Abstract:
The present invention provides novel anhydrous polymorph forms of [(2R,3S,4R,5R)-5-(6-(cyclopentylamino)-9H-purin-9-yl)-3,4-dihydroxytetrahydrofuran-2-yl)]methyl nitrate (compound A), a selective adenosine A 1  receptor agonist with a number of therapeutic uses including the treatment of elevated intra-ocular pressure. Also provided are methods for the preparation of the anhydrous polymorphic forms of compound A, pharmaceutical compositions and methods of treatment.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 13/750,389, filed on Jan. 25, 2013, which issued as U.S. Pat. No. 9,278,991 on Mar. 8, 2016, which claims priority to, and the benefit of, U.S. Provisional Application No. 61/591,037, filed on Jan. 26, 2012. The entire contents of the aforementioned application and any patents, patent applications, and references cited throughout this specification are herein incorporated by reference in their entireties. 
    
    
     FIELD OF THE INVENTION 
     The present invention provides novel anhydrous polymorph forms of [2R,3S,4R,5R)-5-(6-(cyclopentylamino)-9H-purin-9-yl)-3,4-dihydroxytetrahydrofuran-2-yl)]methyl nitrate (Compound A) and to processes of preparation thereof. 
     BACKGROUND OF THE INVENTION 
     Compound A is represented by the following structure 
     
       
                 
         
             
             
         
      
         
         
           
             [(2R,3S,4R,5R)-5-(6-(cyclopentylamino)-9H-purin-9-yl)-3,4-dihydroxytetrahydrofuran-2-yl)]methyl nitrate, 
           
         
       
    
     Compound A is a selective adenosine A 1  receptor agonist and is of particular use in the treatment of elevated intra-ocular pressure as described in PCT/US2010/033112 (published as WO2010/127210). 
     Compound A can be prepared using the procedures described in U.S. Pat. No. 7,423,144, US 20090062314, and WO2010/127210 all of which are herein incorporated by reference in their entirety. 
     Many pharmaceutical solids can exist in different physical forms. Polymorphism can be characterized as the ability of a drug substance to exist in two or more crystalline phases that have different arrangements and/or conformations of the molecules in the crystal lattice. 
     Polymorphs of a pharmaceutical solid can have different physical and solid state chemical properties. The most stable polymorphic form of a drug substance is often used because it has the lowest potential for conversion from one polymorphic form to another. 
     A particular crystalline form of a compound can have physical properties that differ from those of other polymorphic forms and such properties can influence the physico-chemical and pharmaceutical processing of the compound, particularly when the compound is prepared or used on a commercial scale. Such differences may alter the mechanical handling properties of the compound, such as dispersion in a blend of solid formulation excipients or within a suspension formulation. Polymorphs are also known in some cases to have different chemical stability profiles and different solubility of the solid material. As a result of these potential polymorph-specific physiochemical differences, the discovery of new polymorphic forms provides a new opportunity to improve the manufacturing or characteristics of a pharmaceutical end product. 
     Further, new polymorphic forms of a drug substance can display different melting point, hygroscopicity, stability, solubility and/or dissolution rate, crystallinity, crystal properties, and formulation handling characteristics, which are among the numerous properties that need to be considered in preparing medicament that can be effectively administered, they can materially impact the quality of a pharmaceutical product. Furthermore, regulatory agencies require a definitive knowledge, characterization and control of the polymorphic form of the active component in pharmaceutical dosage forms if it is in the solid state. 
     Compound A is under development by the Applicants for reducing intraocular pressure. The Applicants have found a number of polymorphs of Compound A that are useful for controlling certain desirable formulation properties. In particular two anhydrous forms have been identified, isolated and characterized. 
     SUMMARY OF INVENTION 
     Provided herein are anhydrous polymorphs of Compound A, and methods of preparation thereof. 
     Thus, in a first aspect there is provided an isolated anhydrous polymorph A1 of Compound A having the following crystal data, 
     C 15 H 20 N 6 0 6 ; 
     Mr=380.37; 
     Monoclinic crystal system; 
     P2 1  space group; 
     a=5.546(2) Å; 
     b=7.107(2) Å; 
     c=21.929(9) Å; 
     V=858.8(5) Å 3 , and 
     Z=2. 
     In another aspect there is provided an isolated polymorph A1 of Compound A having substantially equivalent peaks at a reflection angle 2-theta as shown in Table 3. 
     In one embodiment there is provided an isolated polymorph of form A1 as defined above that is at least about 75% free of other polymorphic forms. 
     In one embodiment there is provided an isolated polymorph as defined above that is at least about 80% free of other polymorphic forms. 
     In one embodiment there is provided an isolated polymorph as defined above that is at least about 90% free of other polymorphic forms. 
     In one embodiment there is provided an isolated polymorph as defined above that is at least about 95% free of other polymorphic forms. 
     In one embodiment there is provided an isolated polymorph as defined above that is at least about 99% free of other polymorphic forms. 
     In one embodiment there is provided an isolated polymorph as defined above that is 100% free of other forms. 
     In another aspect there is provided a method of obtaining the polymorph A1, the method comprising the steps of taking Compound A and recrystallizing from ethanol. 
     In another aspect there is provided a method of obtaining the polymorph A1, the method comprising the steps of taking Compound A and recrystallizing from isopropanol, ethyl acetate, or isopropyl acetate. 
     In another aspect there is provided a method of obtaining the polymorph A1, the method comprising the steps of taking Compound A and recrystallizing from 1,4 dioxane, 2-methoxy ethanol, 3-methyl-2-butanone, methylethyl ketone, or 1,2-dimethoxyethane. 
     In another aspect there is provided a pharmaceutical composition comprising polymorph A1 as defined above and further comprising one or more pharmaceutically acceptable ingredients selected from the group consisting of carriers, excipients, diluents, additives, fillers, surfactants, binders, antimicrobial preservatives, viscosity enhancing agents, and buffers. 
     In one embodiment the pharmaceutical composition comprising polymorph A1 defined above is formulated for ophthalmic administration. 
     In a further aspect, there is also provided a method of treating a subject in need of a selective adenosine A 1  agonist, the method comprising administering to a subject in need thereof a therapeutically effective amount of the polymorph A1 defined above. 
     In a further aspect, there is also provided a method of reducing intraocular pressure in a subject, the method comprising topically administering to an eye of a subject in need thereof a therapeutically effective amount of the polymorph A1 defined above. 
     Thus, in another aspect there is provided a polymorph A2 of Compound A having the following crystal data, 
     C 15 H 20 N 6 0 6 ; 
     Mr=380.37; 
     Orthorhombic crystal system; 
     P2 1 2 1 2 1  space group; 
     a=5.51796(17) Å; 
     b=7.14615(29) Å; 
     c=42.9738(29) Å and 
     V=1694.55(14) Å 3 . 
     Thus, in another aspect there is provided a polymorph A2 of Compound A having substantially equivalent peaks at a reflection angle 2-theta as shown in Table 5. 
     In one embodiment there is provided an isolated polymorph as defined above that is at least about 75% free of other forms. 
     In one embodiment there is provided an isolated polymorph as defined above that is at least about 80% free of other forms. 
     In one embodiment there is provided an isolated polymorph as defined above that is at least about 90% free of other forms. 
     In one embodiment there is provided an isolated polymorph as defined above that is at least about 95% free of other forms. 
     In one embodiment there is provided an isolated polymorph as defined above that is at least about 99% free of other forms. 
     In one embodiment there is provided an isolated polymorph as defined above that is 100% free of other forms. 
     In another aspect there is provided a method of obtaining the polymorph A2, the method comprising the steps of taking Compound A in a liquid vehicle and heating up to about 40 degrees for at least 9 hours. 
     In one embodiment the Compound A is micronized and then added to an aqueous liquid vehicle. In one embodiment Compound A is micronized into particles with sizes less than 50 microns. 
     In one embodiment the method includes the step of heating to about 40 degrees C. for 15 hours. 
     In one embodiment the liquid vehicle is adapted to provide an aqueous suspension of Compound A. In another embodiment the liquid vehicle includes a surfactant and a preservative. In one embodiment the surfactant is selected from polysorbate 80, polysorbate 60, polysorbate 40, polysorbate 20, polyoxyl 40 stearate, poloxamers, tyloxapol, POE 35 and castor oil. In one embodiment the preservative in selected from a quaternary ammonium salt, benzalkonium chloride, cetrimide, chlorobutanol, sorbic acid and boric acid. 
     In another aspect there is provided a pharmaceutical composition comprising polymorph A2 as defined above and further comprising one or more pharmaceutically acceptable ingredients selected from the group consisting of carriers, excipients, diluents, additives, fillers, surfactants, binders, antimicrobial preservatives, viscosity enhancing agents, and buffers. 
     In one embodiment the pharmaceutical composition comprising polymorph A2 defined above is formulated for ophthalmic administration. 
     In a further aspect, there is also provided a method of treating a subject in need of a selective adenosine A 1  agonist, the method comprising administering to a subject in need thereof a therapeutically effective amount of the polymorph A2 defined above. 
     In a further aspect, there is also provided a method of reducing intraocular pressure in a subject, the method comprising topically administering to an eye of a subject in need thereof a therapeutically effective amount of the polymorph A2 defined above. 
     The foregoing brief summary broadly describes the features and technical advantages of certain embodiments of the present invention. Further technical advantages will be described in the detailed description of the invention that follows. Novel features which are believed to be characteristic of the invention will be better understood from the detailed description of the invention when considered in connection with any accompanying figures and examples. However, the figures and examples provided herein are intended to help illustrate the invention or assist with developing an understanding of the invention, and are not intended to be definitions of the invention&#39;s scope. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1 : shows the molecular structure and atom numbering scheme for Compound A—Form A1. 
         FIG. 2 : shows the packing arrangement and H-bonds for Compound A—Form A1 crystals. 
         FIG. 3 : shows the molecular structure and atom numbering scheme for Compound A—Form A2 
         FIG. 4 : shows the packing arrangement and H-bonds for Compound A—Form A2 crystals. 
         FIG. 5 : shows an overlay in the x-ray powder spectra observed for the forms of Compound A described herein. The lower gray line represents the A1 form and the upper black line represents the form A2. 
         FIG. 6 : shows the superposition of molecules of Form A1 (black) and Form A2 (grey) 
         FIG. 7 : shows the XRPD data plot of conversion of polymorph form A1 to polymorph form A2 over time at 40 degrees C. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Embodiments of the present invention provide anhydrous polymorphs of Compound A. 
     Definitions 
     Some chemical structures herein are depicted using bold and dashed lines to represent chemical bonds. These bold and dashed lines depict absolute stereochemistry. A bold line indicates that a substituent is above the plane of the carbon atom to which it is attached and a dashed line indicates that a substituent is below the plane of the carbon atom to which it is attached. 
     The term “effective amount” as used herein refers to an amount of a selective adenosine A1 agonist that is effective for: (i) treating or preventing elevated IOP; or (ii) reducing IOP in a human. 
     The term “subject” is intended to include organisms, e.g., prokaryotes and eukaryotes, which are capable of suffering from or afflicted with a disease, disorder or condition associated with elevated IOP. Examples of subjects include mammals, e.g., humans, dogs, cows, horses, pigs, sheep, goats, cats, mice, rabbits, rats, and transgenic non-human animals. In certain embodiments, the subject is a human, e.g., a human suffering from, at risk of suffering from, or potentially capable of suffering from an increase in IOP. In another embodiment, the subject is a cell. 
     The term “treat,” “treated,” “treating” or “treatment” includes the diminishment or alleviation of at least one symptom associated or caused by the state, disorder or disease being treated. In certain embodiments, the treatment comprises the induction of elevated IOP, followed by the activation of the compound of the invention, which would in turn diminish or alleviate at least one symptom associated or caused by the elevated IOP. For example, treatment can be diminishment of one or several symptoms of a disorder or complete eradication of a disorder. 
     The term “about” or “substantially” usually means within 20%, more preferably within 10%, and most preferably still within 5% of a given value or range. 
     Methods of Preparation and Studies 
     Synthesis of Compound A 
     The following Scheme1 shows the reaction scheme in the preparation of Compound A. The preparation of Compound A is described in detail. 
     The quantities detailed are calculated for a production batch of approximately 40 gms of Compound A. The production described can be scaled up. 
     Step 1: 1 Liter of ethanol was charged into a reactor and stirred rapidly. 0.3 kg of 6-chloroadenosine and 0.267 kg of cyclopentylamine were added to the ethanol in the reactor. The reactor was heated to reflux for 2 hr, then cooled to 8 degrees C. and kept under these conditions for 12 hours. The crystallized material was filtered from the mother liquid and the solid cake was washed with 0.33 L of ethanol to produced a wet cake. The wet cake was dried to obtain N6-cyclopentyladenosine (0.249 kg). 
     Step 2: Dimethoxypropane was used to protect the 2′ and 3′ hydroxyls on the sugar unit. 3.7 liters of acetone was charged into the reactor and was stirred rapidly. 0.249 kg of N6-cyclopentyladenosine; 0.386 kg of dimethoxypropane and 0.148 kg of p-toluenesulfonic acid were added to the acetone (3.7 L) in the reactor. The reactor was heated to 40 degrees C. for 1.5 hours. The solvents were then removed by distillation under vacuum at 40 degrees C. to prepare a dry crude material. 3.1 L of ethyl acetate were then added to the dry crude material obtained. The solution was then cooled to 6 degrees C. and 0.5N NaOH solution was added by dripping until a pH of 8 was reached. This equated to approximately 1.55 L of NaOH solution. After the phase separation was complete, 0.78 L of saturated sodium chloride 20% solution was added to the organic phase. 0.78 L of saturation sodium chloride 20% solution was added again. The two phases were stirred for 30 minutes. The organic phase that was ethyl acetate based was separated and dried with 0.157 kg of sodium sulfate and washed with 1 L of ethyl acetate. The solution was filtered and evaporated to an oil under vacuum at 55 degrees C. To the remaining oil 1.2 L of hexane and 0.3 L of ethyl acetate were added. The reaction mixture was heated to 55 degrees C. for 3 hours and then the solution was cooled to 5 degrees C. and maintained at this temperature for 12 hours. The solids were filtered and the resulting cake was washed with a 0.625 L of ethyl acetate:hexane (1:4) solution. After drying the solid 140 g of 2′,3′-isopropylidene-N 6 -cyclopentyl adenosine was obtained. 
     Step 3: Nitration of the 5′ position of 2′,3′-isopropylidene-N 6 -cyclopentyl adenosine obtained in Step 2 was carried out with a nitric acid acetic anhydride mixture. 0.127 L of dichloromethane was charged into the reactor and stirred rapidly. 140 g of 2′,3′-isopropylidene-N 6 -cyclopentyl adenosine was added and the reaction solution was cooled to −20 degrees C. 0.547 L of a solution composed of 0.127 L nitric acid 65% in 0.420 L of acetic anhydride was added at a rate that kept the reaction mixture below −15 degrees C.—the temperature range of between −23 to −18 degrees C. has been found to be the preferred target range. If the temperature increases, then impurities were found to be generated. The addition of the acid mixture took about 0.5 hr. The mixture was stirred for 20 minutes and then quenched into 0.35 L of cold saturated sodium bicarbonate solution. The pH was corrected to 7 by the addition of solid sodium bicarbonate to the aqueous later. The organic phase was separated and the aqueous layer extracted with 0.4 L of dichloromethane. The organic phases were combined and washed with 0.6 L of saturated sodium chloride solution. The organic phase containing 2′,3′-isopropylidene-N 6 -cyclopentyladenosine-5′-nitrate was then separated for use in Step 4 below. 
     Step 4: Because of its lability the protected 2′,3′-isopropylidene-N 6 -cyclopentyladenosine-5′-nitrate was hydrolyzed directly without purification. The solution from Step 3 was evaporated at 20 degrees C. under vacuum to an oil. The oil was cooled to less than 2 degrees C. 1.95 L of trifluoroacetic acid:water (3:1) solution was added. The reaction mixture was stirred for 0.5 hours and allowed to warm to room temperature while being stirred. After that, the sodium bicarbonate solution was prepared and cooled to less than 10 degrees C. The sodium bicarbonate solution was added to the reaction mixture to quench the reaction. The ethyl acetate was added to the reaction vessel and the pH was adjusted and the organic layer was worked up and dried with sodium sulfate. The resulting product solution was then dried several times with magnesium sulfate and the material stripper to form crude Compound A. 
     The crude compound A was then recrystallized from ethanol. The crude compound A material was dissolved in ethanol then concentrated to half volume to crystallize for 36 hours. After that the resulting product was isolated by filtration to provide Compound A.  1 H-NMR (DMSO-d 6 ): δ 1.49-1.58 (m, 4H), 1.66-1.72 (m, 2H), 1.89-1.94 (m, 2H), 4.12-4.17 (m, 1H), 4.28-4.33 (m, 1H), 4.48 (bs, 1H), 4.65-4.87 (m, 3H), 5.5 (d, J=5.1 Hz, 1H), 5.63 (d, J=5.7 Hz, 1H), 5.91 (d, J=5.1 Hz, 1H), 7.75 (d, J=7.5 Hz, 1H), 8.17 (bs, 1H), 8.30 (s, 1H); MS (ES + ): m/z 381.35 (M+1); Anal. Calculated for C 15 H 20 N 6 O 6 : C, 47.37; H, 5.30; N, 22.10. Found: C, 47.49; H, 5.12; N, 21.96. 
                                                          
Preparation of Polymorphs A1 and A2
 
     
       
                 
         
             
             
         
      
     
     During the preparation of ophthalmic solutions of Compound A, variability was seen in particle growth size and stability. Because of the variability, efforts have been made to establish if one or more polymorphs could be isolated and purified in order to overcome the variability in particle size growth and stability. 
     Crystallization Study: 
     The Compound A material used for crystallization experiments was taken from a CMC batch prepared substantially as described in steps 1 to 4 above, which was subsequently found to comprise a mixture of approximately 67 percent of form A1 and approximately 33 percent of Form A2. 
     Form A1 
     Several slow evaporations crystallisations as detailed in Table 1 below gave crystals using solvents ethyl acetate, isopropyl, acetate, MEK and 2-methoxyethanol that were used for establishing the crystal and molecular structure of Form A1 as shown in  FIGS. 1 and 2 . It has also been found that a second recrystallization from ethanol of Compound A obtained in step 4 above also yields a substantially pure form of polymorph A1. It is critical in the further recrystallization from ethanol that no moisture from the atmosphere be allowed to condense on the wet cake of compound A. This is because impurities have the potential to form in the presence of water. The preferred recrystallisation process from ethanol then dries the recrystallized compound in a freeze dryer at room 
     temperature. 
     
       
         
               
             
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Results of the slow evaporation crystallization experiments. 
               
             
          
           
               
                 Solvents 
                 μl of solvents 
                 Temperature 
                 Crystals 
               
               
                   
               
               
                 1,4-Dioxane 
                 400 
                 RT 
                 Form A1 
               
               
                 MEK* 
                 400 
                 RT 
                 Too small 
               
               
                 Trifluoroethanol 
                 400 
                 RT 
                 Too small 
               
               
                 Ethyl Acetate* 
                 400 
                 RT 
                 Form A1 
               
               
                 Isopropyl acetate* 
                 400 
                 RT 
                 Form A1 
               
               
                 1,2-Dimethoxyethane 
                 400 
                 RT 
                 Glass 
               
               
                 2-Methoxyethanol 
                 400 
                 RT 
                 Form A1 
               
               
                 3-Methyl-2-butanone* 
                 400 
                 RT 
                 Form A1 
               
               
                 DMF 
                 400 
                 RT 
                 Glass 
               
               
                 Iso-propanol* 
                 400 
                 RT 
                 Too small 
               
               
                 Ethanol/Water (80:20)* 
                 400 
                 RT 
                 Too small 
               
               
                 Ethanol/Water (90:10)* 
                 400 
                 RT 
                 Too small 
               
               
                   
               
               
                 *To dissolve the material, the mixture was warmed up to 60° C. and kept at this temperature for approximately 30 min. Following, it was left for crystallization at room temperature (RT). 
               
               
                 MEK: Methylethyl ketone. 
               
               
                 DMF: Dimethylformamide. 
               
             
          
         
       
     
     Approximately 3-8 mg of Compound A was placed into 8 ml vials to which 400 μL of solvent as detailed in Table 1 was added. The experiments were carried out at room temperature. Each 8 ml vial was placed in a 20 ml vial that was then closed and a small hole was pierced in the cap of the 20 ml vials. The vials were left at room temperature. A single colorless crystal (plate shaped) of approximate size 0.35×0.25×0.05 mm was directly collected from the ethyl acetate solution and mounted on a goniometer. The measurements were performed at room temperature (296K). The final crystallographic data are as shown in Table 2 below: 
     
       
         
               
             
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                 Crystal data and Structure refinement for Compound A - Form A1 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Identification 
                 Form A1 
               
               
                 Empirical Formula 
                 C 15 H 20 N 6 O 6 ; 
               
               
                 Formula Weight 
                 Mr = 380.37; 
               
               
                 Crystal System 
                 Monoclinic crystal system; 
               
               
                 Space Group 
                 P2 1  space group; 
               
               
                 Unit Cell Dimensions 
                 a = 5.546(2) Å; 
               
               
                   
                 b = 7.107(2) Å; 
               
               
                   
                 c = 21.929(9) Å; 
               
               
                   
                 V = 858.8(5) Å 3   
               
               
                 [degrees] 
                 96.501(8) 
               
               
                 Z 
                 2. 
               
               
                 T[K] 
                 296(2) 
               
               
                 Å 
                 0.71073 
               
               
                 D c  [g/cm 3 ] 
                 1.471 
               
               
                 [mm −1 ] 
                 0.115 
               
               
                 F(000) 
                 400 
               
               
                 Crystal size [mm 3 ] 
                 0.35 × 0.25 × 0.05 
               
               
                 Range of data collection [degrees] 
                 3-27.4 
               
               
                 Reflections collected 
                 5868 
               
               
                 Independent reflections 
                 3315 [R int  = 0.0268] 
               
               
                 Completeness to = 27.4 [%] 
                 97.8 
               
               
                 Max. and min. transmission 
                 0.9942 and 0.9606 
               
               
                 Data/restraints/parameters 
                 3315/1/289 
               
               
                 Goodness-of-fit on F 2   
                 1.063 
               
               
                 Final R indices[l &gt; 2(l)] 
                 R1 = 0.0418, wR2 = 0.0970 
               
               
                 R indices (all data) 
                 R1 = 0.0556, wR2 = 0.1050 
               
               
                 Absolute structure parameter 
                 −0.1(12) 
               
               
                 Extinction coefficient 
                 0.081(8) 
               
               
                   
               
             
          
         
       
     
     The single crystal measurements were performed on Nonius Kappa-CCD diffractometer equipped with Oxford Cryostream Liquid Nitrogen Cooler using MO K radiation. The data for form A1 was collected up to theta=27.5° at 296K yielding 5868 reflections. Data reduction was performed using HKL Scalepack (Otwinowski &amp; Minor 1997) and cell parameters were obtained using Denzo and Scalepak (Otwinowski &amp; Minor 1997) from 2569 within theta range 1 to 27.5°. The structure was solved using direct methods by SHELXZ-97 (Sheldrick, G. M. 1997a). 
     In addition to the single x-ray crystallography data, powder diffraction data was also collected on a D8 Advance diffractometer using CuK α1  radiation (1.54016 Å) with germanium monochromator at Room Temperature. The data were collected from 2.5 to 32.5° theta with 0.016° theta steps on solid state LynxEye detector. The sample was measured in an 8 mm long capillary with 0.5 mm diameter. 
     Crystalline anhydrous polymorph form A1 is preferably characterized by a PXRD spectra having peaks at about 17.5, 20.5, 21.2, 22.7, 24.8, 33.2 and 42.1+0.2 degrees 2 theta. 
     In Table 3 the intensity, 2 theta and D spacing are listed together with the HKL indices. Because intensity as well as 2 theta values are dependent on the radiation used, therefore the D spacing was implemented. The radiation used was CuK α1 . 2 
                                                                                 TABLE 3                   HKL, 2 theta, D spacing and intensity from       the powder diffraction of Form A1 (P2 1 )                h   k   l   D spacing   2θ   Intensity                        0   0   1   21.757   4.058   3.070(29)            0   0   2   10.878   8.121   1.910(36)            0   0   3   7.252   12.194   0.623(59)            0   1   1   6.745   13.115   0.025(65)            0   1   2   5.943   14.895   2.323(93)            −1   0   1   5.498   16.109   3.19(30)           1   0   0   5.480   16.162   6.84(33)           0   0   4   5.439   16.283   0.91(15)           −1   0   2   5.192   17.064   1.06(15)           1   0   1   5.147   17.214   4.07(16)           0   1   3   5.072   17.472   11.87(17)            −1   0   3   4.697   18.878   0.92(18)           1   0   2   4.642   19.104   16.40(23)            0   0   5   4.351   20.393    0.5(17)           1   −1   −1   4.346   20.420   20.7(26)           1   1   0   4.337   20.462   19.5(15)           0   1   4   4.317   20.559   10.14(40)            1   −1   −2   4.190   21.187   42.01(46)            1   1   1   4.166   21.309   7.14(92)           −1   0   4   4.160   21.342   1.29(81)           1   0   3   4.106   21.624   1.29(24)           1   −1   −3   3.916   22.686   77.44(52)            1   1   2   3.884   22.876   12.02(34)            0   1   5   3.709   23.971   2.41(28)           −1   0   5   3.664   24.270   0.03(28)           0   0   6   3.626   24.530   1.18(60)           1   0   4   3.617   24.590   5.78(63)           1   −1   −4   3.589   24.791   22.15(38)            1   1   3   3.554   25.035   5.20(97)           0   2   0   3.547   25.082   14.93(93)            0   2   1   3.501   25.419   9.96(33)           0   2   2   3.373   26.405   0.01(32)           1   −1   −5   3.256   27.371   1.19(38)           −1   0   6   3.238   27.525   0.76(70)           0   1   6   3.229   27.604    2.8(13)           1   1   4   3.223   27.658   12.60(99)            1   0   5   3.198   27.873   0.26(46)           0   2   3   3.187   27.977   0.30(44)           0   0   7   3.108   28.699   0.65(36)           1   −2   −1   2.981   29.953   14.3(20)           1   2   0   2.978   29.982    0.2(25)           0   2   4   2.971   30.050   5.21(90)           1   −1   −6   2.946   30.318   7.63(44)           1   −2   −2   2.929   30.494   1.64(66)           1   2   1   2.921   30.581    0.0(11)           1   1   5   2.916   30.638   2.36(86)           −1   0   7   2.881   31.021   5.24(41)           1   0   6   2.848   31.390    2.6(62)           0   1   7   2.847   31.397    0.1(62)           1   −2   −3   2.831   31.580   11.04(53)            1   2   2   2.819   31.720   3.23(48)           −2   0   1   2.766   32.335   1.54(44)           0   2   5   2.750   32.539    4.6(62)           −2   0   2   2.749   32.548    1.3(64)           2   0   0   2.740   32.657   1.45(63)           0   0   8   2.720   32.908   0.37(43)           1   −2   −4   2.699   33.163   18.54(59)            −2   0   3   2.689   33.286   0.53(97)           1   2   3   2.684   33.350   0.65(92)           2   0   1   2.673   33.500    2.6(11)           1   −1   −7   2.669   33.550   0.12(97)           1   1   6   2.643   33.894   0.46(44)           −2   0   4   2.596   34.521   1.31(47)           −1   0   8   2.583   34.701   0.04(83)           2   −1   −1   2.577   34.778    1.6(15)           2   0   2   2.574   34.832    0.3(12)           2   −1   −2   2.563   34.978   1.06(92)           2   1   0   2.556   35.081     0(15)           1   0   7   2.556   35.086     3(15)           1   −2   −5   2.549   35.182    9.2(11)           0   1   8   2.539   35.316    2.7(16)           0   2   6   2.536   35.369    2.3(26)           1   2   4   2.533   35.412    4.6(16)           2   −1   −3   2.515   35.673   7.10(49)           2   1   1   2.501   35.874   0.56(48)           −2   0   5   2.479   36.208   0.01(47)           2   1   5   2.089   43.279    5.9(61)           1   −2   −8   2.088   43.295    0.3(65)           2   2   2   2.083   43.403    2.0(33)           0   1   10   2.080   43.471      2(110)           −2   0   8   2.080   43.474      1(120)           0   3   5   2.078   43.519    0.7(59)           1   2   7   2.074   43.615    9.8(13)           1   −3   −4   2.056   44.008    9.4(15)           2   0   6   2.053   44.070    0.0(17)           1   3   3   2.049   44.156    2.0(11)           1   −1   −10   2.036   44.452   5.63(92)           2   −2   −5   2.032   44.555    7.3(10)           1   1   9   2.019   44.850    2.3(18)           2   2   3   2.018   44.889    0.0(21)           0   2   9   1.998   45.362      0(670)           2   −1   −8   1.996   45.403     70(970)                    
Form A2
 
     None of the crystallization trials or techniques attempted, including (i) slow evaporation of solvent, (ii) vapor diffusion of non polar solvent into liquid solution of Compound A and (iii) polar solvent and temperature controlled crystallization with slow cooling rate; yielded suitable crystals of Form A2 for single crystal analysis. In some experiments, such as, for example, in the temperature controlled crystallizations using various mixtures of ethanol/water, very thin needles were obtained. In most of the cases the crystals seemed to be twinned crystals, however none of these crystals gave enough reflections to obtain proper cell parameters. These crystals were however used to attempt X-ray powder diffraction. Therefore the X-ray Powder Diffraction Pattern (XRPD) was obtained and attempts were then made for solving the structure of the Form A2 from the powder data. The first step was to obtain the proper unit cell. After several trials, two possible cell settings were obtained. Both were orthorhombic although with different Bravais face centering. One of these cells was a face centred cell C, while the other was primitive P. Based on the fact that the cell C could be transformed into a smaller one, namely P, the latter was refined and attempts to solve the structure with this configuration setting were made. Also, with the P cell the asymmetric unit was reduced to 1 molecule with C it concerned 2 symmetry independent molecules. For the cell refinement the Pawley fit was used. A Pawley fit based on the high resolution X-ray diffraction pattern was used to check the purity of the sample. The main purpose of the Pawley fit is to refine cell parameters from the complete pattern. In the Pawley method, profiles are analytical, their width is constrained to follow a Caglioti law with the three refinable parameters U, V, W as defined in most of the Rietveld-derived software. The software used for calculation in this project was Topas with following criteria of fit: 
     Y o,m  and Y c,m  are the observed and calculated data, respectively at data point m. 
     M the number of data points, 
     P the number of parameters, 
     W m  the weighting given to data point m which for counting statistics is given by w m =1/σ(Y o,m ) 2  where σ(Y o,m ) is the error in Y o,m   
     
       
         
           
             
               
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                 TABLE 4 
               
               
                   
               
               
                 Parameters of the Pawley fit for Compound A - Form A2 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Identification 
                 Form A2 
               
               
                   
                 T[K] 
                 293(2) 
               
               
                   
                 Å 
                 1.54056 
               
               
                   
                 Crystal System 
                 Orthorhombic crystal system; 
               
               
                   
                 Space Group 
                 P2 1 2 1 2 1  space group; 
               
               
                   
                 Unit Cell Dimensions 
                 a = 5.51796(17) Å; 
               
               
                   
                   
                 b = 7.14615(29) Å; 
               
               
                   
                   
                 c = 42.9738(29) Å; 
               
               
                   
                   
                 V = 1694.55(14) Å 3   
               
               
                   
                 Capillary size 
                 0.5 × 0.8 
               
               
                   
                 Range for data collection 
                 2-22.5 
               
               
                   
                 R exp   
                 1.52 
               
               
                   
                 R wp   
                 2.64 
               
               
                   
                 Rp 
                 1.91 
               
               
                   
                 R Bragg   
                 7.8 
               
               
                   
                 GOF 
                 1.74 
               
               
                   
               
             
          
         
       
     
     For the structure solution, the Topas 3.0 software was employed (Bruker-AXS, 2005) using simulated annealing method. The model was built on the Z-matrix and several torsion angles were set as free variables. The obtained model was not refined except for the unit cell. The H-atoms were included based on geometry and H-Bond scheme.  FIG. 3  shows the molecular structure of Form 2 of Compound A and  FIG. 4  shows the crystal packing and the H-bond scheme. 
     XRPD patterns were obtained using a high-throughput XRPD set-up. The plates were mounted on a Bruker GADDS diffractometer equipped with a Hi-Star area detector. The XRPD platform was calibrated using Silver Behenate for the long d-spacings and Corundum for the short d-spacings. 
     Data collection was carried out at room temperature using monochromatic CuKα radiation in the 2-theta region between 1.5 degrees and 41.5 degrees, which is the most distinctive part of the XRPD pattern between the polymorph forms. The diffraction pattern of each well was collected in 2 theta ranges (1.5 degrees≦2 theta≦21.5 degrees for the first frame, and 19.5 degrees≦2 theta≦41.5 degrees for the second) with an exposure time of 30 seconds for each frame. No background subtraction or curve smoothing was applied to the XRPD patterns. The carrier material used during XRPD analysis was transparent to X-rays and contributed only slightly to the background. 
     Crystalline anhydrous polymorph form A2 is preferably characterized by PXRD spectra having peaks at about 16.9, 18.1, 19.1, 20.8, 21.3, 22.0, 22.8, 23.8, 24.9, 25.0, 29.1, 29.8, 34.2 and 35.8+0.2 degrees 2 theta. 
     In Table 5 the intensity, 2 theta and D spacing are listed together with the HKL indices. Because intensity as well as 2 theta values are dependent on the radiation used, therefore the D spacing was implemented. The radiation used was CuK α1 . 2 
                                                                                 TABLE 5                   HKL, 2 theta, D spacing and intensity from       the powder diffraction of Form A2 (P2 1 2 1 2 1 )                h   k   l   D spacing   2θ   Intensity                        0   0   2   21.487   4.109   3.341(28)            0   0   4   10.743   8.223   2.277(38)            0   0   6   7.162   12.348   0.690(57)            0   1   1   7.049   12.547   0.802(58)            0   1   2   6.781   13.045   0.032(57)            0   1   3   6.395   13.837   1.088(68)            0   1   4   5.950   14.877   2.330(82)            0   1   5   5.495   16.117   2.50(22)           1   0   1   5.473   16.182   16.69(24)            0   0   8   5.372   16.489   0.31(12)           1   0   2   5.345   16.574   0.02(12)           1   0   3   5.149   17.207   0.78(11)           0   1   6   5.059   17.517   9.55(14)           1   0   4   4.908   18.058   15.49(17)            0   1   7   4.657   19.043   2.50(33)           1   0   5   4.643   19.098   18.42(35)            1   0   6   4.371   20.300    0.0(12)           1   1   0   4.367   20.317   14.0(13)           1   1   1   4.345   20.423   21.46(33)            0   0   10   4.297   20.652    4.4(20)           0   1   8   4.294   20.669   14.2(23)           1   1   2   4.280   20.737   34.73(53)            1   1   3   4.178   21.251   62.18(36)            1   0   7   4.104   21.637   3.26(21)           1   1   4   4.046   21.951   64.81(39)            0   1   9   3.970   22.375   3.18(21)           1   1   5   3.894   22.821   67.15(41)            1   0   8   3.849   23.089   0.02(22)           1   1   6   3.729   23.844   23.77(31)            0   1   10   3.683   24.147   1.11(24)           1   0   9   3.611   24.636   5.44(27)           0   0   12   3.581   24.843   1.32(64)           0   2   0   3.573   24.900    0.0(10)           0   2   1   3.561   24.987   16.0(37)           1   1   7   3.559   25.001   57.1(34)           0   2   2   3.525   25.247   7.78(28)           0   2   3   3.467   25.675   0.11(25)           0   1   11   3.428   25.972   0.02(26)           0   2   4   3.390   26.264      0(1200)           1   0   10   3.390   26.264      0(1200)           1   1   8   3.389   26.278       13(11)           0   2   5   3.299   27.003   0.24(27)           1   1   9   3.223   27.658   6.71(31)           0   1   12   3.202   27.843   4.61(77)           0   2   6   3.197   27.882   0.02(89)           1   0   11   3.188   27.961   0.02(42)           0   2   7   3.088   28.889   3.68(33)           0   0   14   3.070   29.067   0.02(57)           1   1   10   3.063   29.129   13.39(58)            1   0   12   3.004   29.716    0.3(17)           0   1   13   3.000   29.754    0.3(90)           1   2   0   2.999   29.765    4.9(81)           1   2   1   2.992   29.839   23.29(88)            0   2   8   2.975   30.012   0.81(68)           1   2   2   2.970   30.060   4.79(66)           1   2   3   2.936   30.426   0.16(34)           1   1   11   2.912   30.680   1.09(34)           1   2   4   2.889   30.931   2.18(35)           0   2   9   2.861   31.241   3.31(36)           1   0   13   2.836   31.524   2.60(83)           1   2   5   2.832   31.569   13.87(87)            0   1   14   2.820   31.700   0.94(41)           1   1   12   2.769   32.301    1.3(12)           1   2   6   2.766   32.335   12.9(14)           2   0   0   2.759   32.425   2.17(88)           2   0   1   2.753   32.493   3.93(89)           0   2   10   2.747   32.564   2.65(63)           2   0   2   2.737   32.698   1.03(41)           2   0   3   2.709   33.037   0.47(39)           1   2   7   2.695   33.219   13.32(50)            0   0   16   2.686   33.333   0.44(92)           1   0   14   2.682   33.376   0.02(88)           2   0   4   2.672   33.507   1.62(43)           0   1   15   2.659   33.677   0.31(39)           0   2   11   2.637   33.974    0.0(33)           1   1   13   2.636   33.985    1.5(34)           2   0   5   2.627   34.103   3.97(60)           1   2   8   2.619   34.214   14.87(53)            2   0   6   2.575   34.818    0.3(46)           2   1   0   2.574   34.829    2.2(52)           2   1   1   2.569   34.893   4.43(92)           2   1   2   2.556   35.086   4.65(43)           1   0   15   2.543   35.270    0.0(11)           1   2   9   2.540   35.312   11.6(13)           2   1   3   2.533   35.405   0.15(98)           0   2   12   2.529   35.461   5.87(80)           2   0   7   2.517   35.648    0.0(15)           0   1   16   2.514   35.683    0.0(25)           1   1   14   2.511   35.724    2.5(15)           2   1   4   2.503   35.847   15.03(56)            2   1   5   2.466   36.409   3.57(54)           1   2   10   2.459   36.504   1.95(65)           2   0   8   2.454   36.585   0.02(56)           0   2   13   2.427   37.018   2.26(64)           2   1   6   2.422   37.086   1.62(68)           1   0   16   2.415   37.201   1.13(49)           1   1   15   2.396   37.514   2.28(58)           2   0   9   2.389   37.623    4.3(25)           0   0   18   2.387   37.646    0.0(30)           0   1   17   2.383   37.716    0.6(17)           1   2   11   2.379   37.785    8.3(82)           0   3   1   2.378   37.795    2.2(80)           2   1   7   2.374   37.873   2.95(98)           0   3   2   2.368   37.974   1.72(55)           0   3   3   2.350   38.273   0.02(46)           0   2   14   2.328   38.639    6.6(11)           0   3   4   2.326   38.687    2.9(18)           2   0   10   2.322   38.754    0.9(66)           2   1   8   2.321   38.764    1.8(59)           1   2   12   2.299   39.146    1.3(32)           1   0   17   2.298   39.167    0.0(43)           0   3   5   2.296   39.214   11.8(17)           1   1   16   2.288   39.351   2.64(54)           2   1   9   2.266   39.753    5.2(23)           0   1   18   2.264   33.775    0.0(26)           0   3   6   2.260   39.850   1.52(90)           2   0   11   2.254   39.973   4.10(57)           0   2   15   2.235   40.318   1.37(55)           1   2   13   2.221   40.582    0.5(43)           0   3   7   2.221   40.591    4.1(43)           2   1   10   2.208   40.835   0.02(60)           1   0   18   2.191   41.165    0.0(15)           1   1   17   2.188   41.230     3(14)           1   3   0   2.187   41.246     1(25)           2   0   12   2.186   41.274     2(24)           1   3   1   2.184   41.302     6(49)           2   2   0   2.184   41.310     0(40)           2   2   1   2.181   41.366    8.8(38)           0   3   8   2.178   41.433    2.1(33)           1   3   2   2.176   41.469   11.6(29)           2   2   2   2.173   41.533    2.8(12)           1   3   3   2.162   41.747   11.1(12)           2   2   3   2.159   41.810    7.1(18)           0   1   19   2.156   41.860    2.7(15)           2   1   11   2.149   42.003    5.0(99)           0   0   20   2.149   42.016     0(14)           0   2   16   2.147   42.052    0.9(81)           1   2   14   2.145   42.087    2.4(56)           1   3   4   2.143   42.132    3.6(29)           2   2   4   2.140   42.195    6.3(12)           0   3   9   2.132   42.370   5.30(72)           1   3   5   2.119   42.624    2.3(32)           2   0   13   2.118   42.651    0.2(49)           2   2   5   2.116   42.686    6.8(25)           1   1   18   2.095   43.148    1.4(22)           1   0   19   2.093   43.194    0.2(81)           1   3   6   2.092   43.219     3(11)           2   1   12   2.090   43.254    6.0(89)           2   2   6   2.089   43.280    2.5(44)           0   3   10   2.083   43.398   0.10(84)           1   2   15   2.072   43.657   6.91(88)           0   2   17   2.064   43.835    0.0(11)           1   3   7   2.060   43.913    5.9(22)           0   1   20   2.058   43.968     4(18)           2   2   7   2.057   43.974     0(17)           2   0   14   2.052   44.098   0.99(86)           0   3   11   2.034   44.512    1.2(11)           2   1   13   2.031   44.581    6.0(12)           1   3   8   2.026   44.704   10.2(16)           2   2   8   2.023   44.764    8.8(23)           1   1   19   2.008   45.105     0(38)           1   0   20   2.002   45.252      0(2700)           1   2   16   2.001   45.286      0(4300)                    
Controlling the Formation of the Form of Polymorph
 
     It has been found that the formation of the particular polymorphic form can be controlled. As described above the Form A1 can be obtained predominantly via recrystallization from ethanol or under slow evaporation conditions. 
     It has also been established that ripening or curing of Compound A particles suspended in an aqueous suspension formulated for ocular delivery at 40 degrees C. for a relatively short period of time formed polymorph form A2 from polymorph form A1. The aqueous suspension samples were kept at 40 degrees C. for up to 108 hours and monitored by particle size measurement, XRPD and microphotography. Particle size measurements showed that average sizes increased significantly over 15 hours. Thereafter, sizes remained effectively constant to 108 hours. XRPD analyses indicated a change in polymorph content from about 74% A1 to 26% A2 at time zero to 0% A1 to 100% A2 at 108 hours at 40 degrees C.  FIG. 7  shows the conversion of form A1 to A2 over time. Also, habit changes coupled with A2 growth were reflected in the XRPD patterns and could be monitored by a difference in selected peak intensities from planes within the crystal lattice perpendicular to the c axis that change in intensity as the habit of the crystal changes. The intensity differences changed up to 9 hours and remained constant thereafter indicating that the habit changes were completed during this time. Microphotographs showed blade or plate-like crystal habits of particles in suspension. 
     When the aqueous suspension ocular formulation containing Compound A in the A1 polymorph is stored at 2-8° C., a temperature required to limit decomposition of Compound A over long term storage, the habit of the suspended particles changes slowly over a period of 6 to 12 months. During this time the small irregular particles of suspended drug change to rod-like habits, with many particles having a length along the longest dimension over 100 microns. These changes make it much more difficult to resuspend Compound A particles by sonication and shaking in order to form a homogeneous suspension for dosing. 
     The conversion of the A1 form to the A2 form has been found to limit any further changes to particle habit, size or polymorph content when the aqueous suspension, which is suitable for ocular delivery of the drug, is stored over a 6 month period at either 5° C. or 25° C. Also, the cured aqueous suspension is more easily resuspended by shaking, a favourable characteristic for suspension formulations for ocular drug delivery. 
     The particle size analyses were performed on a Cilas 1180 Particle Size Analyzer. The parameters used were liquid mode, sample refractive index=1.62 (determined using Cargille immersion oils), liquid refractive index=1.333 (value for water), 30 second measurement, 180 rpm stirring, 120 rpm pump circulation, no sonication, 5 repeat measurements. 
     Formulation Example 
     A batch of sterile material of Compound A was prepared as described above under the “Synthesis of Compound A”. The resulting Compound A material was then sterilized with gamma irradiation at up to 40 kGray and then formulated into the following aqueous formulations: 
     Aqueous Formulation 
     
       
         
               
               
               
             
           
               
                   
               
               
                   
                 Ingredient 
                 %, W/V 
               
               
                   
               
             
             
               
                   
                 Compound A 
                 0.152-0.76 
               
               
                   
                 Sodium CMC 
                 0.7 
               
               
                   
                 Benzalkonium Chloride 
                 0.01 
               
               
                   
                 Polysorbate 80 
                 0.3 
               
               
                   
                 Citric Acid Monohydrate 
                 0.152 (7 mM) 
               
               
                   
                 NaOH/HCl 
                 pH 5.1 ± 0.1 
               
               
                   
                 NaCl 
                 q.s. to 270-330 mOsm 
               
               
                   
                 Purified Water 
                 q.s. to 100.00 
               
               
                   
               
             
          
         
       
     
     Various concentrations of Compound A formulation lots were prepared from 0.152, 0.30, 0.61, 0.91, 2.42, 0.46, 0.76%, W/V to provide for the ability to deliver different levels of Compound A per drop of formulation. For example one drop of the 0.152%, W/V of compound A would deliver 50 mcg per drop, 0.30%, W/V would deliver 100 mcg per drop, right through to 0.76% W/V delivering 250 mcg per drop. The formulation lots were then heated to undergo the curing step and convert the A1 polymorph form of Compound A to the A2 polymorph form of Compound A. The curing step was undertaken by placing the formulation lots at 40 degrees C. for 48 hours and then reverting the formulations lots to the desired longer term storage conditions for stability studies. 
     Two of the formulation lots, namely 0.46% W/V of Compound A and a 0.76% W/V were studied for long term stability and particle size growth at 5 degrees Celsius and 25 degrees Celsius for 6 months. Two of the formulation lots, namely 0.46% W/V of Compound A and a 0.76% W/V were studied for long term stability and particle size growth at 5 degrees Celsius for 18 months. The results are tabulated below in Table 6. 
     
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 6 
               
               
                   
               
               
                   
                   
                   
                   
                 Particle Size 
               
               
                   
                 Time 
                   
                   
                 Distribution 
               
               
                 Formulation 
                 (months) 
                 Impurities 
                 pH 
                 (microns) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 0.46% at 
                 0 
                 1% 
                 5.1 
                 X 10  = 1.746 
               
               
                 5° C. 
                   
                   
                   
                 X 50  = 6.992 
               
               
                   
                   
                   
                   
                 X 90  = 14.087 
               
               
                 0.46% at 
                 1 
                 1% 
                 5.0 
                 X 10  = 0.907 
               
               
                 5° C. 
                   
                   
                   
                 X 50  = 6.285 
               
               
                   
                   
                   
                   
                 X 90  = 13.485 
               
               
                 0.46% at 
                 3 
                 1% 
                 5.0 
                 X 10  = 1.792 
               
               
                 5° C. 
                   
                   
                   
                 X 50  = 7.082 
               
               
                   
                   
                   
                   
                 X 90  = 14.356 
               
               
                 0.46% at 
                 6 
                 1% 
                 5.1 
                 X 10  = 1.777 
               
               
                 5° C. 
                   
                   
                   
                 X 50  = 6.939 
               
               
                   
                   
                   
                   
                 X 90  = 13.698 
               
               
                 0.46% at 
                 12 
                 1% 
                 5.1 
                 X 10  = 1.398 
               
               
                 5° C. 
                   
                   
                   
                 X 50  = 6.679 
               
               
                   
                   
                   
                   
                 X 90  = 13.396 
               
               
                 0.46% at 
                 18 
                 1% 
                 5.1 
                 X 10  = 1.666 
               
               
                 5° C. 
                   
                   
                   
                 X 50  = 6.882 
               
               
                   
                   
                   
                   
                 X 90  = 13.074 
               
               
                 0.46% at 
                 0 
                 1% 
                 5.1 
                 X 10  = 1.746 
               
               
                 25° C. 
                   
                   
                   
                 X 50  = 6.416 
               
               
                   
                   
                   
                   
                 X 90  = 13.698 
               
               
                 0.46% at 
                 1 
                 1% 
                 5.0 
                 X 10  = 1.036 
               
               
                 25° C./60% RH 
                   
                   
                   
                 X 50  = 6.416 
               
               
                   
                   
                   
                   
                 X 90  = 13.698 
               
               
                 0.46% at 
                 3 
                 3% 
                 5.1 
                 X 10  = 1.656 
               
               
                 25° C./60% RH 
                   
                   
                   
                 X 50  = 6.705 
               
               
                   
                   
                   
                   
                 X 90  = 12.805 
               
               
                 0.46% at 
                 6 
                 4% 
                 5.0 
                 X 10  = 1.809 
               
               
                 25° C./60% RH 
                   
                   
                   
                 X 50  = 6.741 
               
               
                   
                   
                   
                   
                 X 90  = 12.380 
               
               
                 0.76% at 
                 0 
                 1% 
                 5.1 
                 X 10  = 1.524 
               
               
                 5° C. 
                   
                   
                   
                 X 50  = 6.773 
               
               
                   
                   
                   
                   
                 X 90  = 12.778 
               
               
                 0.76% at 
                 1 
                 1% 
                 5.1 
                 X 10  = 1.115 
               
               
                 5° C. 
                   
                   
                   
                 X 50  = 6.456 
               
               
                   
                   
                   
                   
                 X 90  = 12.944 
               
               
                 0.76% at 
                 3 
                 1% 
                 5.1 
                 X 10  = 1.455 
               
               
                 5° C. 
                   
                   
                   
                 X 50  = 6.745 
               
               
                   
                   
                   
                   
                 X 90  = 13.104 
               
               
                 0.76% at 
                 6 
                 1% 
                 5.1 
                 X 10  = 1.541 
               
               
                 5° C. 
                   
                   
                   
                 X 50  = 6.638 
               
               
                   
                   
                   
                   
                 X 90  = 11.833 
               
               
                 0.76% at 
                 12 
                 1% 
                 5.1 
                 X 10  = 1.407 
               
               
                 5° C. 
                   
                   
                   
                 X 50  = 6.635 
               
               
                   
                   
                   
                   
                 X 90  = 12.314 
               
               
                 0.76% at 
                 18 
                 1% 
                 5.1 
                 X 10  = 1.611 
               
               
                 5° C. 
                   
                   
                   
                 X 50  = 6.840 
               
               
                   
                   
                   
                   
                 X 90  = 12.672 
               
               
                 0.76% at 
                 0 
                 1% 
                 5.1 
                 X 10  = 1.524 
               
               
                 25° C./60% RH 
                   
                   
                   
                 X 50  = 6.773 
               
               
                   
                   
                   
                   
                 X 90  = 12.778 
               
               
                 0.76% at 
                 1 
                 1% 
                 5.1 
                 X 10  = 1.056 
               
               
                 25° C./60% RH 
                   
                   
                   
                 X 50  = 6.107 
               
               
                   
                   
                   
                   
                 X 90  = 11.551 
               
               
                 0.76% at 
                 3 
                 2% 
                 5.1 
                 X 10  = 1.446 
               
               
                 25° C./60% RH 
                   
                   
                   
                 X 50  = 6.691 
               
               
                   
                   
                   
                   
                 X 90  = 12.724 
               
               
                 0.76% at 
                 6 
                 3% 
                 5.1 
                 X 10  = 1.619 
               
               
                 25° C./60% RH 
                   
                   
                   
                 X 50  = 6.292 
               
               
                   
                   
                   
                   
                 X 90  = 10.240 
               
               
                   
               
             
          
         
       
     
     It can be seen from the results in Table 6 that the particle size distributions of the two formulation lots are stable over the time under the conditions tested. The results also show that the levels of impurities and pH remain stable for the formulations at 5 degrees Celsius over 18 months, while there is a slow increase in the impurities for the formulations held at 25 degrees Celsius over 6 months. 
     The present invention and its embodiments have been described in detail. However, the scope of the present invention is not intended to be limited to the particular embodiments of any process, manufacture, composition of matter, compounds, means, methods, and/or steps described in the specification. Various modifications, substitutions, and variations can be made to the disclosed material without departing from the spirit and/or essential characteristics of the present invention. Accordingly, one of ordinary skill in the art will readily appreciate from the disclosure that later modifications, substitutions, and/or variations performing substantially the same function or achieving substantially the same result as embodiments described herein can be utilized according to such related embodiments of the present invention. Thus, the following claims are intended to encompass within their scope modifications, substitutions, and variations to processes, manufactures, compositions of matter, compounds, means, methods, and/or steps disclosed herein.