Abstract:
An object of the present invention is to provide a novel salt form of a compound that exhibits an inhibitory effect on activated blood coagulation factor X, and is useful as a preventive and/or therapeutic drug for thrombotic diseases, and crystals thereof. The present invention provides N 1 -(5-chloropyridin-2-yl)-N 2 -((1S,2R,4S)-4-[(dimethylamino)carbonyl]-2-{[(5-methyl-4,5,6,7-tetrahydrothiazolo[5,4-c]pyridin-2-yl)carbonyl]amino}cyclohexyl)ethanediamide tartrate and crystals thereof, as a novel salt form of N 1 -(5-chloropyridin-2-yl)-N 2 -((1S,2R,4S)-4-[(dimethylamino)carbonyl]-2-{[(5-methyl-4,5,6,7-tetrahydrothiazolo[5,4-c]pyridin-2-yl)carbonyl]amino}cyclohexyl)ethanediamide and crystals thereof.

Description:
This application is a continuation of International Application No. PCT/JP2010/050128, filed on Jan. 8, 2010, entitled “ACTIVE BLOOD COAGULATION FACTOR INHIBITOR”, which claims the benefit of Japanese Patent Application Number JP 2009-004904, filed on Jan. 13, 2009, all of which are hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a salt of a compound that exhibits an inhibitory effect on activated blood coagulation factor X (FXa), and is useful as a preventive and/or therapeutic drug for thrombotic diseases, and to crystals thereof. 
     BACKGROUND OF THE INVENTION 
     N 1 -(5-chloropyridin-2-yl)-N 2 -((1S,2R,4S)-4-[(dimethylamino)carbonyl]-2-{[(5-methyl-4,5,6,7-tetrahydrothiazolo[5,4-c]pyridin-2-yl)carbonyl]amino}cyclohexyl)ethanediamide represented by the following formula (A) (hereinafter, also referred to as compound A): 
                                
exhibits an inhibitory effect on activated blood coagulation factor X, and its usefulness as a preventive and/or therapeutic drug for thrombotic diseases can be expected (Patent Literature 1 to 8). It is known that compound A is obtained as a hydrochloride or a p-toluenesulfonate monohydrate (Patent Literature 1 to 8).
 
     CITATION LIST 
     Patent Literature 
     
         
         Patent Literature 1: International Publication No. WO 03/000657 
         Patent Literature 2: International Publication No. WO 03/000680 
         Patent Literature 3: International Publication No. WO 03/016302 
         Patent Literature 4: International Publication No. WO 04/058715 
         Patent Literature 5: International Publication No. WO 05/047296 
         Patent Literature 6: International Publication No. WO 07/032498 
         Patent Literature 7: International Publication No. WO 08/129846 
         Patent Literature 8: International Publication No. WO 08/156159 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     It has been demanded to develop a novel salt form of a compound A, which is preferable as a bulk pharmaceutical. 
     Solution to Problem 
     To search for a novel salt form of compound A, the present inventors have conducted diligent studies on various salt forms other than the hydrochloride and p-toluenesulfonate monohydrate, and consequently completed the present invention by finding that the tartrate of compound A (hereinafter, also referred to as compound I), particularly, the (+)-tartrate monohydrate of compound A (hereinafter, also referred to as compound II), is useful as a bulk pharmaceutical, without problems in terms of moisture absorption and desorption characteristics, solubility, crystal stability, and chemical stability, compared with various other salts. 
     The present invention relates to: 
     [1] N 1 -(5-chloropyridin-2-yl)-N 2 -((1S,2R,4S)-4-[(dimethylamino)carbonyl]-2-{[(5-methyl-4,5,6,7-tetrahydrothiazolo[5,4-c]pyridin-2-yl)carbonyl]amino}cyclohexyl)ethanediamide tartrate; 
     [2] N 1 -(5-chloropyridin-2-yl)-N 2 -((1S,2R,4S)-4-[(dimethylamino)carbonyl]-2-{[(5-methyl-4,5,6,7-tetrahydrothiazolo[5,4-c]pyridin-2-yl)carbonyl]amino}cyclohexyl)ethanediamide(+)-tartrate monohydrate; 
     [3] a compound according to [2], which is crystals; 
     [4] a compound according to [3], which is crystals having characteristic peaks at diffraction angles (2θ) of 14.5, 17.2, 20.4, 21.3, 22.1, and 23.4)(°) by powder X-ray diffraction; 
     [5] a compound according to [3], which is crystals having characteristic peaks at diffraction angles (2θ) of 13.9, 17.1, 17.7, 18.6, 21.3, 21.8, and 24.3)(°) by powder X-ray diffraction; 
     [6] a compound according to [3], which is crystals having characteristic peaks at diffraction angles (2θ) of 13.9, 16.9, 17.5, 18.5, 21.4, and 22.1)(°) by powder X-ray diffraction; 
     [7] a pharmaceutical drug comprising a compound according to any one of [1] to [6] as an active ingredient; and 
     [8] an activated blood coagulation factor X inhibitor comprising a compound according to any one of [1] to [6] as an active ingredient. 
     In the present specification, “crystal” refers to a solid whose internal structure is composed of constituent atoms (or groups of atoms) three-dimensionally arranged in an ordered repeating pattern, and is distinguished from amorphous solids free from such an ordered internal structure. 
     In the present specification, “salt” also encompasses salts of solvate forms, for example, salts of hydrate forms, unless otherwise specified. 
     In the present specification, “tartaric acid” means either (+)-tartaric acid or (−)-tartaric acid, or both, unless otherwise specified. 
     In the present specification, “aqueous solvent” refers to a mixed solvent of water and a solvent other than water. For example, a mixed solvent of water and ethanol is also referred to as aqueous ethanol, and a mixed solvent of water and isopropyl alcohol is also referred to as aqueous isopropyl alcohol. 
     In the present specification, “%” used in the “% aqueous solvent” represents the proportion of water to the mixed solvent of water and solvent other than water. For example, aqueous ethanol having a water proportion of 20% is also referred to as 20% aqueous ethanol. 
     N 1 -(5-chloropyridin-2-yl)-N 2 -((1S,2R,4S)-4-[(dimethylamino)carbonyl]-2-{[(5-methyl-4,5,6,7-tetrahydrothiazolo[5,4-c]pyridin-2-yl)carbonyl]amino}cyclohexyl)ethanediamide represented by the following formula (A): 
                                
is identified by the International Nonproprietary Name (INN) of edoxaban (N-(5-chloropyridin-2-yl)-N′-[(1S,2R,4S)-4-(N,N-dimethylcarbamoyl)-2-(5-methyl-4,5,6,7-tetrahydro[1,3]thiazolo[5,4-c]pyridine-2-carboxamido)cyclohexyl]oxamide).
 
     Compound A can be produced according to a method described in Patent Literature 1 to 8 or a method equivalent thereto. 
     The (+)-tartrate monohydrate of compound A (compound II) can be obtained, for example, by adding an equimolar amount of a solution of (+)-tartaric acid in ethanol to compound A. 
     The crystals of compound II of the present invention can be produced, for example, by dissolving compound II in an appropriate solvent, performing pH adjustment, solution concentration, and so on, and bringing compound II to a supersaturated state for deposition. 
     The deposition of the crystals may be initiated spontaneously in a reaction vessel, and can also be initiated or promoted by inoculating seed crystals, or providing ultrasonic stimulation or mechanical stimulation such as the scrubbing of the reactor surface. 
     The temperature to crystallize compound II into crystals is preferably 0° C. to 40° C., more preferably 20° C. to 30° C. 
     The deposited crystal can be isolated by, for example, filtration, centrifugation, or decantation. The isolated crystals can be washed, if necessary, with an appropriate solvent. 
     Examples of the solvent for washing the crystals of compound II include water, ethanol, isopropanol, acetone, ethyl acetate, toluene, acetonitrile, methyl acetate, and ether. The solvent is preferably ethanol. 
     The isolated crystals can be dried, usually at a temperature of 10° C. to 100° C., preferably 30° C. to 50° C., until the weight becomes almost constant. The drying of the crystals can also be performed, if necessary, in the presence of a desiccant such as silica gel or calcium chloride, or under reduced pressure. 
     The dried crystals may be allowed to absorb moisture usually at a temperature of 10° C. to 30° C. and at 20% to 90% relative humidity, preferably at a temperature of 20° C. to 30° C. and at 50% to 80% relative humidity, until the weight becomes almost constant. 
     The obtained crystals can be recrystallized or slurry-purified, to improve their purity and quality. 
     The recrystallization of compound II of the present invention is achieved by a method usually used in the field of organic synthetic chemistry. Specifically, examples of the solvent used in the recrystallization of compound II of the present invention include water, methanol, ethanol, acetone, aqueous methanol, aqueous ethanol, aqueous 2-propanol, aqueous acetone, and aqueous acetonitrile. The solvent is preferably aqueous methanol, aqueous ethanol, aqueous 2-propanol, aqueous acetone, or aqueous acetonitrile. 
     Slurry purification is the procedure of suspending crystals of the compound in an appropriate solvent, stirring the suspension, and then isolating the crystals again. Examples of the solvent used in the slurry purification of compound II of the present invention include water, methanol, ethanol, 2-propanol, acetone, acetonitrile, methylene chloride, toluene, methyl acetate, ethyl acetate, pentane, tetrahydrofuran, N,N-dimethylformamide, water, hexane, diisopropyl ether, ether, aqueous ethanol, aqueous 2-propanol, and aqueous acetone. The solvent is preferably water, methanol, ethanol, 2-propanol, acetone, acetonitrile, ethyl acetate, pentane, aqueous ethanol, aqueous 2-propanol, or aqueous acetone. 
     Compound II forms crystalline polymorphs (Forms I, II, and III) in the recrystallization, as described later. Moreover, compound II also forms crystalline polymorphs (Forms II and III) in the slurry purification. Form I has characteristic peaks at diffraction angles (2θ) of 14.5, 17.2, 20.4, 21.3, 22.1, and 23.4)(°) by powder X-ray diffraction (Form I of  FIG. 8 ). Form II has characteristic peaks at diffraction angles (2θ) of 13.9, 17.1, 17.7, 18.6, 21.3, 21.8, and 24.3)(°) by powder X-ray diffraction (Form II of  FIG. 8 ). Form III has characteristic peaks at diffraction angles (2θ) of 13.9, 16.9, 17.5, 18.5, 21.4, and 22.1)(°) by powder X-ray diffraction (Form III of  FIG. 8 ). 
     The crystals of compound II thus obtained were highly soluble in water compared with compound A, as described later. 
     Moreover, when the crystals of compound II were stored for 4 days under three standard relative humidity conditions at 25° C., they were stable without change both in weight and in crystal form. On the other hand, crystals of the hydrobromide of compound A exhibited a great increase in weight. 
     Furthermore, the moisture absorption and desorption characteristics of the crystals of compound II were studied and used as an index for long-term storage stability. As a result, the crystals of compound II had 1% or less weight change at 40% to 60% relative humidity, and exhibited favorable moisture absorption and desorption characteristics. 
     A pharmaceutical drug comprising the salt and/or crystals of the present invention as an active ingredient is preferably provided in the form of a pharmaceutical composition comprising the salt and/or crystals of the present invention as an active ingredient and one or two or more pharmaceutical additives. The dosage form of the pharmaceutical drug of the present invention is not particularly limited, and it can be administered orally or parenterally, and is preferably administered orally. 
     The salt and/or crystals of the present invention exhibits a high inhibitory effect on activated blood coagulation factor X (FXa), and is thus useful as an anticoagulant agent or as a preventive and/or therapeutic agent for thrombosis or embolism. The pharmaceutical composition of the present invention is useful as a pharmaceutical drug for mammals including humans, as an activated blood coagulation factor Xa inhibitor, as an anticoagulant agent, as a preventive and/or therapeutic agent for thrombosis or embolism, as a preventive and/or therapeutic agent for thrombotic diseases, for example, as a preventive (in the present specification, prevention encompasses secondary prevention) and/or therapeutic agent for cerebral infarction, cerebral embolism, myocardial infarction, angina pectoris, unstable angina, acute coronary syndrome (ACS), pulmonary infarction, pulmonary embolism, thromboembolism or seizure accompanying nonvalvular atrial fibrillation (NVAF), deep vein thrombosis, disseminated intravascular coagulation syndrome, thrombosis after prosthetic valve/joint replacement, thromboembolism after total hip replacement (THR), thrombosis and reocclusion after revascularization, thrombosis at the time of extracorporeal circulation, blood coagulation at the time of blood collection, Buerger&#39;s disease, thromboembolism accompanying systemic inflammatory response syndrome (SIRS), or thromboembolism accompanying multiple organ dysfunction syndrome (MODS), or as a bulk pharmaceutical for these preventive and/or therapeutic agents. The pharmaceutical drug comprising the salt and/or crystals of the present invention is also useful in terms of no necessity for concern about the possibility of sulfonic acid ester formation. 
     Examples of pharmacologically or pharmaceutically acceptable additives used in the production of the pharmaceutical composition can include, but are not limited to, excipients, disintegrants or disintegration aids, binders, lubricants, coating agents, pigments, diluents, bases, solubilizers or solubilization aids, tonicity agents, pH adjusters, stabilizers, propellants, and adhesives. 
     Examples of preparations suitable for oral administration can include tablets, powders, granules, and capsules. Moreover, examples of preparations suitable for parenteral administration can include injections, drops, suppositories, inhalants, and patches. Of these, capsules or tablets or the like are preferable. 
     The dose of the pharmaceutical drug of the present invention is not particularly limited, and can be selected appropriately according to various conditions such as the age, body weight, and conditions of a patient. It is preferred to administer the pharmaceutical drug of the present invention at a dose of 1 mg to 1000 mg, preferably 5 mg to 500 mg, more preferably 5 mg to 300 mg, even more preferably 5 mg to 100 mg of the active ingredient per day in an adult human, which is administered in one portion or in several portions, preferably in one portion or in two portions, per day, according to the conditions. 
     ADVANTAGEOUS EFFECTS OF INVENTION 
     Compound II of the present invention exhibits favorable crystallinity, and is useful as a bulk pharmaceutical without problems in terms of moisture absorption and desorption characteristics, solubility, crystal stability, and chemical stability, compared with various other salts. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram showing the moisture absorption and desorption characteristics of the hydrobromide of compound A. The vertical axis shows weight change (%), and the horizontal axis shows relative humidity (%). The numeric value (%) in the upper central part of the diagram denotes weight change (%) between 40 and 60% relative humidities. 
         FIG. 2  is a diagram showing the moisture absorption and desorption characteristics of the hemisulfate of compound A. The vertical axis shows weight change (%), and the horizontal axis shows relative humidity (%). The numeric value (%) in the upper central part of the diagram denotes weight change (%) between 40 and 60% relative humidities. 
         FIG. 3  is a diagram showing the moisture absorption and desorption characteristics of the benzenesulfonate of compound A. The vertical axis shows weight change (%), and the horizontal axis shows relative humidity (%). The numeric value (%) in the upper central part of the diagram denotes weight change (%) between 40 and 60% relative humidities. 
         FIG. 4  is a diagram showing the moisture absorption and desorption characteristics of the citrate of compound A. The vertical axis shows weight change (%), and the horizontal axis shows relative humidity (%). The numeric value (%) in the upper central part of the diagram denotes weight change (%) between 40 and 60% relative humidities. 
         FIG. 5  is a diagram showing the moisture absorption and desorption characteristics of the (+)-tartrate of compound A. The vertical axis shows weight change (%), and the horizontal axis shows relative humidity (%). The numeric value (%) in the upper central part of the diagram denotes weight change (%) between 40 and 60% relative humidities. 
         FIG. 6  is a diagram showing the moisture absorption and desorption characteristics of the free form of compound A. The vertical axis shows weight change (%), and the horizontal axis shows relative humidity (%). The numeric value (%) in the upper central part of the diagram denotes weight change (%) between 40 and 60% relative humidities. 
         FIG. 7  is a diagram showing the moisture absorption and desorption characteristics of the nitrate of compound A. The vertical axis shows weight change (%), and the horizontal axis shows relative humidity (%). The numeric value (%) in the upper central part of the diagram denotes weight change (%) between 40 and 60% relative humidities. 
         FIG. 8  is a diagram showing the powder X-ray diffraction of the (+)-tartrate (Form I, Form II, and Form III) of compound A. The vertical axis shows relative intensity, and the horizontal axis shows diffraction angles (2θ). 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, Examples will be described. However, the present invention is not intended to be limited to them. 
     EXAMPLES 
     In the present Examples, the measurements of powder X-ray diffraction, thermal analysis (TG/DTA), and elemental analysis were performed under the following conditions. 
     Measurement conditions of powder X-ray diffraction (radiation source: Cu-Kα rays, filter: Ni, detector: scintillation counter, tube voltage: 35 kV, tube current: 20 mA, scanning rate: 0.025° 2θ/s, scanning range: 2θ=5°-40°, apparatus: Phillips X′Pert-MPD PW 3050) 
     Measurement conditions of thermal analysis (TG/DTA) (heating rate: 10° C./min., sample container: aluminum pan, reference material: vacant aluminum pan, atmosphere: 200 mL of nitrogen gas/min., sample volume: approximately 5 mg, apparatus: SEIKO Instruments Inc. SSC5200 TG/DTA 220) 
     Measurement conditions of elemental analysis (sample volume: approximately 2 mg, apparatus: CHNS analysis, type CHNS-932 elementary microanalyzer manufactured by LECO Corp., Cl analysis, COM-980win automatic titrator manufactured by Hiranuma Sangyo Corp.) 
     Reference Example 
     Compound A was synthesized according to a method described in Patent Literature 1 to 8. 
     Example 1 
     Salt Formation of Compound A and Evaluation of Crystallinity 
     (1) Synthesis of (+)-tartrate monohydrate of compound A (Form I) 
     409 mg of N 1 -(5-chloropyridin-2-yl)-N 2 -((1S,2R,4S)-4-[(dimethylamino)carbonyl]-2-{[(5-methyl-4,5,6,7-tetrahydrothiazolo[5,4-c]pyridin-2-yl)carbonyl]amino}cyclohexyl)ethanediamide (compound A) was dissolved in 20 mL of methylene chloride, and then an equimolar amount of a solution of (+)-tartaric acid in ethanol was added thereto. The solvent was distilled off to obtain a dry solid. To the dry solid, 31 mL of 30% aqueous ethanol was added, and the mixture was dissolved with heating and then left at room temperature. The deposited material was suction-filtered and then dried in air at room temperature to obtain the compound of interest (378 mg, yield: 71%). Form I was confirmed by powder X-ray diffraction. 
     Theoretical (in terms of monotartrate monohydrate): C, 46.96%; H, 5.35%; N, 13.69%; Cl, 4.95%; S, 4.48%. 
     Found: C, 46.80%; H, 5.11%; N, 13.73%; Cl, 5.08%; S 4.64%. 
     Form I had the following characteristic diffraction peaks in powder X-ray diffraction: 2θ=14.5, 17.2, 20.4, 21.3, 22.1, and 23.4°. 
     (2) Synthesis of (+)-tartrate monohydrate of compound A (Form II): Form II of the (+)-tartrate monohydrate of compound A was obtained in the same way as the synthesis of Form I in paragraph (1) except that 50% aqueous 2-propanol was added to the dried form. 
     Form II had the following characteristic diffraction peaks in powder X-ray diffraction: 2θ=13.9, 17.1, 17.7, 18.6, 21.3, 21.8, and 24.3°. 
     (3) Synthesis of (+)-tartrate monohydrate of compound A (Form III): Form III of the (+)-tartrate monohydrate of compound A was obtained in the same way as the synthesis of Form I in paragraph (1) except that 50% aqueous ethanol was added to the dried form. 
     Form III had the following characteristic diffraction peaks in powder X-ray diffraction: 2θ=13.9, 16.9, 17.5, 18.5, 21.4, and 22.1°. 
     (4) Salt formation of compound A was attempted using hydrobromic acid, sulfuric acid, methanesulfonic acid, benzenesulfonic acid, phosphoric acid, acetic acid, salicylic acid, maleic acid, lactic acid, malonic acid, succinic acid, citric acid, (−)-malic acid, and nitric acid, in addition to tartaric acid. Various salt formations were performed in the same way as the salt formation using tartaric acid. 
     As a result, the tartrate, hydrobromide, sulfate, methanesulfonate, benzenesulfonate, phosphate, citrate, and nitrate exhibited diffraction peaks in powder X-ray diffraction and were confirmed to be crystalline powders. 
     Example 2 
     Evaluation of Moisture Absorption and Desorption Characteristics 
     Various samples prepared in Example 1 were separately placed in quartz holders and measured for their moisture absorption and desorption behavior under the following conditions using a microbalance. 
     Moisture absorption and desorption behavior measurement conditions (sample volume: approximately 20 mg, measurement range: 10-90% RH, measurement temperature: 25° C., variable: within 0.03%, varying length of time: 10 min., apparatus: VTI atmospheric pressure-type automatic water vapor adsorption apparatus SGA-100) 
     The results are shown in  FIGS. 1 to 7 . 
     Compound A and the benzenesulfonate, citrate, nitrate, and tartrate of compound A had 1% or less weight change at 40% to 60% relative humidity. On the other hand, the hydrobromide of compound A exhibited generally favorable moisture absorption and desorption behavior, although its weight change exceeded 1%. 
     Example 3 
     Evaluation of Solubility 
     Solubility was evaluated as follows using various samples prepared in Example 1. A supersaturated amount of each sample was placed in a 12-mL test tube, and 3 mL of a test solution (water, Japanese Pharmacopoeia disintegration test solution No. 1 (JP1), and Japanese Pharmacopoeia disintegration test solution No. 2 (JP2)) was added thereto. The test tube was incubated in a constant-temperature water bath at 37° C. The test tube was shaken using a vortex mixer for 30 seconds every 5 minutes. 30 minutes later, the supernatant was filtered through a membrane filter (pore size: 0.45 μm), appropriately diluted with eluent, and then analyzed by HPLC under the following conditions. The concentration was calculated from a calibration curve prepared before measurement. 
     Measurement conditions of HPLC (column: Waters Symmetry C18 4.6 mm×150 mm, eluent: 0.05 M phosphate buffer (pH 5.0): acetonitrile=70:30, flow rate: 1 mL/min., detection: UV 220 nm, column temperature: 40° C.) 
     The results are shown in Table 1. 
     
       
         
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Water 
                 JP1 
                 JP2 
               
               
                   
                 (Solubility 
                 (Solubility 
                 (Solubility 
               
               
                   
                 (μg/mL)) 
                 (μg/mL)) 
                 (μg/mL)) 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Hydrobromide of 
                 &gt;2000 
                 &gt;2000 
                 99.2 
               
               
                   
                 compound A 
               
               
                   
                 (+)-Tartrate 
                 &gt;2000 
                 &gt;2000 
                 138 
               
               
                   
                 monohydrate of 
               
               
                   
                 compound A 
               
               
                   
                 Compound A 
                 47.5 
                 &gt;2000 
                 49.8 
               
               
                   
                   
               
             
          
         
       
     
     Example 4 
     Evaluation of Crystal Stability 
     Approximately 50 mg of each of various samples prepared in Example 1 was placed in a weighing bottle and stored at 25° C. in a desiccator whose relative humidity was adjusted to 0%, 52%, or 93% by a saturated salt solution method (silica gel, Mg(NO 3 ) 2 , KNO 3 ). After 3-day storage, the weight change was measured, and then the measurements of powder X-ray diffraction and thermal analysis (TG/DTA) were performed. 
     The results are shown in Table 2. 
     
       
         
               
               
               
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 2 
               
             
             
               
                   
                   
               
               
                   
                 0% RH 
                 52% RH 
                 93% RH 
               
             
          
           
               
                   
                   
                 Weight 
                   
                 Weight 
                   
                 Weight 
               
               
                   
                 Crystal 
                 change 
                 Crystal 
                 change 
                 Crystal 
                 change 
               
               
                   
                 form 
                 (%) 
                 form 
                 (%) 
                 form 
                 (%) 
               
               
                   
                   
               
             
          
           
               
                 Hydrobromide 
                 No 
                 −0.14 
                 No 
                 −0.13 
                 No 
                 10.22 
               
               
                 of compound A 
                 change 
                   
                 change 
                   
                 change 
               
               
                 (+)-Tartrate 
                 No 
                 −0.35 
                 No 
                 0.05 
                 No 
                 0.31 
               
               
                 monohydrate 
                 change 
                   
                 change 
                   
                 change 
               
               
                 of compound A 
               
               
                 Compound A 
                 No 
                 −0.32 
                 No 
                 −0.22 
                 No 
                 −0.04 
               
               
                   
                 change 
                   
                 change 
                   
                 change 
               
               
                   
               
             
          
         
       
     
     Example 5 
     Evaluation of Chemical Stability 
     Approximately 2 mg of each of various samples prepared in Example 1 was weighed into an aluminum pan for thermal analysis and stored under dry heat (50° C., 0% RH) or wet heat (40° C., 75% RH) conditions. 1 week or 2 weeks later, each sample was collected, and the weight change was measured. Then, the whole amount was dissolved in 20 mL of eluent and analyzed by HPLC. For photolysis samples, approximately 10 mg of each sample was weighed into a weighing bottle and stored at 25° C. in a light irradiator. After irradiation at 600,000 or 1,200,000 Lx/hr, the sample was collected, and the weight change was measured. Then, the whole amount was dissolved in 100 mL of eluent and analyzed by HPLC. The residue proportion was determined from the ratio between the concentration of the sample solution calculated from a calibration curve prepared before measurement and the theoretical concentration calculated from weight measurement. 
     Measurement conditions of HPLC (column: Waters Symmetry C18 4.6 mm×150 mm, eluent: 0.05 M phosphate buffer (pH 5.0): acetonitrile=80:20, flow rate: 1 mL/min., detection: UV 220 nm, column temperature: 40° C.) 
     The results are shown in Table 3. 
     
       
         
               
               
             
               
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 3 
               
             
             
               
                   
                   
               
               
                   
                 Residue (%, mean ± SD) 
               
             
          
           
               
                   
                 50° C., 0% RH 
                 40° C., 75% RH 
                 Light irradiation 
               
             
          
           
               
                   
                 1 week 
                 2 week 
                 1 week 
                 2 week 
                 (Lx · hr) 
               
             
          
           
               
                   
                 later 
                 later 
                 later 
                 later 
                 60 × 10 4   
                 120 × 10 4   
                 Color 
               
               
                   
               
               
                 (+)-Tartrate 
                 100.4 ± 0.7 
                 100.1 ± 0.7 
                 100.1 ± 0.7 
                 100.1 ± 0.3 
                 98.2 ± 0.9 
                 95.0 ± 1.2 
                 Slightly 
               
               
                 monohydrate 
                   
                   
                   
                   
                   
                   
                 changed 
               
               
                 of compound A 
               
               
                 Compound A 
                  99.3 ± 0.4 
                  97.5 ± 0.7 
                  99.8 ± 0.3 
                  98.7 ± 1.3 
                 92.0 ± 0.3 
                 82.8 ± 0.4 
                 Changed