
                   
                 Gefitinib (Iressa) 
               
               
                   
                 PTK787 (Novartis) 
               
               
                   
                 EMD 72000 (Merck) 
               
               
                   
                 Emodin 
               
               
                   
                 Radicinol 
               
               
                   
                 Vemurafenib (B-Raf enzyme inhibitor,  
               
               
                   
                 Daiichi Sankyo) 
               
               
                   
                 ceflatonin (apoptosis promotor, ChemGenex) 
               
               
                   
                 BCX-1777 (PNP inhibitor, BioCryst) 
               
               
                   
                 ranpirnase (ribonuclease stimulant, Alfacell) 
               
               
                   
                 galarubicin (RNA synthesis inhibitor, Dong-A) 
               
               
                   
                 tirapazamine (reducing agent, SRI International) 
               
               
                   
                 N-acetylcysteine (reducing agent, Zambon) 
               
               
                   
                 R-flurbiprofen (NF-kappaB inhibitor, Encore) 
               
               
                   
                 3CPA (NF-kappaB inhibitor, Active Biotech) 
               
               
                   
                 seocalcitol (vitamin D receptor agonist, Leo) 
               
               
                   
                 131-I-TM-601 (DNA antagonist, TransMolecular) 
               
               
                   
                 eflornithine (ODC inhibitor, ILEX Oncology) 
               
               
                   
                 minodronic acid (osteoclast inhibitor, Yamanouchi) 
               
               
                   
                 indisulam (p53 stimulant, Eisai) 
               
               
                   
                 aplidine (PPT inhibitor, PharmaMar) 
               
               
                   
                 CRS-207 
               
               
                   
                 CHS-828 (cytotoxic agent, Leo) 
               
               
                   
                 trans-retinoic acid (differentiator, NIH) 
               
               
                   
                 MX6 (apoptosis promotor, MAXIA) 
               
               
                   
                 apomine (apoptosis promotor, ILEX Oncology) 
               
               
                   
                 sorafenib 
               
               
                   
                 BRAF inhibitors 
               
               
                   
                 urocidin (apoptosis promotor, Bioniche) 
               
               
                   
                 Ro-31-7453 (apoptosis promotor, La Roche) 
               
               
                   
                 gemtuzumab (CD33 antibody, Wyeth Ayerst) 
               
               
                   
                 PG2 (hematopoiesis enhancer, Pharmagenesis) 
               
               
                   
                 Immunol ™ (triclosan oral rinse, Endo) 
               
               
                   
                 triacetyluridine (uridine prodrug , Wellstat) 
               
               
                   
                 SN-4071 (sarcoma agent, Signature BioScience) 
               
               
                   
                 TransMID-107 ™ (immunotoxin, KS Biomedix) 
               
               
                   
                 PCK-3145 (apoptosis promotor, Procyon) 
               
               
                   
                 doranidazole (apoptosis promotor, Pola) 
               
               
                   
                 cafestol 
               
               
                   
                 kahweol 
               
               
                   
                 caffeic acid 
               
               
                   
                 Tyrphostin AG 
               
               
                   
                 PD-1 inhibitors 
               
               
                   
                 CTLA-4 inhibitors 
               
               
                   
                 brostallicin (apoptosis promotor, Pharmacia) 
               
               
                   
                 β-lapachone 
               
               
                   
                 gelonin 
               
               
                   
               
            
           
         
       
     
     EXAMPLES 
     General Methods 
     Differential Scanning Calorimetry 
     Differential Scanning calorimetry (DCS) data were collected using a TA Instruments Q10 DSC. Typically, samples (2-8 mg) were placed in unsealed, but covered hermetic alodined aluminum sample pans and scanned from 30 to 300° C. at a rate of 10° C./min using a nitrogen purge of 50 mL/min. 
     Thermal Gravimetric Analysis 
     Thermal Gravimetric Analysis (TGA) data were collected using a TA Instruments TGA Q500. Typically, samples (˜10 mg) were placed in an open, pre-tared aluminum sample pan and scanned from 25 to 300° C. at a rate of 10° C./min using a nitrogen purge at 60 mL/min. 
     X-Ray Powder Diffractometer 
     X-ray powder diffraction patterns were obtained using a Bruker D8 Advance equipped with a Cu Kα radiation source (A=1.54° Å), a 9-position sample holder and a LYNXEYE super speed detector. 
     Samples were placed on zero-background, silicon plate holders. 
     Dynamic Vapor Sorption 
     Samples were analyzed using an Aquadyne DVS-2 gravimetric water sorption analyzer. The relative humidity was adjusted between 2-95% and the weight of the sample was continuously monitored and recorded. 
     Proton-Nuclear Magnetic Resonance 
     Sample was prepared by dissolving the compound in deuterated dimethylsulfoxide with 0.05% (v/v) tetramethylsilane (TMS). Spectra were collected at ambient temperature on a Bruker Avance 300 MHz NMR with TopSpin software. The number of scans was 16 for proton NMR. 
     Karl Fischer 
     The apparent water content in samples was determined by Karl Fischer titration using a Mettler Toledo DL39 Coulometric KF Titrator. HYDRANAL-Coulomat AD was used as the titrant. About 20 mg of the solid was used for titration. The analytical parameters are presented in Table 10. 
     
       
         
           
               
             
               
                 TABLE 10 
               
             
            
               
                   
               
               
                 Karl Fischer parameters 
               
            
           
           
               
               
               
            
               
                   
                 KF Parameter 
                 Value 
               
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Speed [%] 
                 40 
               
               
                   
                 Mix time [sec] 
                 10 
               
               
                   
                 Auto start 
                 No 
               
               
                   
                 Blank [μg] 
                 0 
               
               
                   
                 Drift [μg/min]  
                 5 
               
               
                   
                 Calculation 
                 Ug 
               
               
                   
                 Standby 
                 Yes 
               
               
                   
                 Initial drift 
                 &lt;10 
               
               
                   
                 [μg/min] 
                   
               
               
                   
                 Initial Potential 
                 100 
               
               
                   
                 [mV] 
               
               
                   
               
            
           
         
       
     
     Optical Microscopy 
     Samples were analyzed using an Olympus BX53 polarized light microscope equipped with a PAXcam 3 digital microscope camera. 
     Example 1. Profiling of Solid-State β-GPA 
     Solid-state β-GPA was analyzed by XRPD ( FIG. 2 ) and was also observed under a polarized microscope ( FIG. 3 ). The material was found to be crystalline 
     A DSC thermogram of β-GPA is illustrated in  FIG. 4 . The melting onset of β-GPA was found to be around 219° C. followed by an endothermic event at around 237° C. and immediate possible degradation. However, another tiny endothermic event at 187° C. was also exhibited by the material (possible traces of another form of β-GPA). 
     TGA analysis reveals that there is less than 0.1% weight loss in the sample from 30 to 145° C. as illustrated in  FIG. 5 . 
     The  1 H NMR of β-GPA is shown in  FIG. 6 . 
     The DVS experiment of β-GPA revealed around 0.1% moisture absorbed and desorbed when exposed to relative humidity between 0-95 percent ( FIG. 7 ). No change in the solid form was observed after the DVS experiment as confirmed by XRPD. 
     Example 2. Salt Screening 
     Stage I 
     Table 11 illustrates the selected counter ions for the salt screening of β-GPA. Salt screening experiments were designed in 1:1.1 equivalence (eq) for β-GPA to counter ion. 
                     TABLE 11                  List of selected counterions                                     β-       Counterion   Counterion           GPA       sequence   molecular        Sample ID   (mg)   Counterion   #   wt                                         2162-42-1 to 4   30   Hydrochloric   1   36.46               acid                       (36-38%)*               2162-42-5 to 8   30   Hydrobromic   2   80.91               acid                       (48%)*               2162-42-9 to 12   30   Sulfuric acid   3   98.08               (95-98%)*               2162-42-13 to 16   30   Phosphoric acid   4   98.00               (85%)*               2162-42-17 to 20   30   Methane sulfonic   5   96.11               acid (98%)*               2162-42-21 to 24   30   Maleic acid   6   116.07       2162-42-25 to 28   30   Fumaric acid   7   116.07       2162-42-29 to 32   30   Tartaric acid   8   150.09       2162-42-33 to 36   30   Ethanesulfonic   9   110.13               acid               2162-42-37 to 40   30   Ethanedisulfonic   10   190.20               acid               2162-42-41 to 44   30   Citric acid   11   192.12       2162-42-45 to 48   30   Malic acid   12   134.09       2162-42-49 to 52   30   Lactic acid   13   90.08       2162-42-53 to 56   30   Aspartic acid   14   133.1       2162-42-57 to 60   30   Succinic acid   15   118.09       2162-42-61 to 64   30   Sodium   16   40.00               hydroxide               2162-42-65 to 68   30   Potassium   17   56.11               hydroxide               2162-42-69 to 72   30   Oxalic acid   18   90.03       2162-45-1 to 4   30   Magnesium   19   58.32               hydroxide                    
76 salt screening experiments of β-GPA with 19 different counter ions were set up with 30 mg of β-GPA. Sets of four vials for each counterion were set up with four different solvents (0.3 mL): ethanol:water (9:1), isopropanol, acetone:water (9:1) and acetonitrile.
 
     Appropriate amounts of β-GPA and the counterion were dissolved in the respective solvents and heated to 70-75° C. until dissolved. An additional 0.1 mL of water was added to the samples containing isopropanol, acetone:water (9:1) and acetonitrile. To samples containing L-aspartic acid, around 1.5 mL of water was required to dissolve the solids. After a clear solution was obtained, the samples were left for stirring at room temperature. Solids were observed in the following samples: 2163-42-4, 25, 26, 27, 28, 45 and 53 through 75. The solids were filtered and analyzed by XRPD immediately as wet sample. The samples that did not yield solids were placed in the oven at 50° C. for drying. The following samples resulted in solids after overnight drying: 2162-42-2, 1, 2, 3 and 21 through 24. The experiments with L-aspartic acid, sodium hydroxide, potassium hydroxide, and magnesium hydroxide resulted in the precipitation of either β-GPA or the counterion. All the experimental observations were recorded after every step and are listed in Table 12. 
     
       
         
           
               
             
               
                 TABLE 12 
               
             
            
               
                   
               
               
                 Results of Salt screening 
               
            
           
           
               
               
               
               
               
               
            
               
                 Sample ID 
                 Counterion 
                 Solvent 
                 After 24 hours 
                 After Drying 
                 XRPD 
               
               
                   
               
               
                 2162-42-1 
                 Hydrochloric 
                 EtOH:H 2 O (9:1) 
                 Clear Solution 
                 White Solid 
                 Pattern 1A 
               
               
                 2162-42-2 
                 Acid 
                 IPA 
                 Clear Solution 
                 White Solid 
                   
               
               
                 2162-42-3 
                   
                 Acetone:H 2 O (9:1) 
                 Clear Solution 
                 White Solid 
                   
               
               
                 2162-42-4 
                   
                 MeCN 
                 White Solid 
                 N/A 
                   
               
               
                 2162-42-5 
                 Hydrobromic 
                 EtOH:H 2 O (9:1) 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-6 
                 Acid 
                 IPA 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-7 
                   
                 Acetone:H 2 O (9:1) 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-8 
                   
                 MeCN 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-9 
                 Sulfuric Acid 
                 EtOH:H 2 O (9:1) 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-10 
                   
                 IPA 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-11 
                   
                 Acetone:H 2 O (9:1) 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-12 
                   
                 MeCN 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-13 
                 Phosphoric Acid 
                 EtOH:H 2 O (9:1) 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-14 
                   
                 IPA 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-15 
                   
                 Acetone:H 2 O (9:1) 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-16 
                   
                 MeCN 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-17 
                 Methanesulfonic 
                 EtOH:H 2 O (9:1) 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-18 
                 Acid 
                 IPA 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-19 
                   
                 Acetone:H 2 O (9:1) 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-20 
                   
                 MeCN 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-21 
                 Maleic Acid 
                 EtOH:H 2 O (9:1) 
                 Clear Solution 
                 White Solid 
                 Pattern 6A 
               
               
                 2162-42-22 
                   
                 IPA 
                 Clear Solution 
                 White Solid 
                   
               
               
                 2162-42-23 
                   
                 Acetone:H 2 O (9:1) 
                 Clear Solution 
                 White Solid 
                   
               
               
                 2162-42-24 
                   
                 MeCN 
                 Clear Solution 
                 White Solid 
                   
               
               
                 2162-42-25 
                 Fumaric Acid 
                 EtOH:H 2 O (9:1) 
                 White Solid 
                 N/A 
                 Pattern 7A 
               
               
                 2162-42-26 
                   
                 IPA 
                 White Solid 
                 N/A 
                   
               
               
                 2162-42-27 
                   
                 Acetone:H 2 O (9:1) 
                 White Solid 
                 N/A 
                   
               
               
                 2162-42-28 
                   
                 MeCN 
                 White Solid 
                 N/A 
                   
               
               
                 2162-42-29 
                 L-Tartaric Acid 
                 EtOH:H 2 O (9:1) 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-30 
                   
                 IPA 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-31 
                   
                 Acetone:H 2 O (9:1) 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-32 
                   
                 MeCN 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-33 
                 Ethanesulfonic 
                 EtOH:H 2 O (9:1) 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-34 
                 Acid 
                 IPA 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-35 
                   
                 Acetone:H 2 O (9:1) 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-36 
                   
                 MeCN 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-37 
                 Ethanedisulfonic 
                 EtOH:H 2 O (9:1) 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-38 
                 Acid 
                 IPA 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-39 
                   
                 Acetone:H 2 O (9:1) 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-40 
                   
                 MeCN 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-41 
                 Citric Acid 
                 EtOH:H 2 O (9:1) 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-42 
                   
                 IPA 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-43 
                   
                 Acetone:H 2 O (9:1) 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-44 
                   
                 MeCN 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-45 
                 L-Malic Acid 
                 EtOH:H 2 O (9:1) 
                 White Solid 
                 N/A 
                 Pattern 
               
               
                   
                   
                   
                   
                   
                 12A 
               
               
                 2162-42-46 
                   
                 IPA 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-47 
                   
                 Acetone:H 2 O (9:1) 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-48 
                   
                 MeCN 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-49 
                 L-Latic Acid 
                 EtOH:H 2 O (9:1) 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-50 
                   
                 IPA 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-51 
                   
                 Acetone:H 2 O (9:1) 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-52 
                   
                 MeCN 
                 Clear Solution 
                 Gel 
                 N/A 
               
               
                 2162-42-53 
                 L-Aspartic Acid 
                 EtOH:H 2 O (9:1) 
                 White Solid 
                 N/A 
                 L-Aspartic 
               
               
                 2162-42-54 
                   
                 IPA 
                 White Solid 
                 N/A 
                 Acid 
               
               
                 2162-42-55 
                   
                 Acetone:H 2 O (9:1) 
                 White Solid 
                 N/A 
                   
               
               
                 2162-42-56 
                   
                 MeCN 
                 White Solid 
                 N/A 
                   
               
               
                 2162-42-57 
                 Succinic Acid 
                 EtOH:H 2 O (9:1) 
                 White Solid 
                 N/A 
                 Pattern 
               
               
                 2162-42-58 
                   
                 IPA 
                 White Solid 
                 N/A 
                 15A 
               
               
                 2162-42-59 
                   
                 Acetone:H 2 O (9:1) 
                 White Solid 
                 N/A 
                   
               
               
                 2162-42-60 
                   
                 MeCN 
                 White Solid 
                 N/A 
                   
               
               
                 2162-42-61 
                 Sodium 
                 EtOH:H 2 O (9:1) 
                 White Solid 
                 N/A 
                 β-GPA 
               
               
                 2162-42-62 
                 Hydroxide 
                 IPA 
                 White Solid 
                 N/A 
                   
               
               
                 2162-42-63 
                   
                 Acetone:H 2 O (9:1) 
                 White Solid 
                 N/A 
                   
               
               
                 2162-42-64 
                   
                 MeCN 
                 White Solid 
                 N/A 
                   
               
               
                 2162-42-65 
                 Potassium 
                 EtOH:H 2 O (9:1) 
                 White Solid 
                 N/A 
                 β-GPA 
               
               
                 2162-42-66 
                 Hydroxide 
                 IPA 
                 White Solid 
                 N/A 
                   
               
               
                 2162-42-67 
                   
                 Acetone:H 2 O (9:1) 
                 White Solid 
                 N/A 
                   
               
               
                 2162-42-68 
                   
                 MeCN 
                 White Solid 
                 N/A 
                   
               
               
                 2162-42-69 
                 Oxalic Acid 
                 EtOH:H 2 O (9:1) 
                 White Solid 
                 N/A 
                 Pattern 
               
               
                 2162-42-70 
                   
                 IPA 
                 White Solid 
                 N/A 
                 18A 
               
               
                 2162-42-71 
                   
                 Acetone:H 2 O (9:1) 
                 White Solid 
                 N/A 
                   
               
               
                 2162-42-72 
                   
                 MeCN 
                 White Solid 
                 N/A 
                   
               
               
                 2162-45-1 
                 Magnesium 
                 EtOH:H 2 O (9:1) 
                 White Solid 
                 N/A 
                 β-GPA 
               
               
                 2162-45-2 
                 Hydroxide 
                 IPA 
                 White Solid 
                 N/A 
                   
               
               
                 2162-45-3 
                   
                 Acetone:H 2 O (9:1) 
                 White Solid 
                 N/A 
                   
               
               
                 2162-45-4 
                   
                 MeCN 
                 White Solid 
                 N/A 
               
               
                   
               
               
                 EtOH = ethanol; IPA = isopropanol; MeCN = acetonitrile 
               
            
           
         
       
     
       FIGS. 8 through 13  represents the XRPDs of the new crystalline forms isolated from slurry/slow evaporation experiments. 
     Stage II 
     The samples that resulted in gels in Stage I of the salt screening experiments were considered for Stage II, where another set of four new solvent systems (methanol, water, ethyl acetate, and trifluoroethanol) were used. The gels were dissolved in the respective solvents (Table 11) at 70° C. and were allowed to stir overnight. If a precipitate was observed the following day the stirring was stopped and XRPD analysis was carried out on the samples. If there was no precipitation, then the samples were dried in the oven at 50° C. Three experiments, hydrobromic acid in methanol and ethyl acetate and L-lactic acid in methanol, resulted in the precipitation β-GPA as confirmed by XRPD analysis. Crystalline forms were prepared with phosphoric acid (from ethyl acetate and trifluoroethanol), methanesulfonic acid (from ethyl acetate), ethanesulfonic acid (from all four solvents), and L-malic acid (from trifluoroethanol). 
     Example 3. Salt Screening Experiments in 2:1 (β-GPA:Acid) Molar Ratio 
     Salt screening experiments of β-GPA with maleic, fumaric, and oxalic acids in 2:1 (β-GPA:acid) ratio were set up. Around 0.3 mL of water was used to dissolve β-GPA (120 mg) and the counterion in 2:1 (β-GPA:acid) ratio at 90° C. for oxalic and maleic acid. However, for the experiment with fumaric acid, 0.2 mL of methanol was used to dissolve the counterion at 65° C. All the experiments resulted in the precipitation of white solids within 10 minutes. However, the vials were left for stirring over the weekend. Solids were filtered and rinsed with around 0.5 mL of isopropanol during filtration followed by XRPD analysis. Results are tabulated in Table 13. 
                     TABLE 13                  Results of Salt Screening Experiments in 2:1 (β-GPA:acid) molar ratio                                         Ratio of                Sample       β-GPA to   Solvent(s)           ID   Counterion   counterion   used   Result               2162-48-4   Fumaric   2:1   0.3 mL H 2 O to   1:1 salt           acid       dissolve    was formed                   β-GPA + 0.2   (Pattern 7A)                   mL methanol                       to dissolve                       fumaric acid           2162-48-5   Oxalic   2:1   0.3 mL H 2 O    Mixture of 1:1            acid           salt and β-GPA       2162-48-6   Maleic   2:1   0.3 mL H 2 O    2:1 salt was           acid           formed                       (Pattern 6B)                    
XRPD analysis revealed a new XRPD pattern for the maleic acid experiment (Pattern 6B,  FIG. 14 ). The 1H-NMR revealed that a 2:1 salt was formed between β-GPA and maleic acid ( FIG. 15 ).
 
     Example 4. Physical and Thermal Characterization of β-GPA 
     Hydrochloric Acid Salt 
     The DSC of β-GPA-HCl salt (Sample ID: 2162-42-2) revealed the presence of an endothermic event at around 135° C. followed by an exothermic event at around 185° C. and an endotherm at 265° C. ( FIG. 16 ). The exothermic event in the DSC arises from the recrystallization of the sample as confirmed by hot stage microscopy ( FIG. 17 ). The TGA analysis revealed a weight loss of around 11% from 31° C. to 210° C. 
     Phosphoric Acid Salt 
     Even though there were some differences in the XRPD patterns of two samples that resulted in crystalline material of β-GPA with phosphoric acid, the DSC and TGA analysis were almost identical. Both samples exhibited a melting point at around 138° C. and a weight loss &lt;1%. The phosphate analysis by Inductively Coupled Plasma/Optical Emission Spectrometry (ICP-OES) for the salt was found to be around 16% (Experimental value: 14%) and therefore it is likely a 1:1 salt. 
     Maleic Acid Salt (1:1 Salt) 
     The β-GPA-maleic acid salt (Sample ID: 2162-42-21) exhibited three endotherms at the following temperatures: 90, 124 and 141° C. ( FIG. 18 ). TGA analysis revealed a weight loss of around 1.2% from 31 to 105° C. (1st endotherm) and a weight loss of around 5.4% from 105 to 138° C. (2nd endotherm). 
     Maleic Acid Salt (2:1 Salt) 
     The β-GPA-maleic acid salt (Sample ID: 2162-48-6) exhibited two endotherms at 85 and 155° C. respectively. However, the dried sample exhibited only one endotherm at 155° C. From the DSC analysis it is evident that a hydrate was formed in the prior case whereas an anhydrous form was yielded as a result of drying. TGA analysis revealed a weight loss of &lt;0.1% from 31 to 145° C. 
     Fumaric Acid Salt (1:1 Salt) 
     β-GPA—fumaric acid salt (Sample ID: 2162-42-25) exhibited an endotherm at 171° C. ( FIG. 19 ) followed by possible decomposition of the salt. TGA analysis revealed a weight loss &lt;1% from 31° C. to 145° C. ( FIG. 20 ). The  1 H NMR of the 1:1 fumarate salt is shown in  FIG. 21 . 
     Fumaric Acid Salt (2:1 Salt) 
     β-GPA—fumaric acid salt (Sample ID: 2162-64-1) exhibited an endotherm at 187° C. and 251° C. ( FIG. 40 ). TGA analysis revealed a weight loss &lt;1% from 31° C. to 145° C. ( FIG. 41 ). The  1 H NMR of the 2:1 fumarate salt is shown in  FIG. 39 . 
     Ethanesulfonic Acid Salt 
     The crystalline material that resulted from the experiment between β-GPA and ethanesulfonic acid did not dry out completely even after drying for more than two days in the oven at 50° C. (all the four vials). 
     When the sample was analyzed by DSC, a broad endothermic event was observed followed by decomposition and the TGA also revealed a weight loss from the starting point (31° C.). The  1 H-NMR of the sample revealed no traces of ethanesulfonic acid in the sample. Therefore, the crystalline material could have been a product of chemical reaction between β-GPA and ethanesulfonic acid. 
     L-Malic Acid Salt 
     β-GPA—L-malic acid salt (Sample ID: 2162-42-45) exhibited an endotherm at 110° C. followed by possible decomposition of the salt. TGA analysis revealed a weight loss &lt;1% from 31° C. to 145° C. The  1 H-NMR of the salt confirmed it was a 1:1 salt. 
     Succinic Acid Salt (2:1 Salt) 
     The DSC of β-GPA—succinic acid salt (sample ID: 2162-42-59) revealed the presence of an endothermic event at around 130° C. followed by another endothermic event at around 175° C. An exothermic event was observed at around 179° C. ( FIG. 22 ) followed by an endothermic event at 232° C. To verify the endothermic and exothermic events in the DSC, hot stage microscopy was performed on the sample and illustrated in  FIG. 23 . The TGA analysis revealed a weight loss of around 0.4% from 31° C. to 135° C. and 13% from 135 to 215° C. ( FIG. 24 ). The  1 H-NMR revealed that the salt formed between β-GPA and succinic acid was in 2:1 (β-GPA:acid) molar ratio ( FIG. 25 ). 
     Oxalic Acid Salt (1:1 Salt) 
     The β-GPA—oxalic acid (Sample ID: 2162-42-69) when analyzed by DSC revealed a presence of an endothermic event at around 217° C. followed by an exothermic peak at around 224° C. and an endotherm at 268° C. as represented in  FIG. 26 . The TGA analysis revealed a weight loss of &lt;0.3% from 31 to 195° C. ( FIG. 27 ). When the material was observed under hot-stage microscope, at 216 to 226° C. there were very few crystals that appeared to melt however, there was no visible recrystallization event which was observed. From 268° C. melting of the crystals started to occur until 291° C. The  1 H-NMR of β-GPA oxalate is presented in  FIG. 28 . From the elemental analysis the stoichiometric ratio of β-GPA to oxalic acid was found to be 1:1 (Intertek). 
     Example 5. Optical Microscopic Imagery 
     Salts of β-GPA were also analyzed by optical microscopy. Optical microscopic images of β-GPA salts are presented from  FIG. 29A to 29J . As shown in  FIG. 30 , β-GPA fumarate (1:1) has a rod-like crystal morphology. 
     Example 6. Stability Testing of β-GPA Salts Under Stressed Conditions 
     The solid form stability of each salt was studied by XRPD under stressed conditions: wet, dry (45° C. under vacuum) and high humidity (RH &gt;95%). The results are tabulated in Table 14. 
     
       
         
           
               
             
               
                 TABLE 14 
               
             
            
               
                   
               
               
                 Results of Stability Studies 
               
            
           
           
               
               
               
               
            
               
                   
                 Wet_XRPD 
                 Dry_XRPD 
                 Humid_XRPD 
               
               
                 Salt 
                 pattern 
                 pattern 
                 pattern 
               
               
                   
               
               
                 β-GPA hydrochloride 
                 Pattern 1A 
                 Pattern 1A 
                 Deliquesce 
               
               
                 β-GPA phosphate 
                 Pattern 4A 
                 Pattern 4A 
                 Deliquesce 
               
               
                 β-GPA methanesulfonate 
                 Pattern 19A 
                 Pattern 19A 
                 Deliquesce 
               
               
                 β-GPA maleate (1:1) 
                 Pattern 6A 
                 Pattern 6A 
                 Pattern 6A 
               
               
                 Form I 
                   
                   
                   
               
               
                 β-GPA maleate (1:1) 
                 Pattern 6D 
                 Pattern 6D 
                 Pattern 6D 
               
               
                 Form II 
                   
                   
                   
               
               
                 β-GPA maleate (2:1) 
                 Pattern 6B 
                 Pattern 6C 
                 Pattern 6B 
               
               
                 β-GPA fumarate (1:1) 
                 Pattern 7A 
                 Pattern 7A 
                 Pattern 7A 
               
               
                 β-GPA malate (1:1) 
                 Pattern 12A 
                 Pattern 12A 
                 Deliquesce 
               
               
                 β-GPA succinate (2:1) 
                 Pattern 15A 
                 Pattern 15A 
                 Pattern 15A 
               
               
                 β-GPA oxalate (1:1) 
                 Pattern 18A 
                 Pattern 18A 
                 Pattern 18A 
               
               
                   
               
            
           
         
       
     
     Example 7. DVS Experiments 
     Four salts: β-GPA maleate (1:1) Form II, β-GPA fumarate (1:1), β-GPA maleate (2:1), β-GPA succinate (2:1) and β-GPA oxalate (1:1) were analyzed by DVS experiment followed by XRPD analysis of the sample at the end of the experiment. 
     1:1 β-GPA maleate (Pattern 6D) exhibited an increase in the moisture uptake from 60% RH and at around 95% RH there was around 25% moisture uptake, however, there was no form change after the end of the experiment as confirmed by XRPD. 
     1:1 β-GPA fumarate exhibited &lt;1% moisture uptake during the DVS experiment. XRPD analysis on the Post DVS sample revealed the presence of β-GPA peaks along with Pattern 7A ( FIG. 31 ). 
     Both the 2:1 β-GPA succinate and 1:1 β-GPA oxalate salts revealed &lt;0.5% moisture uptake during the DVS experiment and no form change was observed after the end of the experiment. 
     Example 8. Solid Form Stability of Salts in Different Solvents 
     Three salts were studied for solid form stability in water (disproportionation test), methanol, acetonitrile, and acetone:water (9:1) for 48 hours at room temperature. 
     1:1 β-GPA oxalate and 1:1 β-GPA fumarate salts retained their XRPD pattern after 48 hours slurry in water. 2:1 β-GPA succinate started showing up peaks from β-GPA after 6 hours slurry in water and thus the experiment was stopped after 6 hours. 
     After slurrying the 1:1 β-GPA fumarate and 1:1 β-GPA oxalate salts in methanol, acetonitrile, and acetone:water (9:1), the salts were found to retain their XRPD pattern. 
     After slurrying the 2:1 β-GPA succinate in methanol and acetonitrile, the salt was found to retain its XRPD pattern. However, the slurry in acetone:water (9:1) revealed the presence of β-GPA after 48 hours. 
     Example 9. Solid Form Stability of Salts at 40° C. and 75% Humidity 
     Solid form stability studies of β-GPA fumarate, succinate, and oxalate were carried out at 40° C. and 75% RH for seven days. Around 30 mg of the salts were placed in 4 mL vials which were placed in a saturated solution of sodium chloride (2 mL) with lids closed at 40° C. The samples were left for a week followed by XRPD analysis of the salts. All three salts retained their original XRPD pattern. 
     Example 10. Purity of Salts 
     The purity of β-GPA salts was determined by HPLC using the method below. 
     The HPLC method is described below: 
     Column: SeQuant ZIC Hilic PEEK column (250×4.6 mm, 5 μm) 
     Mobile Phase A: 0.02M Phosphate buffer, pH 3.0 
     The mobile phase was prepared by dissolving 2.72 g of monobasic potassium phosphate in  1 L of deionized water and the adjusting the desired pH by 85% (w/w) phosphoric acid. 
     Mobile Phase B: 100% Acetonitrile 
     Gradient used:
         Time (minutes) A % B %   0 25 75   15.0 25 75   23.0 80 20   25.0 80 20   25.1 25 75   30.0 25 75       

     Flow rate: 1 mL/min 
     Injection volume: 10 μL 
     Detector wavelength: 210 nm 
     Run time: 30 minutes 
     Column temperature: 40° C. 
     Diluent: Acetonitrile:water (1:1) 
     The counterions were also analyzed by HPLC under the same concentrations as they were present in the respective salts. 
     The purity of β-GPA salts is listed in Table 15. 
     
       
         
           
               
             
               
                 TABLE 15 
               
             
            
               
                   
               
               
                 Purity of Salts 
               
            
           
           
               
               
               
            
               
                   
                 β-GPA salt 
                 Purity by HPLC 
               
               
                   
               
               
                   
                 β-GPA fumarate (1:1) 
                 97.7% 
               
               
                   
                 β-GPA succinate (2:1) 
                 98.1% 
               
               
                   
                 β-GPA oxalate (1:1) 
                 98.4% 
               
               
                   
               
            
           
         
       
     
     Example 11. Scale-Up of Salts 
     Oxalate Salt 
     Around 7.2 g (0.055 moles) of β-GPA was added to an EasyMax reaction vessel containing 30 mL water. The reaction mixture was stirred at 90° C. until a clear solution was obtained. To this solution, around 5.4 g (0.06 moles) of oxalic acid was added slowly and the temperature of the reactor was brought down to 20° C. Around 20 mL of isopropanol was added to the reaction mixture was left for overnight stirring. Sample ID: 2162-64-2. 
     The following day, the slurry was filtered and the solid was washed twice with 10 mL of isopropanol. The cake was placed in a vacuum oven at 45° C. for drying. Yield=11.4 g (94%). The solid was analyzed by XRPD and β-GPA oxalate salt, Pattern 18A, formation was confirmed. 
     Succinate Salt 
     Around 72 g (0.55 moles) of β-GPA was added to 400 mL of ethanol:water (9:1) in 500 mL jacketed vessel at 75° C. and a slurry was made. To this, a slurry of succinic acid, prepared by adding 71.2 g (0.6 moles) in 200 mL ethanol:water (9:1) at 65° C., was added. The temperature of the reactor was brought down to 18° C. and the reaction mixture was left for overnight stirring. Sample ID: 2162-62-1. 
     The following day, the slurry was filtered and the solid was washed twice with 20 mL of isopropanol. The cake was placed in a vacuum oven at 45° C. for drying. Yield=101.3 g (97%). The solid was analyzed by XRPD and the formation of β-GPA succinate (Pattern 15 A) was confirmed. 
     Fumarate Salt 
     Around 48 g (0.37 moles) of β-GPA was added to 120 mL of water in 500 mL jacketed vessel at 90° C. and a clear solution was obtained. To this solution, a solution of fumaric acid, prepared by dissolving 46.8 g (0.40 moles) in 220 mL methanol at 65° C., was added. The temperature of the reactor was brought down to 18° C. and the reaction mixture was left for overnight stirring. Sample ID: 2162-64-1. 
     The following day, the slurry was filtered and the solid was washed twice with 20 mL of isopropanol. The cake was placed in a vacuum oven at 45° C. for drying. Yield=61.5 g (90%). The solid was analyzed by XRPD and the formation of β-GPA fumarate (Pattern 7A) was confirmed. After NMR analysis this salt was determined to be the 2:1 fumarate salt. After further analysis, it was determined that the 2:1 and 1:1 fumarate salts have similar XRPD patterns. 
     Example 12. Determination of Bulk and Tapped Density 
     The bulk density of β-GPA oxalate (Pattern 18 B), succinate (Pattern 15A), and fumarate (Pattern 7A) were determined by pouring in a known amount of salt (g) into a measuring cylinder. The volume (V i ) occupied by the salt was recorded and the bulk density (ρ B ) was determined using equation 1.
 
ρ B   =g/V   i   (1)
 
     The tapped densities of the salts were determined using a Tap density analyzer. A known amount of salt was poured (g) into a measuring cylinder and the initial volume was recorded and tapped using a Tap density analyzer. The final volume (V f ) after tapping was recorded and the tapped density (ρ T ) was calculated by using equation 2.
 
ρ T   =g/V   f   (2)
 
     Table 16 lists the bulk and tapped density of β-GPA and salts thereof. 
     
       
         
           
               
             
               
                 TABLE 16 
               
             
            
               
                   
               
               
                 Bulk and Tapped Densities 
               
            
           
           
               
               
               
            
               
                 Sample 
                 Bulk density (ρB) 
                 Tapped density (ρT) 
               
               
                   
               
               
                 β-GPA 
                 0.389 g/cc 
                 0.627 g/cc 
               
               
                 β-GPA oxalate (1:1) 
                 0.505 g/cc 
                 0.623 g/cc 
               
               
                 β-GPA succinate (2:1) 
                 0.405 g/cc 
                 0.472 g/cc 
               
               
                 β-GPA fumarate (2:1) 
                 0.576 g/cc 
                 0.613 g/cc 
               
               
                   
               
            
           
         
       
     
     Example 13. Determination of Carr&#39;s Index and Hausner Ratio 
     Carr&#39;s index or Carr&#39;s compressibility index (C) is an indication of the compressibility of a powder. It can be calculated using the equation below:
 
Carr&#39;s index ( C )=100( V   i   −V   f )/ V   i   (3)
 
A Carr&#39;s index greater than 25 is considered to be an indication of poor flowability while a value below 15 is an indication of good flowability.
 
     The Hausner ratio is a number that is correlated to the flowability of a powder or granular material. It is calculated by using the equation below:
 
Hausner ratio= V   i   /V   f   (4)
 
     Table 17 lists the Carr&#39;s index and Hausner ratio corresponding to the flow character of a powder proposed by R. L. Carl. 
     
       
         
           
               
             
               
                 TABLE 17 
               
             
            
               
                   
               
               
                 Flow Characteristics Based on Carr&#39;s Index and Hausner Ration 
               
            
           
           
               
               
               
               
            
               
                   
                 Carr index 
                 Flow character 
                 Hausner ratio 
               
               
                   
                   
               
               
                   
                  1-10 
                 Excellent 
                 1.00-1.11 
               
               
                   
                 11-15 
                 Good 
                 1.12-1.18 
               
               
                   
                 16-20 
                 Fair 
                 1.19-1.25 
               
               
                   
                 21-25 
                 Passable 
                 1.26-1.34 
               
               
                   
                 26-31 
                 Poor 
                 1.35-1.45 
               
               
                   
                 32-37 
                 Very poor 
                 1.46-1.59 
               
               
                   
                 &gt;38 
                 Very very poor 
                 &gt;1.60 
               
               
                   
                   
               
            
           
         
       
     
     Table 18 lists the Carr&#39;s index and Hausner ratio for β-GPA and salts thereof. 
     
       
         
           
               
             
               
                 TABLE 18 
               
             
            
               
                   
               
               
                 Carr&#39;s Index and Hausner Ratio for β-GPA and Salts Thereof 
               
            
           
           
               
               
               
               
            
               
                 Sample 
                 Carr index 
                 Flow character 
                 Hausner ratio 
               
               
                   
               
               
                 β-GPA 
                 37.9 
                 Very very poor 
                 1.610 
               
               
                 β-GPA oxalate (1:1) 
                 18.7 
                 Fair 
                 1.23  
               
               
                 (Pattern 18A, 
                   
                   
                   
               
               
                 original salt) 
                   
                   
                   
               
               
                 β-GPA succinate (2:1) 
                 14.3 
                 Good 
                 1.167 
               
               
                 (Pattern 15A) 
                   
                   
                   
               
               
                 β-GPA fumarate (2:1) 
                  5.9 
                 Excellent 
                 1.063 
               
               
                 (Pattern 7A) 
               
               
                   
               
            
           
         
       
     
     Example 14. Flowability Measurement Using Hanson Flodex Unit 
     Method: A cylindrical vessel is secured to the stand and above that a funnel is also secured such that the bottom of the funnel is close to the vessel. A powder load of ≈50-60 g is then poured through the funnel into the middle of the cylinder. The lever device is pulled to open the hole in the disk quickly and without vibration. If a powder slowly flows through the small-diameter holes, leaving a cavity shaped like an upside-down, truncated cone, the test is considered positive. If a powder flocculates in bulk and falls abruptly, forming a cylindrical cavity, the test is considered negative. If a powder does not fall through the small-diameter holes, the test is considered negative. If the experiment is negative, the powder is tested again with a disk having a larger hole. Tables 19-22 list the flowability test results for β-GPA and salts thereof. 
     
       
         
           
               
             
               
                 TABLE 19 
               
             
            
               
                   
               
               
                 Flowability Test Results for β-GPA 
               
            
           
           
               
               
               
            
               
                   
                 Disc pore 
                   
               
               
                 Run # 
                 Size mm 
                 Did solid pass? 
               
               
                   
               
               
                 1 
                 18 
                 No 
               
               
                 2 
                 20 
                 No 
               
               
                 3 
                 28 
                 No 
               
               
                 4 
                 32 
                 Yes, but the powder fell abruptly forming a  
               
               
                   
                   
                 cylindrical cavity (flocculation). Thus, the test 
               
               
                   
                   
                 was considered negative. 
               
               
                 5 
                 30 
                 No 
               
               
                 6 
                 34 
                 Yes 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 20 
               
             
            
               
                   
               
               
                 Flowability Test Results for the Oxalate Salt 
               
            
           
           
               
               
               
            
               
                   
                 Disc pore 
                 Did solid 
               
               
                 Run # 
                 Size mm 
                 pass? 
               
               
                   
               
               
                 1 
                 12 
                 No 
               
               
                 2 
                 18 
                 No 
               
               
                 3 
                 24 
                 No 
               
               
                 4 
                 30 
                 Yes 
               
               
                 5 
                 28 
                 Yes 
               
               
                 6 
                 26 
                 Yes 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 21 
               
             
            
               
                   
               
               
                 Flowability Test Results for the Succinate Salt 
               
            
           
           
               
               
               
            
               
                   
                 Disc pore 
                 Did solid 
               
               
                 Run # 
                 Size mm 
                 pass?  
               
               
                   
               
               
                 1 
                 24 
                 Yes 
               
               
                 2 
                 22 
                 Yes 
               
               
                 3 
                 20 
                 Yes 
               
               
                 4 
                 18 
                 Yes 
               
               
                 5 
                 10 
                 Yes 
               
               
                 6 
                  8 
                 Yes 
               
               
                 7 
                  7 
                 Yes 
               
               
                 8 
                  5 
                 No 
               
               
                 9 
                  6 
                 No 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 22 
               
             
            
               
                   
               
               
                 Flowability Test Results for the Fumarate Salt 
               
            
           
           
               
               
               
            
               
                   
                 Disc pore 
                 Did solid 
               
               
                 Run # 
                 Size mm 
                 pass?  
               
               
                   
               
               
                 1 
                 12 
                 Yes 
               
               
                 2 
                  6 
                 Yes 
               
               
                 3 
                  4 
                 No 
               
               
                 4 
                  5 
                 Yes 
               
               
                   
               
            
           
         
       
     
     Example 15. DVS and Stability at High Humidity of the 2:1 Fumarate Salt 
     Sample 2162-64-1 was analyzed by DVS in triplicate and the post DVS samples were characterized by XRPD to identify the form at the end of the experiment. In all the three experiments, the moisture uptake by β-GPA fumarate was found to be less than 0.1%. In all the three experiments, the XRPDs were found to be identical to β-GPA fumarate (Pattern 7A) and no appearance of β-GPA peaks were observed, unlike sample 2162-42-3 post DVS ( FIG. 30 ). 
     The solid form stability of 2162-64-1 was also studied at RH &gt;95% at room temperature. β-GPA fumarate was found to retain its original XRPD pattern (Pattern 7A) after 48 hours. 
     Summary of Salt Screening Experiments 
     Ten salts of β-GPA namely, β-GPA HCl. β-GPA phosphate, β-GPA mesylate, β-GPA maleate (1:1, Pattern 6A), β-GPA maleate (1:1, Pattern 6D), β-GPA maleate (2:1, Pattern 6B), β-GPA fumarate, β-GPA malate, β-GPA succinate and β-GPA oxalate, were isolated from salt screening experiments (Stages I and II). 
     Of the ten salts, six of the salts, β-GPA HCl, β-GPA phosphate, β-GPA mesylate, β-GPA maleate (1:1, Pattern 6A), β-GPA malate, and β-GPA maleate (2:1, Pattern 6B), were excluded from further studies owing to their deliquescent nature, non-reproducibility, or purity issues. 
     Foursalts of β-GPA were selected after performing the DVS experiments: β-GPA maleate (1:1), fumarate (1:1), succinate (2:1) and oxalate (1:1) and the form stability was determined by XRPD. 
     β-GPA fumarate, succinate and oxalate retained their XRPD after the DVS experiment. However, β-GPA fumarate revealed the presence of two peaks from the β-GPA indicating dissociation of the salt. 
     The scaled-up sample of β-GPA fumarate, which was determined to be the 2:1 salt, was again analyzed by DVS three times and in these experiments the sample did not exhibit any dissociation of the salt. Indicating that the 2:1 fumarate salt is more stable than the 1:1 salt. Additional solid form stability testing of β-GPA fumarate at RH &gt;95% at 20° C. also revealed that the salt was stable. 
     The purity assessment for the salts was carried out by HPLC and the purity of the salts was as follows: β-GPA fumarate—97.7%, β-GPA succinate—98.1% and β-GPA oxalate—98.4%. 
     Stability studies of salts were also carried out by slurrying them in water (test for disproportionation), methanol, acetonitrile, and acetone:water (9:1) for 48 hours at room temperature. The following results were obtained:
         β-GPA maleate, fumarate and oxalate retained their XRPD patterns after 48 hours slurry in water while, β-GPA succinate showed two peaks from β-GPA after 6 hours slurry in water.   After 48 hours slurry, β-GPA maleate in methanol and acetonitrile was found to retain its XRPD pattern. However, the slurry in acetone:water (9:1) matched with the original pattern of the salt (Pattern 6D) along with some additional peaks in the XRPD analysis.   After 48 hours slurry, β-GPA succinate in methanol and acetonitrile salt was found to retain its original form. However, the slurry in acetone:water (9:1) revealed the presence of β-GPA after 48 hours along with the salt by XRPD analysis.       

     Solid form stability studies of β-GPA fumarate, succinate, and oxalate were carried out at 40° C. and 75% RH for seven days. All the three salts were found to be stable and retained their original XRPD patterns. 
     Three salts of β-GPA were scaled up to 60-100 g scale. β-GPA fumarate and succinate were scaled-up successfully; however β-GPA oxalate resulted in an ethanol solvate of the salt (confirmed by  1 H-NMR). The mole percent of ethanol to β-GPA was found to be 0.22 to 1 (Pattern 18 B). 
     Nevertheless, by changing the solvent system from ethanol:water (9:1) to water and isopropanol the original β-GPA oxalate salt was produced, but the XPRD pattern confirmed the presence of new additional peaks in minor quantities. 
     The bulk and tapped densities of β-GPA and its salts: β-GPA oxalate (Patterns 18A and B), fumarate, and succinate were determined using density analyzer unit. Likewise, flowability measurements for the salts were measured using Hanson Flodex unit. 
     From the experimental data β-GPA and β-GPA oxalate (Pattern 18B) were found to exhibit poor flow character whereas, β-GPA oxalate (Pattern 18A) was fair whilst, β-GPA succinate was good, and β-GPA fumarate exhibited excellent flow characteristics. 
     Based on the solid form stability, reproducibility, density and flowability properties the 2:1 β-GPA fumarate salt appears to have the best properties of the salts screened. 
     Example 16. Polymorph Screening of the 2:1 β-GPA Fumarate Salt 
     Solid Form Stability of the 2:1β-GPA Fumarate Salt 
     The solid form stability of β-GPA fumarate was studied at various temperature/humidity conditions as listed in Table 23 for a week using saturated salt solution chambers. The samples were analyzed by XRPD after a week. The XRPD analysis of the stability samples for β-GPA fumarate under various temperature/RH conditions indicated that β-GPA fumarate retained the original XRPD pattern (Pattern 7A) 
     
       
         
           
               
             
               
                 TABLE 23 
               
             
            
               
                   
               
               
                 Stability Study Results 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Temperature 
                 Relative 
                 Saturated salt 
                   
               
               
                 Sample ID 
                 (° C.) 
                 humidity 
                 solution* 
                 XRPD 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 2162-75-1 
                 20 
                  43% 
                 Potassium carbonate 
                 Pattern 7A 
               
               
                 2162-75-2 
                 20 
                  59% 
                 Sodium bromide 
                 Pattern 7A 
               
               
                 2162-75-3 
                 20 
                  73% 
                 Sodium chloride 
                 Pattern 7A 
               
               
                 2162-75-4 
                 40 
                  82% 
                 Potassium chloride 
                 Pattern 7A 
               
               
                 2162-75-5 
                 60 
                  50% 
                 Sodium bromide 
                 Pattern 7A 
               
               
                 2162-75-6 
                 60 
                  80% 
                 Potassium chloride 
                 Pattern 7A 
               
               
                 2162-75-7 
                 20 
                 &gt;95% 
                 Water 
                 Pattern 7A 
               
               
                   
               
            
           
         
       
     
     Solubility of the 2:1 β-GPA Fumarate Salt 
     Solubility of β-GPA fumarate was measured gravimetrically in fifteen different solvents and solvent mixtures at 15 and 45° C. About 100 mg of the compound was dispensed in ten volumes (1 mL) of the solvent/solvent mixture and slurried for 48 hours. Table 24 represents the solubility of β-GPA fumarate in different solvents. After 48 hours the vials were centrifuged. The supernatant was collected and left for slow evaporation under vacuum at 45° C. and solubility was determined. The solids obtained after centrifugation and evaporation were analyzed by XRPD. The XRPD analysis of the precipitates after 48 hours slurries revealed no form transformations for 2:1 β-GPA fumarate. 
     
       
         
           
               
             
               
                 TABLE 24 
               
             
            
               
                   
               
               
                 Results of Solubility Study 
               
            
           
           
               
               
               
               
            
               
                   
                 Temp  
                   
                 Solubility  
               
               
                 Solvent 
                 (° C.) 
                 Sample ID 
                 (mg/mL) 
               
               
                   
               
            
           
           
               
               
               
               
            
               
                 Water 
                 15 
                 2162-74-1A 
                 30 
               
               
                   
                 45 
                 2162-74-1B 
                 &gt;100 
               
               
                 IPA:H 2 O (9:1) 
                 15 
                 2162-74-2A 
                 1.64 
               
               
                   
                 45 
                 2162-74-2B 
                 2.1 
               
               
                 MeOH:H 2 O (9:1) 
                 15 
                 2162-74-3A 
                 9.2 
               
               
                   
                 45 
                 2162-74-3B 
                 11.2 
               
               
                 Acetone:H 2 O (9:1) 
                 15 
                 2162-74-4A 
                 2.5 
               
               
                   
                 45 
                 2162-74-4B 
                 4.1 
               
               
                 THF:H 2 O (9:1) 
                 15 
                 2162-74-5A 
                 2.08 
               
               
                   
                 45 
                 2162-74-5B 
                 4.12 
               
               
                 MeOH 
                 15 
                 2162-74-6A 
                 ~1 
               
               
                   
                 45 
                 2162-74-6B 
                 2.73 
               
               
                 EtOH 
                 15 
                 2162-74-7A 
                 &lt;1 
               
               
                   
                 45 
                 2162-74-7B 
                 &lt;1 
               
               
                 IPA 
                 15 
                 2162-74-8A 
                 &lt;1 
               
               
                   
                 45 
                 2162-74-8B 
                 &lt;1 
               
               
                 EtOAc 
                 15 
                 2162-74-9A 
                 &lt;1 
               
               
                   
                 45 
                 2162-74-9B 
                 &lt;1 
               
               
                 MeCN 
                 15 
                 2162-74-10A 
                 &lt;1 
               
               
                   
                 45 
                 2162-74-10B 
                 &lt;1 
               
               
                 Acetone 
                 15 
                 2162-74-11A 
                 &lt;1 
               
               
                   
                 45 
                 2162-74-11B 
                 &lt;1 
               
               
                 DCM 
                 15 
                 2162-74-12A 
                 &lt;1 
               
               
                   
                 45 
                 2162-74-12B 
                 0.5 
               
               
                 Heptane 
                 15 
                 2162-74-13A 
                 &lt;1 
               
               
                   
                 45 
                 2162-74-13B 
                 &lt;1 
               
               
                 TBME 
                 15 
                 2162-74-14A 
                 3.0 
               
               
                   
                 45 
                 2162-74-14B 
                 28.9 
               
               
                 H 2 O:MeOH:IPA  
                 15 
                 2162-74-15A 
                 &lt;1 
               
               
                 (3:5.5:5) 
                 45 
                 2162-74-15B 
                 &lt;1 
               
               
                   
               
               
                 IPA = isopropanol; EtOH = ethano; EtOAc = ethyl acetate; DCM = dichloromethane; TBME = t-butylmethyl ether; MeOH = methanol; MeCN = Acetonitrile 
               
            
           
         
       
     
     For ten of fourty-five samples the XRPDs after the slow evaporation of the filtrates from the slurry experiments resulted in Pattern 7A. Seventeen samples did not have enough solids for XRPD analysis. Sample 2162-74-5B resulted in a new crystalline form after slow evaporation of the filtrate and sample 2162-74-6B resulted in mixed XRPDs of Patterns 7A and 7B ( FIG. 32 ). 
     β-GPA fumarate was slurried in tetrahydrofuran:water (1:1) for 48 hours. The filtrate was set up for evaporation at 45° C. under vacuum, and after overnight evaporation an off-white solid was obtained. Both the solids from the slurry and the solids obtained after slow evaporation were analyzed by XRPD ( FIG. 33 ). 
     Pattern 7B, obtained by slow evaporation (45° C.) of the filtrate of β-GPA fumarate from the slurry experiment in tetrahydrofuran:water (1:1), was analyzed by DSC and  1 H-NMR. The DSC revealed the presence of an endotherm at 161° C. and also traces of Pattern 7A (the original β-GPA fumarate salt). 
     Anti-Solvent Addition Experiments 
     Anti-solvent addition experiments for 2:1 β-GPA fumarate were performed by using different anti-solvents. A given amount of 2:1 β-GPA fumarate was dissolved in the solvent at 50° C. Around 1 mL of ice cold anti-solvent was added to salt solution and continued stirring in ice bath for 2 hours followed by overnight stirring at 20° C. None of the experiments resulted in a new form of β-GPA fumarate. 
     Neat and Solvent Drop Grinding Experiments 
     Neat and solvent drop grinding experiments were also performed as a part of polymorph screening. Around 30 mg of the sample was ground in the presence of 20 μL of solvent (tetrahydrofuran, isopropanol, acetone, water, or t-butylmethylether) for 5 minutes using mortar and pestle. After grinding, the samples were analyzed by XRPD. All the experiments resulted in XRPDs that were identical to Pattern 7A. 
     Attempts to Generate Amorphous Form of β-GPA Fumarate 
     1 g of 2:1 β-GPA fumarate was dissolved in 10 mL of water at 50° C. in a round bottom flask. The round bottom flask was placed in the dry ice/acetone cooling bath (−78° C.) until the sample solidified followed by lyophilization for 48 hours. A white solid was obtained which was analyzed by XRPD, DSC and  1 H-NMR. Sample ID: 2162-84-1. The XRPD analysis revealed a new XRPD pattern for 2162-84-1 (Pattern 7C) as shown in  FIG. 34 . The 1H-NMR of 2162-84-1 revealed that the solid obtained after lyophilization resulted in the formation of a polymorph of 2:1 β-GPA fumarate ( FIG. 35 ). However, the microscopic image of the sample revealed the presence of some amorphous material. It could be possible that excess of fumaric acid after the formation of 2:1 β-GPA fumarate salt might have transformed to amorphous as seen in the microscopic image of the lyophilized sample 
     To confirm the above hypothesis the following experiments (Table 25) were performed on the lyophilized sample (Pattern 7C): 
     
       
         
           
               
             
               
                 TABLE 25 
               
             
            
               
                   
               
               
                 Results of Experiments Performed on 2:1 Fumarate Salt 
               
            
           
           
               
               
               
            
               
                 Sample ID 
                 Experiment 
                 Result 
               
               
                   
               
               
                 2162-86-2 
                 10 mg of Pattern 7C (lyophilized sample)  
                 Pattern 7C to 
               
               
                   
                 and Pattern 7A were mixed in a vial and  
                 Pattern 7A 
               
               
                   
                 left undisturbed at room temperature (48 
                   
               
               
                   
                 hours). The mixture was later analyzed  
                   
               
               
                   
                 by XRPD. 
                   
               
               
                 2162-86-3 
                 Vial containing 20 mg of Pattern 7C was  
                 Pattern 7C to 
               
               
                   
                 heated at 50° C. 5-10 minutes and later  
                 Pattern 7A 
               
               
                   
                 analyzed by XRPD. 
                   
               
               
                 2162-86-4 
                 Vial containing 20 mg of Pattern 7C was  
                 Pattern 7C to 
               
               
                   
                 placed in a humidity chamber with RH  
                 Pattern 7A 
               
               
                   
                 &gt;95% for 48 hours. Sample was later  
                   
               
               
                   
                 analyzed by XRPD. 
                   
               
               
                 2162-87-1 
                 50 mg of Pattern 7C was slurried in  
                 Pattern 7C to 
               
               
                   
                 0.2 mL of water. 
                 Pattern 7A 
               
               
                   
                   
                 (within 10  
               
               
                   
                   
                 minutes) 
               
               
                   
               
            
           
         
       
     
     The DSC of the lyophilized sample revealed the presence of an exothermic event (possible recrystallization or solid phase transformation) followed by two endothermic events ( FIG. 36 ). The first endothermic event could be the 2:1 β-GPA fumarate salt followed by the melting of possible side product which might have formed after the melting of 2:1 β-GPA fumarate salt. 
     1 g of 2:1 β-GPA fumarate was dissolved in 10 mL of water at 50° C. and was placed under vacuum at 100° C. for fast evaporation. Sample ID: 2162-84-2. The solid obtained was analyzed by XRPD and sample was found to retain the original β-GPA fumarate powder pattern (Pattern 7A). 
     Temperature Cycling Experiments 
     The following (Table 26) experiments were performed to isolate possible polymorphic forms of 2:1 β-GPA fumarate. 
                     TABLE 26                  Temperature Cycling Results                         Sample ID   Experiment   Result               2162-84-3   Vial containing 50 mg of β-GPA    Pattern 7A           fumarate was placed in vacuum                oven at 130° C. for 2 hours and                brought to room temperature (RT)                and placed back in the oven at                130° C. for 48 hours and again to                RT.           2162-84-4   Vial containing 50 mg of β-GPA    Pattern 7A           fumarate was placed on the hot                plate at 50° C. for 2 hours and                brought to room temperature                and placed back in the oven at                50° C. for 48 hours and again                to RT.           2162-84-5   Vial containing 50 mg of β-GPA    Pattern 7A           fumarate was placed in the dry                ice-acetone mixture for 30                minutes and was brought to room                temperature and again placed                back in the dry ice-acetone                mixture for additional 30 min and                again to RT.           2162-84-6   50 mg of β-GPA fumarate was    Pattern 7A           heated in a vial to 150° C. and               brought to room temperature. This                cycle was repeated three times and                the sample was analyzed later by                XRPD.           2162-84-7   50 mg of β-GPA fumarate was    The started           heated in an aluminum cup to   turned yellow            165° C. and immediately placed    to brown            in dry ice/acetone cooling bath for    in color           15 min. Later, the sample was    upon heating.           analyzed later by XRPD.   Pattern 7D                    
Heating of β-GPA fumarate (2162-84-7) at 160-165° C. resulted in a yellow to brownish solid (possible side reaction followed by decomposition) which was further analyzed by 1H-NMR and XRPD.
 
     Several cooling experiments were conducted all of which resulted in no form change, or resulted in the isolation of fumaric acid-β form or a mixture of fumaric acid-α and β forms concomitantly. 
     Lyophilization Experiments 
     Around 264 mg of β-GPA and 118 mg fumaric acid were dissolved in 10 mL of water at 65° C. The solution was solidified using dry ice-acetone mixture followed by freeze drying for 48 hours. This resulted in the isolation of a polymorph of the 2:1 salt. 
     Diffusion Experiments 
     Diffusion experiments for 2:1 β-GPA fumarate were set up dissolving around 1 g of the salt in 10 mL of water. For every diffusion experiment, 1 mL of the above solution was dispensed in a small 4 mL vial and was placed in a 20 mL scintillation vial containing the different solvents. None of the experiments resulted in a new form of β-GPA fumarate. 
     Reverse Anti-Solvent Addition Experiments 
     Reverse anti-solvent addition experiments for 2:1 β-GPA fumarate were performed by using different anti-solvents. A given amount of 2:1 β-GPA fumarate was dissolved in 1 mL of solvent at 40° C. This solution was added to a known amount of an anti-solvent and stirred at room temperature until solids precipitated out. None of the experiments resulted in a new form of β-GPA fumarate. 
     Summary of Polymorph Screening Experiments 
     Based on the available data obtained from the screening experiments, Pattern 7A appears to be the most stable form. 
     Example 17. Raman Spectroscopy of 2:1 β-GPA Fumarate Salt 
     Raman spectroscopy of the 2:1 β-GPA fumarate salt (Pattern 7A) was carried out on a Bruker IFS 66V/S FT-IR/FT-Raman spectrometer equipped with a 1064 nm laser ( FIG. 37 ). The peak list of the Raman spectra is listed in Table 27. 
     
       
         
           
               
             
               
                 TABLE 27 
               
             
            
               
                   
               
               
                 Raman Spectra Peak List 
               
               
                 2:1 fumarate β-GPA fumarate salt 
               
            
           
           
               
               
            
               
                 Raman Shift (cm-1) 
                 Functional group 
               
               
                   
               
            
           
           
               
               
            
               
                 3300.48 
                 COOH/NH 
               
               
                 3188.58 
                   
               
               
                 3049.73 
                 C═C—H 
               
               
                 2941.74 
                 CH2 
               
               
                 2886.78 
                   
               
               
                 1713.28 
                 C═O, υ(C═C), υ(C═N) 
               
               
                 1653.49 
                   
               
               
                 1483.79 
                 N═N-R 
               
               
                 1421.11 
                 N═N 
               
               
                 1382.54 
                   
               
               
                 1305.4 
                 Alkene In-plane bending 
               
               
                 1268.76 
                   
               
               
                 1190.66 
                 Alkene out of plane bending 
               
               
                 1084.59 
                 C—C (acid) 
               
               
                 997.81 
                   
               
               
                 896.56 
                 υ(O—O) 
               
               
                 681.53 
                 Aliphatic chain vibrations 
               
               
                 625.6 
                   
               
               
                 555.21 
                   
               
               
                 486.79 
                 δ(CC) aliphatic chains 
               
               
                   
               
            
           
         
       
     
     Example 18. Single Crystal Analysis of 2:1 β-GPA Fumarate Salt 
     SCXRD analysis of a crystal form of the 2:1 fumarate salt confirms the 2:1 stoichiometric between the β-GPA and fumaric acid. 2:1 fumarate salt of β-GPA crystallizes in monoclinic crystal system with P2 1 /n space group. The asymmetric unit consists of two β-GPA and one fumaric acid molecules ( FIG. 42A ) whilst, the unit cell consists of four fumaric acid and eight β-GPA molecules ( FIG. 42B ). SCXRD data was collected at room temperature (25° C.). 
     Unit Cell Parameters: 
     Crystal System: Monoclinic 
     Space Group: P 2 1 /n 
     a=12.4541(5) A 
     b=9.5447(4) A 
     c=14.4013(6) A 
     α=90°, β=100.469(2)°, γ=90° 
     Cell Volume: 1683.39 Å 3    
     The carboxylates moieties of two fumaric acid and two NH 2  moieties of two β-GPA molecules interact via O...NH hydrogen bonding thus, forming a four membered ring. The carboxylates moieties of fumaric acid also hydrogen bond with another adjacent β-GPA molecule through O...OH with a bond distance of 2.545 Å. The carboxylic acid moiety of the same β-GPA molecule interacts with the neighboring β-GPA molecule via O...NH hydrogen bond (2.835 Å).  FIG. 42C  below describes the several other hydrogen bonding interactions with the bond distances. 
     The overall hydrogen bonding between β-GPA and fumaric acid results in the formation of 2-dimensional planar sheets which interacts via weak Van der Waals forces ( FIG. 42D ). 
     Example 19. Calculated XRPD Based on Single Crystal Analysis 
     As shown in  FIGS. 43A-C , the experimental XRPD pattern (NP-2162-163-3) of the 2:1 fumarate salt was found to be in good agreement with the calculated pattern from the single crystal (NP-2162-169-1, which was grown from NP-2162-163-3). The peak lists for the calculated and experimental XRPD pattern of the single crystal of the 2:1 fumarate salt is shown in Table 28 and 29. 
     
       
         
           
               
             
               
                 TABLE 28 
               
             
            
               
                   
               
               
                 Peak list of NP-2162-163-3 
               
               
                 (Calculated from SCXRD). 
               
            
           
           
               
               
               
            
               
                 Angle 
                 Intensity % 
                 d value 
               
               
                 2-Theta °  
                 % 
                 Angstrom 
               
               
                   
               
            
           
           
               
               
               
            
               
                 17.47 
                 1.8 
                 5.071 
               
               
                 19.26 
                 6.8 
                 4.604 
               
               
                 19.71 
                 3.3 
                 4.502 
               
               
                 20.67 
                 5.3 
                 4.294 
               
               
                 22.90 
                 9.3 
                 3.880 
               
               
                 25.91 
                 2.5 
                 3.436 
               
               
                 26.78 
                 100 
                 3.327 
               
               
                 27.51 
                 3.2 
                 3.240 
               
               
                 28.73 
                 2.7 
                 3.105 
               
               
                 29.12 
                 1.8 
                 3.065 
               
               
                 31.16 
                 2.5 
                 2.868 
               
               
                 33.04 
                 1.7 
                 2.709 
               
               
                 33.98 
                 3.5 
                 2.636 
               
               
                 35.27 
                 3.1 
                 2.542 
               
               
                 39.05 
                 2.7 
                 2.305 
               
               
                 23.82 
                 2.9 
                 3.732 
               
               
                 24.09 
                 3.2 
                 3.691 
               
               
                 20.97 
                 5.7 
                 4.234 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 29 
               
             
            
               
                   
               
               
                 Peak list of 2162-64-1. 
               
            
           
           
               
               
               
            
               
                 Angle 
                 Intensity % 
                 d value 
               
               
                 2-Theta °  
                 % 
                 Angstrom 
               
               
                   
               
            
           
           
               
               
               
            
               
                 11.73 
                 12.1 
                 7.537 
               
               
                 13.92 
                 13.8 
                 6.359 
               
               
                 17.38 
                 15.2 
                 5.100 
               
               
                 19.15 
                 24.7 
                 4.630 
               
               
                 19.58 
                 45.7 
                 4.530 
               
               
                 19.99 
                 18.7 
                 4.439 
               
               
                 20.53 
                 64.9 
                 4.323 
               
               
                 20.97 
                 17 
                 4.233 
               
               
                 22.83 
                 31.6 
                 3.892 
               
               
                 23.69 
                 13.4 
                 3.753 
               
               
                 25.53 
                 13.5 
                 3.487 
               
               
                 26.69 
                 100 
                 3.338 
               
               
                 27.48 
                 12.1 
                 3.243 
               
               
                 28.64 
                 26.4 
                 3.115 
               
               
                 29.02 
                 11.8 
                 3.074 
               
               
                 31.07 
                 18.1 
                 2.876 
               
               
                 35.25 
                 13 
                 2.544 
               
               
                 38.94 
                 14.8 
                 2.311 
               
               
                   
               
            
           
         
       
     
     Example 20. Capsule Fill Evaluation of 2:1 Succinate Salt 
     The purpose of the following experiments was to determine the maximum allowable fill weight of β-Guanidiopropionic Acid into size 0 capsules and resulting disintegration behavior. Jet milling and roller compaction feasibility were also performed to determine the effect on resulting net capsule fill weight. The free acid and the 2:1 succinate salt form of β-GPA were both evaluated. 
     The two β-GPA samples evaluated are given in Table 30. 
     
       
         
           
               
             
               
                 TABLE 30 
               
             
            
               
                   
               
               
                 Samples evaluated. 
               
            
           
           
               
               
               
            
               
                   
                 Description From Label 
                 Lot 
               
               
                   
                   
               
               
                   
                 3-Guanidinopropionic 
                 Batch #10 
               
               
                   
                 Acid 
                   
               
               
                   
                 β-Guanidinopropionic 
                 ELS-104-76-25 
               
               
                   
                 Acid Succinate Salt 
               
               
                   
                   
               
            
           
         
       
     
     Hand Fill Assessment 
     Both lots of material were hand filled using a Torpac size 0 capsule loader into size 0 Swedish orange V-cap capsules. Two hand filling methods were evaluated. Free flow capsules were prepared by gravity filling, without the use of tamping, until the bottom section of the size 0 capsule was filled to the brim. Excess material was gently scraped using a spatula. Tamp filled capsules were prepared by constantly filling and then tamping the material until reaching the brim of the size 0 capsule bottom. A total of N=5 capsules were filled for each lot for each method. The average net fill weight results are given below in Table 31. 
     
       
         
           
               
             
               
                 TABLE 31 
               
             
            
               
                   
               
               
                 Net fill weight of size 0 capsule filled with API 
               
            
           
           
               
               
               
               
            
               
                   
                   
                 Fill  
                 Average Net  
               
               
                 API 
                 Lot Number 
                 Method 
                 Weight (mg) 
               
               
                   
               
               
                 3-Guanidinopropionic 
                 1366-1-2-A 
                 Free Flow 
                 207.0 
               
               
                 Acid 
                 1366-1-2-B 
                 Tamp 
                 471.6 
               
               
                 β-Guanidinopropionic 
                 1366-1-7-A 
                 Free Flow 
                 320.2 
               
               
                 Acid Succinate Salt 
                 1366-1-7-B 
                 Tamp 
                 451.3 
               
               
                   
               
            
           
         
       
     
     As expected capsules filled by the tamp method had a significantly higher fill amount compared those which were free flow filled. However, it should be noted that these methods of filling will not be represent of performance on an automated encapsulation machine. Based on the data it can be determined that the Succinate Salt form allowed for better free flow filling into capsules allowing for 113 mg more material to be filled into a size 0 capsule. Tamp filling however both forms performed relatively the same. 
     Roller Compaction Feasibility 
     Roller compaction feasibility was performed by producing slugs using a single station hand press then carefully hand milling those slugs so that all granules were small enough to pass through a size US 18 mesh. These granules were then filled into size 0 capsules by both the free flow and tamp method. A total of N=5 capsules were filled for each lot for each method. The average net fill weight results are given below in Error! Reference source not found.2. 
     
       
         
           
               
             
               
                 TABLE 32 
               
             
            
               
                   
               
               
                 Net fill weight of size 0 capsules filled with roller compacted API 
               
            
           
           
               
               
               
               
            
               
                   
                   
                 Fill  
                 Average Net  
               
               
                 API 
                 Lot Number 
                 Method 
                 Weight (mg) 
               
               
                   
               
               
                 3-Guanidinopropionic 
                 1366-1-7-A 
                 Free Flow 
                 303.6 
               
               
                 Acid 
                 1366-1-7-B 
                 Tamp 
                 568.2 
               
               
                 β-Guanidinopropionic 
                 1366-1-14-A 
                 Free Flow 
                 335.4 
               
               
                 Acid Succinate Salt 
                 1366-1-14-B 
                 Tamp 
                 574.6 
               
               
                   
               
            
           
         
       
     
     While it does appear from the data set that roller compaction of the free acid API does provide a benefit to capsule filling it should be noted that slugs produced in this fashion had an extremely low tensile strength. Slugs produced using up to 2000 psi (36 mPa, 9 kN) worth of force were so soft that a proper hardness value was not able to be obtained when tested using a tablet hardness tester. The calculated solid fraction for these slugs was 74%. The historical range for solid fraction of acceptable ribbons for roller compaction is between 50% to 80%. Slugs were milled by hand as any other method would have been too energy intensive and most likely cause any granules produced to be destroyed. That being said maximum capsule fill weight increased by roughly 100 mg for both free flow and tamp filled capsules. 
     The same issue was not seen when compressing the succinate salt form of β-GPA. Slugs produced around 1500 PSI produced slugs hard enough to be tested for hardness. The resulting slug parameters can be seen in Table 33. 
     
       
         
           
               
             
               
                 TABLE 33 
               
             
            
               
                   
               
               
                 Slug Parameters for β-Guanidinopropionic Acid Succinate Salt 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                 Tablet  
                 Tablet 
                 Tablet 
                 Compression 
                 Compression 
                 Tensile 
                 Calculated 
               
               
                   
                 Weight 
                 Thickness 
                 Hardness 
                 Force 
                 Stress 
                 Strength 
                 Solid  
               
               
                   
                 (mg) 
                 (mm) 
                 (kp) 
                 PSI 
                 (MPa) 
                 (MPa) 
                 Fraction 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                 1505.7 
                 4.77 
                 6.8 
                 2000 
                 36 
                 0.50 
                 0.85 
               
               
                   
                 1521.4 
                 5.2 
                 4.4 
                 1500 
                 27 
                 0.30 
                 0.79 
               
               
                   
                 1545.2 
                 5.28 
                 4.3 
                 1500 
                 27 
                 0.29 
                 0.79 
               
               
                   
                 1493.6 
                 5.09 
                 5.1 
                 1500 
                 27 
                 0.35 
                 0.79 
               
               
                   
                 1502.1 
                 5.12 
                 3.7 
                 1500 
                 27 
                 0.25 
                 0.79 
               
               
                 Average 
                 1513.60 
                 5.09 
                 4.86 
                 1600.00 
                 28.67 
                 0.34 
                 0.80 
               
               
                 Std 
                 20.34 
                 0.19 
                 1.19 
                 223.61 
                 4.01 
                 0.10 
                 0.03 
               
               
                 RSD 
                 1.34 
                 3.82 
                 24.55 
                 13.98 
                 13.98 
                 28.89 
                 3.41 
               
               
                   
               
            
           
         
       
     
     However, it should be noted that slugs produced on the single station were extremely difficult to remove. This high ejection force was due to the material sticking and smearing along the die wall. The free flow maximum capsule fill weight for the salt form remained relatively the same after roller compaction however the tamp filled maximum capsule fill weight increased by 120 mg. 
     Jet Milling Feasibility 
     Jet Milling feasibility was performed using a Jet-O-Mizer 2 inch jet mill. Roughly 5 grams of material was milled for each form of β-GPA. The parameters used and the resulting yields can be seen in Table 34. 
     
       
         
           
               
             
               
                 TABLE 34 
               
               
                   
               
               
                 Jet Mill Feasibility Parameters 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 Lot Number 
                 1366-1-11 
                 1366-1-12 
               
               
                 API 
                 β-Guanidinopropionic 
                 3-Guanidinopropionic 
               
               
                   
                 Acid Succinate Salt 
                 Acid 
               
               
                 Supply Air 
                 140 
                 140 
               
               
                 Grinding Nozzle 
                 100 
                 100 
               
               
                 Pressure 
                   
                   
               
               
                 Pusher Nozle  
                 80 
                 80 
               
               
                 Pressure 
                   
                   
               
               
                 Vibratory Feeder 
                 3 
                 3 
               
               
                 Setting 
                   
                   
               
               
                 Amount before  
                 8.1477 
                 6.6893 
               
               
                 milling (g) 
                   
                   
               
               
                 Amount after  
                 5.2610 
                 4.4165 
               
               
                 milling (g) 
                   
                   
               
               
                 Yield (%) 
                 64.6 
                 66.0 
               
               
                   
               
            
           
         
       
     
     The milled API was hand filled into size 0 capsules using the free flow and tamp filled method. Resulting net average capsule fill weights are given in Table 35. 
     
       
         
           
               
             
               
                 TABLE 35 
               
             
            
               
                   
               
               
                 Net fill weight of size 0 capsules filled with et milled API 
               
            
           
           
               
               
               
               
            
               
                   
                   
                 Fill  
                 Average Net  
               
               
                 API 
                 Lot Number 
                 Method 
                 Weight (mg) 
               
               
                   
               
               
                 3-Guanidinopropionic 
                 1366-1-13-A 
                 Free Flow 
                 119.2 
               
               
                 Acid 
                 1366-1-13-B 
                 Tamp 
                 356.8 
               
               
                 β-Guanidinopropionic 
                 1366-1-14-A 
                 Free Flow 
                 118.0 
               
               
                 Acid Succinate Salt 
                 1366-1-14-B 
                 Tamp 
                 426.4 
               
               
                   
               
            
           
         
       
     
     Jet milling of the API caused a decrease in the maximum fill of size 0 capsule. This is most likely because the jet milling process can produce powders that are often highly cohesive and have poor flowability properties, as well as lower bulk density. 
     DSC and XRPD were performed on both API&#39;s before and after jet milling in order to determine if any change in material structure occurred due to the milling process. 
     Looking at the traces there was no change in the DSC trace for either API. There is a degradation peak present on the DSC for the non-salt form before jet milling which does not appear to on the post jet milling trace, but this is most likely degradation. The overlay DSC traces can be seen in  FIG. 44  and  FIG. 45 . 
     The XRPD traces for each API also remained unchanged. The intensities of the peaks do differ between pre and post jet milling, however this most likely due to preferred orientation and the peaks are still consistent with one another. The PXRD traces can be seen in  FIGS. 46 and 47 . 
     Disintegration Evaluation 
     Filled capsules from each feasibility study were tested for disintegration in water. Water was brought to a temperature of 37±3° C. before beginning testing. Results of these disintegration trials are giving below in Table 36. 
     
       
         
           
               
             
               
                 TABLE 36 
               
             
            
               
                   
               
               
                 Disintegration Results 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                   
                   
                 Disintegration 
                 Initial 
                 Final 
                   
               
               
                   
                   
                   
                 Time 
                 Temp 
                 Temp 
                   
               
               
                 Lot 
                 Description 
                 API 
                 (min:sec) 
                 (° C.) 
                 (° C.) 
                 Observation 
               
               
                   
               
               
                 1366-1-2-A 
                 Free Flow 
                 3-Guanidinopropionic 
                 03:44 
                 36.9 
                 37.0 
                 All solids dissolved 
               
               
                   
                   
                 Acid 
                   
                   
                   
                 soon as capsule 
               
               
                   
                   
                   
                   
                   
                   
                 breached 
               
               
                 1366-1-2-B 
                 Tamp Fill 
                 3-Guanidinopropionic 
                 03:44 
                 36.9 
                 37.0 
                 All solids dissolved 
               
               
                   
                   
                 Acid 
                   
                   
                   
                 soon as capsule 
               
               
                   
                   
                   
                   
                   
                   
                 breached 
               
               
                 1366-1-5-A 
                 RC, Free 
                 3-Guanidinopropionic 
                 03:44 
                 36.9 
                 37.0 
                 All solids dissolved 
               
               
                   
                 Fill 
                 Acid 
                   
                   
                   
                 soon as capsule 
               
               
                   
                   
                   
                   
                   
                   
                 breached 
               
               
                 1366-1-5-B 
                 RC, Tamp 
                 3-Guanidinopropionic 
                 04:32 
                 36.9 
                 37.0 
                 Some Small 
               
               
                   
                 Fill 
                 Acid 
                   
                   
                   
                 Granules observed 
               
               
                   
                   
                   
                   
                   
                   
                 during capsule 
               
               
                   
                   
                   
                   
                   
                   
                 breaking 
               
               
                 1366-1-7-A 
                 Free Flow 
                 β-Guanidinopropionic 
                 03:59 
                 38.1 
                 38.0 
                 All solids dissolved 
               
               
                   
                   
                 Acid Succinate Salt 
                   
                   
                   
                 soon as capsule 
               
               
                   
                   
                   
                   
                   
                   
                 breached 
               
               
                 1366-1-7-B 
                 Tamp Fill 
                 β-Guanidinopropionic 
                 04:17 
                 38.1 
                 38.0 
                 All solids dissolved 
               
               
                   
                   
                 Acid Succinate Salt 
                   
                   
                   
                 soon as capsule 
               
               
                   
                   
                   
                   
                   
                   
                 breached 
               
               
                 1366-1-13-A 
                 JM, Free 
                 3-Guanidinopropionic 
                 05:27 
                 38.1 
                 38.0 
                 All solids dissolved 
               
               
                   
                 Flow 
                 Acid 
                   
                   
                   
                 soon as capsule 
               
               
                   
                   
                   
                   
                   
                   
                 breached 
               
               
                 1366-1-13-B 
                 JM, Tamp 
                 3-Guanidinopropionic 
                 05:27 
                 38.1 
                 38.0 
                 All solids dissolved 
               
               
                   
                 Fill 
                 Acid 
                   
                   
                   
                 soon as capsule 
               
               
                   
                   
                   
                   
                   
                   
                 breached 
               
               
                 1366-1-14-A 
                 JM, Free 
                 β-Guanidinopropionic 
                 02:39 
                 36.9 
                 37.1 
                 All solids dissolved 
               
               
                   
                 Flow 
                 Acid Succinate Salt 
                   
                   
                   
                 soon as capsule 
               
               
                   
                   
                   
                   
                   
                   
                 breached 
               
               
                 1366-1-14-B  
                 JM, Tamp 
                 β-Guanidinopropionic 
                 03:09 
                 36.9 
                 37.1 
                 All solids dissolved 
               
               
                   
                 Fill 
                 Acid Succinate Salt 
                   
                   
                   
                 soon as capsule 
               
               
                   
                   
                   
                   
                   
                   
                 breached 
               
               
                 1366-1-15-A 
                 RC, Free 
                 β-Guanidinopropionic 
                 02:53 
                 36.9 
                 37.1 
                 All solids dissolved 
               
               
                   
                 Flow 
                 Acid Succinate Salt 
                   
                   
                   
                 soon as capsule 
               
               
                   
                   
                   
                   
                   
                   
                 breached 
               
               
                 1366-1-15-B 
                 RC, Tamp 
                 β-Guanidinopropionic 
                 02:58 
                 36.9 
                 37.1 
                 Some Small 
               
               
                   
                 Fill 
                 Acid Succinate Salt 
                   
                   
                   
                 Granules observed 
               
               
                   
                   
                   
                   
                   
                   
                 during capsule 
               
               
                   
                   
                   
                   
                   
                   
                 breaking 
               
               
                   
               
               
                 RC = Roller Compacted granules, 
               
               
                 JM = Jet milled material 
               
            
           
         
       
     
     There were not significant differences in the disintegration times of the capsules produced. The only observations made were that some of the capsules which contained roller compacted material did have small granules escape after the capsule breaching. These granules dissolved within 30 seconds of being released in the disintegration media. 
     Compression Profile Evaluation 
     Compression profiling was also performed on both the free base and the salt form of the API. A standard formulation containing plastic diluent, brittle diluent, disintegrant and lubricant was evaluated at a loading of 25% and 50% API. The diluent level was adjusted accordingly, but the ratio of plastic to brittle filler was set a 1:1. It was decided to use a representative tablet formulation to perform compression profiling to mitigate the cohesion and sticking issues seen in the free base and the salt form during the roller compaction feasibility evaluation. Table 37 details the formulation compositions tested. 
     
       
         
           
               
             
               
                 TABLE 37 
               
             
            
               
                   
               
               
                 Compression Profiling Formulations 
               
            
           
           
               
               
               
               
               
               
            
               
                   
                   
                 1366- 
                 1366- 
                 1366- 
                 1366- 
               
               
                   
                 De- 
                 1-18 
                 1-19 
                 1-20 
                 1-20 
               
               
                 Component 
                 scription 
                 % (w/w) 
                 % (w/w) 
                 % (w/w) 
                 % (w/w) 
               
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 3-GPA 
                 API 
                 50.0 
                 25.0 
                   
                   
               
               
                 β-GPA Salt 
                 API 
                   
                   
                 50.0 
                 25.0 
               
               
                 Avicel PH200 
                 Plastic  
                 22.0 
                 34.5 
                 22.0 
                 34.5 
               
               
                   
                 Diluent 
                   
                   
                   
                   
               
               
                 Lactose 316 
                 Brittle  
                 22.0 
                 34.5 
                 22.0 
                 34.5 
               
               
                   
                 Diluent 
                   
                   
                   
                   
               
               
                 Croscarmellose 
                 Dis- 
                 5.0 
                 5.0 
                 5.0 
                 5.0 
               
               
                 Sodium 
                 integrant 
                   
                   
                   
                   
               
               
                 Mag Stearate 
                 Lubricant 
                 1.0 
                 1.0 
                 1.0 
                 1.0 
               
               
                   
               
            
           
         
       
     
     These blends were then compressed into 100 mg compacts using 0.25-inch flat faced tooling at increasing compaction pressures. A total of N=3 compacts were produced at each compaction pressure and were measured for weight, thickness and hardness. The compression stresses used were calculated by dividing the force applied to the compact by the surface area of the 0.25 in flat faced tooling. The tensile strength of the compacts was calculated using the equations derived for flat faced tablets. For each formulation, a tabletability (tensile strength vs. compression pressure) was generated. For the purposes of this study the tabletability profile was examined to determine the compaction pressure required in order to produce a tablet of acceptable tensile strength. Historically a tablet with a tensile strength of 2.0 Mpa is sufficient to both withstand friability and to not impact disintegration and dissolution. 
       FIG. 48  shows the tabletability profile for the free base form of β-GPA. It is observed that the 50% API loading formulation seems to be incapable of reaching a tablet with 2.0 Mpa even at upwards of 400 mPa of compression force. As the API loading is reduced to 25% API the tabletability of the formulation increases. It would still require roughly 235 Mpa of compression stress to produce a tablet of 2.0 Mpa of strength at the 25% loading. 
       FIG. 49  shows the tabletability profile for the β-GPA salt form. Like the free base, tabletability improves with additional diluent in the formulation when moving from a 50% to a 25% API loading. For the 50% API formulation, an estimated 230 Mpa of compaction pressure or a compaction force of 34.8 kN would be required to produce a tablet of 2.0 Mpa tensile strength. At 25% API loading the compaction pressure required is reduced to 150 Mpa or a compaction force of 22.7 kN. This tablet would provide a 250 mg dose of the API salt form. During compaction, there were no signs of “sticking” to the die wall during ejection. 
     Other Embodiments 
     While the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modifications and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure that come within known or customary practice within the art to which the invention pertains and may be applied to the essential features herein before set forth.