AU700976B2 - Novel polymorphic forms of troglitazone having enhanced anti-diabetic activity and a process for their preparation - Google Patents

Description

WO 97/27191 PCT/US97/02577 NOVEL POLYMORPHIC FORMS OF TROGLITAZONE HAVING ENHANCED ANTI-DIABETIC ACTIVITY AND A PROCESS FOR THEIR PREPARATION BACKGROUND OF THE INVENTION This invention relates to a discovery of the preparation of novel polymorphic/pseudopolymorphic forms of Troglitazone and process for the preparation of various polymorphic/pseudopolymorphic forms of Troglitazone. Troglitazone is 5-[[4-[3(3,4-dihydro-6hydroxy-2,5,7,8-tetramethyl-2H-l-benzopyran-2-yl) methoxy] phenyl] methyl] 2,4-thiazolidinedione, having the Formula I shown below. The polymorphic forms prepared by the process of the present invention are more active, as an antidiabetic agent, than the hitherto known Troglitazone.

O

o Out of the many drugs available for the treatment of diabetic ailments, the thiazolidinedione derivatives are very prominent and are considered as WO 97/27191 PCT/US97/02577 2 much superior effective-constituents compared to the sulphonyl ureas. Troglitazone, one such thiazolidinedione, which exhibited euglycemic effect, was reported in the year 1983 by Sankyo Co. Ltd., Japan (Japanese Patent No. 60-051189/Australian Patent No. 570067) and created interest in the field, ever since.

Previously, the oral diabetic medicines consisting of sulphonyl urea were believed to be effective in bringing down the sugar level in blood (Hypoglycemic) but they lacked efficiency in preventing/reducing diabetes related complications like cataract, nervous break down, retinopathia etc. (which are usually the chronic ailments accompanied by diabetes). Aldose reductase is the enzyme which reduces aldose present in the humans and animals into corresponding polyols which, in turn, are stored or accumulated in the kidneys, peripheral nerves, eye lens of the diabetic patients and manifest themselves in the above mentioned complications.

With a view to prevent/cure the chronic complications of diabetes, research is being conducted round the world in recent times. Troglitazone hitherto known is being considered today as one of the most effective antidiabetic drugs which has a multipurpose activity not only acting on diabetes itself but also on the reduction of the triglycerides and also on the accompanying complications mentioned above. Indeed, the said Troglitazone is emerging as the first drug candidate of euglycemic class of antidiabetic agents.

The latest trend that has, of late, crept into the pharmaceutical industry is the studies on polymorphism in drugs and the difference in the activity of different polymorphic forms of a given drug. By the term polymorphism we mean to include different physical forms, crystal forms, crystalline/ liquid crystalline/non-crystalline (amorphous) forms.

WO 97/27191 PCT/US97/02577 3 This has especially become very interesting after observing that many antibiotics, antibacterials, tranquilizers etc., exhibit polymorphism and some/one of the polymorphic forms of a given drug exhibit superior bio-availability and consequently show much higher activity compared to other polymorphs.

Sertraline, Frentizole, Ranitidine, Sulfathiazole, Indomethacine etc. are some of the important examples of pharmaceuticals which exhibit polymorphism.

SUMMARY OF THE INVENTION Sankyo Co. Ltd, Japan states in its annual report (Annu. Rep. Sankyo. Res. lab., 46, pp. 1-57, 1994) that the relative configurations of the diastereomers have been determined by X-ray crystallographic analysis and that the crystal and molecular structure of Troglitazone is under preparation. The report does not touch upon the possibility/observation that Troglitazone exists in different polymorphic forms. There is no published literature regarding such an observation till date.

Polymorphism in drugs is a topic of current interest and is evident from the host of patents being granted.

To cite a few, U.S. 5,248,699 discusses about five polymorphic forms of Sertraline hydrochloride while EP 014590 describes four polymorphic forms of Frentizole.

EP 490648 and EP 022527 also deal with the subject of polymorphism in drugs. The fact that polymorphism in Troglitazone has not been studied earlier coupled with the current interest in the field of polymorphism in drugs prompted us to take up this investigation. Our observations and results form the subject matter of the present invention.

We have, due to our sustained research directed towards finding out effective antidiabetic drugs, observed that Troglitazone can be prepared in different polymorphic forms possessing anti-diabetic activity. We have, in the course of research, prepared WO 97/27191 PCT/US97/02577 4 and studied at least six polymorphic forms of Troglitazone. These polymorphs have been designated, by us, as Forms 1,2,3,4,5 6.

Our present invention relates to an observation that Troglitazone exhibits polymorphism, which has not been reported till date. Polymorphic Forms 1,2,3 and 6 are obtained by different modes of recrystallization while the polymorphic Forms 4 and are derived from melting/heating any of the polymorphic Forms 1,2,3 and 6. A slow recrystallization of the crude Troglitazone gives the polymorphic Form-l. On the other hand, a fast recrystallization of the same crude Troglitazone gives the polymorphic Form-2. This Form-2 of 99% High Pressure Liquid Chromatography (HPLC) purity upon slow recrystallization gives the polymorphic Form-3. Polymorphic Forms 1,2,3 and 6 when melted, produce a glossy/transparent material which on thorough grinding gives a fine powder. This pale yellow powder does not give any peaks due to X-Ray Diffraction (XRD). This could be amorphous/liquid crystalline in nature. This amorphous/liquid crystalline form is designated as Form-4.

Interestingly, the non-crystalline Form-4 on isothermal heating at 130°C. yields the crystalline form, designated as Form All these polymorphic forms were proved to be identical in solution as evident from Nuclear Magnetic Resonance (NMR), Ultra Violet (UV) Mass spectral data. On the other hand, solid state techniques like Differential Scanning Calorimetry (DSC), Powder X-Ray Diffractometry (XRD) and Infra Red spectroscopy (IR) revealed the difference among these forms.

DSC of the polymorphic Form-1 and polymorphic Form-3 have one melting endotherm each at -180 0 C. and ~186*C. (Figs. 1 2 respectively.

Polymorphic Form-2 exhibits an endotherm, in the temperature region 110-120°C. (hereafter referred as WO 97/27191 PCT/US97/02577 5 Peak 1) before the melting endotherm in the region 165- 190 0 C. as shown in Fig-3. It was also observed that when the polymorphic Form-2 is heated to 150 0 C. and cooled, the rerecorded DSC thermogram showed the reduction and absence of the peak 1 as represented by Figs. 4 5 respectively, indicating the conversion of the polymorphic Form-2 into another polymorphic form completely/partially. It was confirmed by Thermo Gravimetry (TG) Mass spectroscopic studies that the Peak 1 present in polymorphic Form-2 is not due to any volatile material as there was no weight loss in TG and no mass was detected by analyzing the evolved gases from TG, using mass spectrometry. However, the possibility of mixture of polymorphs constituting this polymorphic Form-2 can not be ruled out.

Interestingly, DSC studies on polymorphic Form-4 exhibited (Fig. 6) a small endotherm at ~57 0 an exotherm at -100-130°C. and a melting endotherm at -1770C. The endotherm at 57°C. could be because of phase transition/loss of some volatile material. The exotherm at -100-1300C. is due to crystallization while the endotherm at -177 0 C. is due to melting. Hence, in principle, if the amorphous/liquid crystalline polymorphic Form-4 when heated at -130°C., should result in a crystalline form. It is reasonable to expect the amorphous/liquid crystalline polymorphic Form-4 to acquire crystallinity when heated at -130°C.

Indeed, when the polymorphic Form-4 was heated at 130°C., it attained crystallinity and the DSC of this material exhibited only the melting endotherm (Fig. 7) at -177°C., indicating the absence of phase transition and the disappearance of liquid crystalline nature.

The new crystalline form thus obtained is designated as polymorphic Form 5. The DSC study also reveals that the polymorphic Form-4 is not only noncrystalline/ liquid crystalline but also metastable in nature. The plausible reason for the enhanced activity of the WO 97/27191 PCT/US97/02577 6 polymorphic Form-4 may be due to the thermodynamically less stable nature of noncrystalline/liquid crystalline form. The polymorphic Form-6 exhibits a single melting endotherm at ~105°C. (Fig. 8).

The XRD of the crystalline polymorphic Forms 1,2,3,5 6 were found to be different from each other (Figs. 9-13) while the polymorphic Form-4 showed no XRD pattern confirming its amorphous/liquid crystalline nature as shown in the (Fig. 14). Fig. 15 gives the powder X-ray diffraction pattern of the Forms 1,2,3,5 and 6 to facilitate easy comparison.

The Infrared absorption spectra of Forms 1 to 6 in potassium bromide are different from one another which become apparent only after closer examination.

The spectra are depicted in Figs. 16-21 respectively.

The overlapped IR spectra of all the Forms 1 6 (Fig.

22) and the sectional expansions (Figs. 23-26) are also provided. A qualitative comparison of such spectra, (Figs. 22-26) reveals the following differences.

a. Forms 2 6 exhibit absorption bands of medium intensity at -3650 cm 1 while no absorption is observed for the others (Fig. 23).

b. Form 1 exhibits a strong absorption with a shoulder at -3450 cm while Forms 3 5 absorb without a shoulder. On the other hand Form 2 exhibits a band at -3550 cm while Form 4 has it at -3500 cm (Fig. 23).

c. Forms 1 2 have a weak absorption at -1 -3300 cm Form 3 has a strong band while no absorption for the rest (Fig. 23).

d. Forms 1 3 have a strong absorption at -I

-I

-2980 cm with a shoulder at -2925 cm while Forms 2, 4 and 5 show only a weak peak at -2980 cm I with no shoulder. Form 6 shows no absorption in this region (Fig. 23).

e. All the forms, show absorption -1750 cm-1 and 1700 cm. Only Form 5 shows a shoulder in both and -1700 cm Only Form 5 shows a shoulder in both WO 97/27191 PCT/US97/02577 7 these wavenumbers while Form 1 has a shoulder in the latter (Fig. 24).

f. Forms 2 6 have a strong peak at ~1255 -i -l cm while the rest have it at -1240 cm (Fig. g. Form 3 has a weak absorption at -700 cm-1 while others have no absorption. (Fig. 26).

h. Form 6 exhibits three weak absorption bands while the others have negligible absorption (Fig. 26).

BRIEF DESCRIPTION OF THE FIGURES Fig. 1 is a characteristic differential scanning calorimetric thermogram of Form 1.

Fig. 2 is a characteristic differential scanning calorimetric thermogram of Form 3.

Fig. 3 is a characteristic differential scanning calorimetric thermogram of Form 2.

Fig. 4 is a characteristic differential scanning calorimetric thermogram of Form 2 showing the reduction of peak 1 after heating.

Fig. 5 is a characteristic differential scanning calorimetric thermogram of Form 2 showing the absence of peak 1 after heating.

Fig. 6 is a characteristic differential scanning calorimetric thermogram of Form 4.

Fig. 7 is a characteristic differential scanning calorimetric thermogram of Form Fig. 8 is a characteristic differential scanning calorimetric thermogram of Form 6.

Fig. 9 is a characteristic X-ray powder diffraction pattern of Form 1.

Fig. 10 is a characteristic X-ray powder diffraction pattern of Form 2.

Fig. 11 is a characteristic X-ray powder diffraction pattern of Form 3.

Fig. 12 is a characteristic X-ray powder diffraction pattern of Form Fig. 13 is a characteristic X-ray powder WO 97/27191 PCT/US97/02577 8 diffraction pattern of Form 6.

Fig. 14 is a characteristic X-ray powder diffraction pattern of Form 4.

Fig. 15 is the multi-plot of X-ray powder diffraction patterns of Forms 1,2,3,5,6.

Fig. 16 is a absorption spectrum of bromide).(KBr).

Fig. 17 is a absorption spectrum of Fig. 18 is a absorption spectrum of Fig. 19 is a absorption spectrum of Fig. 20 is a absorption spectrum of Fig. 21 is a absorption spectrum of characteristic infrared Form 1 in potassium characteristic Form 2 in KBr.

characteristic Form 3 in KBr.

characteristic Form 4 in KBr.

characteristic Form 5 in KBr.

characteristic Form 6 in KBr.

infrared infrared infrared infrared infrared Fig.22 is the multi-plot of infrared absorption spectra of Forms 1,2,3,4,5,6 (4000-500 cm- 1 Common color code for Figs. 22-26: Black 1; Orange Form 2; Red Form 3; Violet Form 4; Blue Form 5; Green Form 6.

Fig. 23 is the multi-plot of infrared absorption spectra of Forms 1,2,3,4,5,6 (3800-2400 cm-1.

cm Form Fig. 24 is the multi-plot of infrared absorption spectra of Forms 1,2,3,4,5,6 (1800-1500 m-l cm Fig. 25 is the multi-plot of infrared absorption spectra of Forms 1,2,3,4,5,6 (1500-1100 cm- 1 Fig. 26 is the multi-plot of infrared absorption spectra of Forms 1,2,3,4,5,6 (1125-500 cm 1 DETAILED DESCRIPTION OF THE INVENTION Accordingly, the present invention provides a 9 process for the preparation of novel polymorphic Form-i of Troglitazone having the Formula I shown in the drawing accompanying this specification which comprises synthesizing Troglitazone, in crude form employing known methods, (ii) subjecting the crude Troglitazone obtained in step to column chromatography to obtain a partially purified Troglitazone having HPLC purity in the range of 60-70%, (iii) dissolving the partially purified Troglitazone obtained in step (ii) in an organic polar and/or medium polar solvent and heating the resulting solution with a non-polar solvent and (iv) cooling the resulting solution slowly 15 to room temperature at a rate of 0.1 to over a period in the range of 24-72 h to produce the polymorphic Form-i of Troglitazone which is characterized by the following data.

DSC: Endotherm at 179.3°C. (onset at 20 169.3 0 (Fig. 1) X-ray powder diffraction 5.56, 11.10, 11.66, 15.72, 16.62, 17.62, 18.24, 19.70, 21.20, 21.42, 23.40, 23.70, (Fig. 9) -1 Infrared absorption bands (cm 3442(w), 3218(w), 2921(w), 1748(m), 1686(s), 1610(w), 1582(w), 1513(s), 1454(w), 1420(w), 1382(w), 1302(m), 1244(s), 1169(m), 1118(w), 1086(w), 1048(m), 931(w), 863(w), 827(w), 798(w), 720(w), 509(w). (Fig. 16) w weak, m medium, s strong According to another feature of the invention, there is provided a process for the preparation of novel polymorphic Form-2 of Troglitazone having the Formula I which comprises synthesizing Troglitazone, in crude form employing known methods, (ii) subjecting the crude Troglitazone obtained in step to column chromatography to obtain 10 a partially purified Troglitazone having HPLC purity in the range of 60-70%, (iii) dissolving the partially purified Troglitazone obtained in step (ii) in an organic polar and/or medium polar solvent and heating the resulting solution with a non-polar solvent, and (iv) scratching the resulting solution, while cooling rapidly to a temperature between 0 to 0 C. at a rate of 2 to 10 0 C./minute over a period in the range of 10-30 min. to precipitate the polymorphic Form-2 of Troglitazone which is characterized by the e9", following data.

DSC: Endotherms at 110.1 0 C. (onset at 102.4 0 and at 175.1 0 C. (onset at 155.9 0 (Fig. 3) 15 X-ray powder.diffraction 5.42, 10.24, S10.72, 11.58, 11.72, 15.60, 17.56, 18.16, 19.48, 19.58, 19.68, 21.44, 22.20, 23.28, 23.66, 24.14, 24.38, (Fig.

Infrared absorption bands (cm 3506(w), 20 3187(w), 3061(w), 2931(w), 1751(m), 1688(s), 1610(w), 1583(w), 1512(s), 1454(w), 1419(w), 1381(w), 1334(w), 1301(m), 1252(s), 1165(m), 1088(w), 1047(w), 932(w), 828(w), 722(w), 511(w) (Fig. 17) w weak, m medium, s strong According to yet another embodiment of the present invention, there is provided a process for the preparation of a novel polymorphic Form-3 of Troglitazone, having the Formula I, which comprises synthesizing Troglitazone, in crude form employing known methods, (ii) subjecting the crude Troglitazone obtained in step to column chromatography to obtain a partially purified Troglitazone having HPLC purity in the range of 60-70%, (iii) dissolving the partially purified Troglitazone obtained in step (ii) in an organic polar 11 and/or medium polar solvent and heating the resulting solution with a non-polar solvent, and (iv) scratching the resulting solution, while cooling rapidly to a temperature between 0 to -20°C. at a rate of 2 to 100C./minute over a period in the range of 10-30 min. to precipitate the polymorphic Form-2 of Troglitazone.

dissolving the polymorphic Form-2 of Troglitazone so obtained in step (iv) in an organic polar and/or medium polar solvent and heating the 0:40 resulting solution with a non-polar solvent on a steam bath, and (vi) cooling the solution slowly to room temperature at a rate of 0.1 to 1C./minute over a S 15 period in the range of.24-72 h to crystallize the polymorphic Form-3 of Troglitazone which is A b characterized by the following data.

DSC: Endotherm at 185.8 0 C. (onset at 175.4 0 (Fig. 2) S 20 X-ray powder diffraction 5.44, 11.74, 13.24, 15.62, 16.02, 17.56, 18.12, 19.65, 21.41, 23.00, 23.31, 23.65, 24.43, 26.51. (Fig. 11) -1 Infrared absorption bands (cm 3439(w), 3295(w), 2972(w), 2932(w) 1747(m), 1690(s), 1611(w), 1582(w), 1512(s), 1453(m), 1384(w), 1302(m), 1245(s), 1221(s), 1169(s), 1143(w), 1119(w), 1089(w), 1049(w), 931(w), 828(w), 722(w), 510(w) (Fig. 18) w weak, m medium, s strong According to yet another embodiment of the present invention, there is provided a process for the preparation of a novel polymorphic Form-4 of Troglitazone, having the Formula I, which comprises synthesizing Troglitazone, in crude form employing known methods, (ii) subjecting the crude Troglitazone obtained in step to column chromatography to obtain a partially purified Troglitazone having HPLC purity in WO 97/27191 PCT/US97/02577 12 the range of 60-70%, (iii) dissolving the partially purified Troglitazone obtained in step (ii) in an organic polar and/or medium polar solvent and heating the resulting solution with a non-polar solvent, (iv) cooling the resulting solution slowly to room temperature at a rate of 0.1 to 1 0 C./minute over a period in the range of 24-72 h to produce the polymorphic Form-1 of Troglitazone, filtering the product and melting it by heating, (vi) cooling the melt to ambient temperature slowly at a rate of 0.1 to 1*C./minute over a period in the range of 1-4 h to give a glossy transparent material, (vii) grinding the transparent flake to a fine powder to yield the polymorphic Form-4 of Troglitazone which is characterized by the following data.

DSC: Endotherm at 56.6 0 exotherm at 110.4 0 C. (onset at 93.6 0 and endotherm 177.1 0

C.

(onset at 153.7 0 (Fig. 6) X-ray powder diffraction No diffraction peaks due to its amorphous nature (Fig. 14) Infrared absorption bands (cm 3473(w), 3204(w), 3060(w), 2924(w), 1754(m), 1696(s), 1610(w), 1583(w), 1512(s), 1457(m), 1420(w), 1378(w), 1333(m), 1301(m), 1243(s), 1162(m), 1115(w), 1085(w), 1041(w), 928(w), 849(w), 827(w), 715(w), 664(w), 512(w) (Fig.

19) w weak, m medium, s strong According to yet another embodiment of the present invention, there is provided a process for the preparation of the novel polymorphic Form-4 of Troglitazone, having the Formula I, which comprises synthesizing Troglitazone, in crude form employing known methods, WO 97/27191 PCT[US97/02577 13 (ii) subjecting the crude Troglitazone obtained in step to column chromatography to obtain a partially purified Troglitazone having HPLC purity in the range of 60-70%, (iii) dissolving the partially purified Troglitazone obtained in step (ii) in an organic polar and/or medium polar solvent and heating the resulting solution with a non-polar solvent, (iv) scratching while cooling.rapidly to a temperature in the range of 0 to -20 0 C. at a rate of 2 to 10°C./minute, over a period in the range of 10-30 min. to precipitate the polymorphic Form-2 of Troglitazone, filtering the product and melting it by heating, (vi) cooling the melt to ambient temperature slowly at a rate of 0.1 to 1 0 C./minute over a period in the range of 1-4 h to give a glossy transparent material, (vii) grinding the transparent flake to a fine powder to yield the polymorphic Form-4 of Troglitazone which is characterized by the data presented in the previous method.

According to yet another embodiment of the present invention, there is provided a process for the preparation of the novel polymorphic Form-4 of Troglitazone, having the Formula I, which comprises synthesizing Troglitazone, in crude form employing known methods, (ii) subjecting the crude Troglitazone obtained in step to column chromatography to obtain a partially purified Troglitazone having HPLC purity in the range of 60-70%, (iii) dissolving the partially purified Troglitazone obtained in step (ii) in an organic polar and/or medium polar solvent and heating the resulting solution with a non-polar solvent, 14 (iv) scratching the resulting solution, while cooling rapidly to a temperature in the range of 0 to -20 0 C. at a rate of 2 to 10 0 C./minute, over a period in the range of 10-30 min. to precipitate the polymorphic Form-2 of Troglitazone, dissolving the polymorphic Form-2 of Troglitazone so obtained in step in an organic polar and/or medium polar solvent and heating the resulting solution with a non-polar solvent preferably on steam bath, (vi) cooling the solution slowly to room

U.

temperature at a rate of 0.1 to 1C./minute, over a period in the range of 24-72 h to crystallize the polymorphic Form-3 of Troglitazone, 15 (vii) filtering the product and melting it by heating, (viii) cooling the melt to ambient temperature slowly at a rate of 0.1 to 1 0 C./minute, over a period in the range of 1-4 h to give a glossy 20 transparent material o* (ix) grinding the transparent flake to a fine powder to yield the polymorphic Form-4 of oo* Troglitazone which is characterized by the data presented in the previous method.

25 According to a further embodiment of the present invention, there is provided a process for the preparation of a novel polymorphic Form-5 of Troglitazone having the Formula I, which comprises synthesizing Troglitazone, in crude form employing known methods, (ii) subjecting the crude Troglitazone obtained in step to column chromatography to obtain a partially purified Troglitazone having HPLC purity in the range of 60-70%, (iii) dissolving the partially purified Troglitazone obtained in step (ii) in an organic polar and/or medium polar solvent and heating the resulting 15 solution with a non-polar solvent, (iv) cooling the resulting solution slowly to room temperature at a rate of 0.1 to 1lC./minute, over a period in the range of 24-72 h to produce the polymorphic Form-1 of Troglitazone, filtering the product and melting it by heating, (vi) cooling the melt to ambient temperature at a rate of 0.1 to 1 0 C./minute over a period in the range of 1-4 h to give a glossy transparent material, (vii) grinding the transparent flake to a fine powder to yield the polymorphic Form-4 of Troglitazone, (viii) subjecting the polymorphic Form-4 of 15 Troglitazone so obtained in step (vii) to isothermal heating in the range of 60 to 170 0 C. preferably at 130 0 for a period in the range of 5 min. to 4 h, cooling to ambient temperature slowly at a rate of 0.1 to 1 0 C./minute, over a period in the range of 1-4 h, 20 followed by grinding the flake to a fine powder to yield the polymorphic Form 5 of Troglitazone which is characterized by the following data.

DSC: Endotherm at 180.5 0 C. (onset at 157.9 0 (Fig. 7) X-ray powder diffraction 5.60, 11.06, 11.62, 15.48, 15.78, 16.48, 18.12, 18.34, 21.06, 21.90, 23.34, 23.58 (Fig. 12) Infrared absorption bands (cm 3462(w), 3211(w), 3060(w), 2921(w) 1756(m), 1685(s), 1610(w), 1583(w), 1513(s), 1454(m), 1419(w), 1381(w), 1303(m), 1244(s), 1168(m), 1117(w), 1085(w), 1047(m), 929(w), 861(w), 825(w), 718(w), 665(w), 564(w), 509(w) (Fig.

w weak, m medium, s strong According to a further embodiment of the present invention, there is provided a process for the Spreparation of a novel polymorphic Form-5 of WO 97/27191 PCT/US97/02577 16 Troglitazone having the Formula I, which comprises synthesizing Troglitazone, in crude form employing known methods, (ii) subjecting the crude Troglitazone obtained in step to column chromatography to obtain a partially purified Troglitazone having HPLC purity in the range of 60-70%, (iii) dissolving the partially purified Troglitazone obtained in step (ii) in an organic polar and/or medium polar solvent and heating the resulting solution with a non-polar solvent, (iv) scratching while cooling rapidly to a temperature in the range of 0 to -20 0 C. at a rate of 2 to 10 0 C./minute, over a period in the range of 10-30 min. to precipitate the polymorphic Form-2 of Troglitazone, filtering the product and melting it by heating, (vi) cooling the melt to ambient temperature slowly at a rate of 0.1 to 1 0 C./minute, over a period in the range of 1-4 h to give a glossy transparent material, (vii) grinding the transparent flake to a fine powder to yield the polymorphic Form-4 of Troglitazone, (viii) subjecting the polymorphic Form-4 of Troglitazone so obtained in step (vii) to isothermal heating in the range of 60 to 170 0 C. preferably at 130°C. for a period in the range of 5 min. to 4 h, cooling to ambient temperature at a rate of 0.1 to 1 0 C./minute, over a period in the range of 1-4 h followed by grinding the flake to a fine powder to yield the polymorphic Form-5 of Troglitazone which is characterized by the data presented in the previous method.

According to a further embodiment of the present invention, there is provided a process for the 17 preparation of a novel polymorphic Form-5 of Troglitazone having the Formula I, which comprises synthesizing Troglitazone, in crude form employing known methods, (ii) subjecting the crude Troglitazone obtained in step to column chromatography to obtain a partially purified Troglitazone having HPLC purity in the range of 60-70%, (iii) dissolving the partially purified Troglitazone obtained in step (ii) in an organic polar and/or medium polar solvent and heating the resulting solution with a non-polar solvent, (iv) scratching the resulting solution, while cooling rapidly to a temperature in the range of 0 to -20 0 C. at a rate of 2-100C./minute, over a period S* in the range of 10-30 min. to precipitate the polymorphic Form-2 of Troglitazone, dissolving the polymorphic Form-2 of Troglitazone so obtained in step (iv) in an organic 20 polar and/or medium polar solvent and heating the S.resulting solution with a non-polar solvent preferably on a steam bath, (vi) cooling the solution slowly to room temperature at a rate of 0.1 to 10C./minute, over a period in the range of 24-72 h to crystallize the polymorphic Form-3 of Troglitazone, (vii) filtering the product and melting it by heating, (viii) cooling the melt to ambient temperature at a rate of 0.1 to 1 0 C./minute, over a period in the range of 1-4 h to give a glossy transparent material, (ix) grinding the transparent flake to a fine powder to yield the polymorphic Form-4 of Troglitazone, subjecting the polymorphic Form-4 of Troglitazone obtained in step (ix) to isothermal u 18 heating in the range of 60 to 170C. preferably at 130°C. for a period in the range of 5 min. to 4 h, cooling to ambient temperature slowly at a rate of 0.1 to 1 0 C./minute, over a period in the range of 1-4 h followed by grinding the flake to a fine powder to yield the polymorphic Form-5 of Troglitazone which is characterized by the data presented in the previous method.

According to yet another embodiment of the present invention there is provided a process for the preparation of novel polymorphic Form-6 of Troglitazone having the Formula I which comprises synthesizing Troglitazone, in crude form employing known methods, (ii) subjecting the crude Troglitazone obtained in step to column chromatography to obtain a partially purified Troglitazone having HPLC purity in the range of 60-70%, (iii) dissolving the partially purified 20 Troglitazone obtained in step (ii) in an organic polar and/or medium polar solvent and adding a non-polar solvent to the resulting solution and t (iv) cooling the resulting solution rapidly •to ~5 0 C. at a rate of 10°C./minute and maintaining the 25 temperature at for a period of 10-16 h to produce the polymorphic Form-6 of Troglitazone which is •characterized by the following data.

DSC: Endotherm at 105.4 0 C. (onset at 94.8 0 (Fig. 8) X-ray powder diffraction 5.36, 8.54, 10.24, 10.70, 11.24, 12.48, 12.68, 15.58, 18.84, 19.48, 19.74, 20.58, 21.38, 21.56, 22.18, (Fig. 13) Infrared absorption bands (cm- 3634(w), 3514(w), 3176(w), 3060(w), 2930(w), 1753(m), 1686(s), 1610(w), 1512(s), 1459(w), 1418(w), 1380(w), 1335(m), WO 97/27191 PCT/US97/02577 19 1300(m), 1253(s), 1164(s), 1106(w), 1087(w), 1058(w), 1048(w), 937(w), 828(m), 723(w), 673(w), 606(w), 568(w), 515(w) (Fig. 21) w weak, m medium, s strong According to yet another embodiment of the present invention, there is provided a process for the preparation of the novel polymorphic Form-4 of Troglitazone, having the Formula I, which comprises melting the polymorphic Form-5 of Troglitazone prepared by any one of the processes described above, by heating.

(ii) cooling the melt to ambient temperature slowly at a rate of 0.1 to 1 0 C./minute, over a period in the range of 1-4 h to give a glossy transparent material, (iii) grinding the transparent flake to a fine powder to yield the polymorphic Form-4 of Troglitazone which is characterized by the data presented earlier.

According to yet another embodiment of the present invention, there is provided a process for the preparation of the novel polymorphic Form-4 of Troglitazone, having the Formula I, which comprises melting the polymorphic Form-6 of Troglitazone prepared by the process described above, by heating.

(ii) cooling the melt to ambient temperature slowly at a rate of 0.1 to 1*C./minute, over a period in the range of 1-4 h to give a glossy transparent material, (iii) grinding the transparent flake to a fine powder to yield the polymorphic Form-4 of Troglitazone which is characterized by the data presented earlier.

According to yet another embodiment of the present invention, there is provided a process for the preparation of the novel polymorphic Form-5 of WO 97/27191 PCT/US97/02577 20 Troglitazone, having the Formula I, which comprises melting the polymorphic Form-6 of Troglitazone prepared by the process described above, by heating.

(ii) cooling the melt to ambient temperature slowly at a rate of 0.1 to l1C./minute, over a period in the range of 1-4 h to give a glossy transparent material.

(iii) grinding the transparent flake to a fine powder to yield the polymorphic Form-4 of Troglitazone.

(iv) subjecting the polymorphic Form-4 of Troglitazone obtained in step (iii) to isothermal heating in the range of 60 to 170*C. preferably at 130 0 C. for a period in the range of 5 min. to 4 h, cooling to ambient temperature slowly at a rate of 0.1 to 1 0 C./minute, over a period in the range of 1-4 h followed by grinding the flake to a fine powder to yield the polymorphic Form-5 of Troglitazone which is characterized by the data presented in the previous method.

The organic polar and/or medium polar solvents are selected from acetonitrile, ethanol, methanol, acetone, 1,4-dioxane, methyl ethyl ketone, ethylacetate, chloroform, tetrahydrofuran, n-propanol, isopropanol, 1,2-dichloroethane, dichloromethane, diethylether, benzene, etc. while the non-polar solvents are selected from hexane, heptane, cyclohexane, carbontetrachloride, toluene, xylene, etc.

The present invention is described in detail with examples given below that are provided by way of illustration only and therefore should not be construed to limit the scope of the invention.

Process for the preparation of crude Troglitazone of -70% HPLC purity, the starting material for the preparation of novel polymorphic forms according to the present invention WO 97/27191 PCT/US97/02577 21 Example-1: A mixture of 70 g of ethyl-3-[4-(6-acetoxy- 2,5,7,8-tetramethylchroman-2-yl-methoxy)phenyl]-2chloropropionate, 13.12 g of thiourea and 80.2 ml of sulpholane was reacted for 80 min., under a nitrogen stream at 115-120°C. Subsequently, a 656.2 ml Acetic acid, 218.7 ml cone. hydrochloric acid and 109.4 ml water was added to this and the resulting mixture was further heated for 12 hrs at 85-90 0 C. The reaction mixture was cooled to room temperature and 196.8 g of sodium bicarbonate was added and once the evolution of carbondioxide had ceased, the solvent was distilled off applying high vacuum. A 10:1 by volume mixture of benzene and ethyl acetate was added to the residue and the crude product was washed with a mixture of equal volumes of a saturated aq. sodium bicarbonate solution water. The organic layer was dried over anhydrous sodium sulphate and the solvent was distilled off. The resulting crude product was quickly eluted from a silica gel column with 50% ethylacetate-hexane to furnish 40 g of the required 5-{(4-(6-hydroxy-2, 5, 7, 8-tetramethylchroman-2-yl-methoxy) benzyl) thiazolidine-2,4-dione (Troglitazone) with a HPLC purity of -67-70%. The elution of column was continued further to yield 5-[4-(6-hydroxy-2,5,7,8tetramethylchroman-2-yl-methoxy)benzyl]2iminothiazolidine-4-one with HPLC purity of Examples 2-4 illustrate the process for the preparation of the polymorphic Form-1 of Troglitazone Example-2: g of the crude Troglitazone obtained by the process as described in Example-i was adsorbed on 60-120 mesh silica gel and extracted first with hexane using a soxhlet and then with benzene. Hexane extract mostly contained the less polar impurities while the benzene extract contained the required product. The benzene extract was concentrated and dried so as to WO 97/27191 PCT/US97/02577 22 remove traces of benzene. The gummy material was taken up in dichloromethane and stirred vigorously to obtain a clear solution. The solution was allowed to stand at room temperature for a period of 48 hrs to yield 40 g of 99% pure polymorphic Form-I of Troglitazone.

Example-3: 15.5 g of 5-[4(6-hydroxy-2,5,7,8-tetramethyl chroman-2-yl-methoxy) benzyl]-2-iminothiazolidine-4one, prepared by the process as described in Example- 1, was added to a mixture of 225 ml of acetic acid, ml of cone. hydrochloric acid and 40 ml of water and the mixture was refluxed for 12 hrs. The reaction mixture was cooled to room temperature and 66.2 g of sodium bicarbonate was added and once the evolution of carbondioxide had ceased, the solvent was distilled off applying high vacuum. A 10:1 by volume mixture of benzene and ethyl acetate was added to the residue and the crude product was washed with a mixture of equal volumes of a saturated aq. sodium bicarbonate solution water. The organic layer was dried over anhydrous sodium sulphate and the solvent was distilled off. The resulting crude product was quickly eluted from a silica gel column with 50% ethylacetate-hexane to finish 12.5 g of the required 5-{4-(6-hydro-2, 5, 7, 8tetramethylchroman-2yl-methoxy) benzyl) thiazolidine- 2,4-dione (Troglitazone) with a HPLC purity of -67-70%.

g of crude Troglitazone so obtained was taken in Iml of acetone and -100 ml benzene was added and heated on a steam bath till the solid dissolved completely. The clear solution was filtered and allowed to cool to room temperature at a rate of 0.1 to over a period of 48 h to yield 2.5 g of 99% pure polymorphic Form-1 of Troglitazone.

Example-4: 5 g of crude Troglitazone obtained by the process as described in Example-i was taken in -100 ml benzene and heated on steam bath till the solid WO 97/27191 PCT/US97/02577 23 completely dissolved and the clear solution was allowed to cool to room temperature at a rate of 0.1 to 1 0 C./minute during a period 36 h to give 2.5 g of 99% pure polymorphic Form-1 of Troglitazone.

Examples 5-8 illustrate the process for the preparation of the polymorphic Form-2 of Troglitazone g of the crude Troglitazone obtained by the process as described in Example-i was adsorbed on 60-120 mesh silica gel and extracted first with hexane using a soxhlet and then with benzene. Hexane extract mostly contained the less polar impurities while the benzene extract contained the required product. The benzene extract was concentrated and dried so as to remove traces of benzene. The gummy material was taken up in dichloromethane and stirred vigorously to obtain a clear solution. The solution was rapidly cooled to 0 at a rate of 10 0 C./minute, over a period of min. while scratching to field 40 g of 99% pure polymorphic Form-2 of Troglitazone.

Example-6: 15.5 g of 5[ 4 -(6-hydroxy-2,5,7,8-tetramethyl chroman-2-yl-methoxy) benzyl)-2-iminothiazolidine-4one, prepared by the process as described in Example-1, was added to a mixture of 225 ml of acetic acid, 75 ml of conc. hydrochloric acid and 40 ml of water and the mixture was refluxed for 12 hrs. The reaction mixture was cooled to room temperature and 66.2 g of sodium bicarbonate was added and once the evolution of carbondioxide had ceased, the solvent was distilled off applying high vacuum. A 10:1 by volume mixture of benzene and ethyl acetate was added to the residue and the crude product was washed with a mixture of equal volumes of a saturated aq. sodium bicarbonate solution water. The organic layer was dried over anhydrous sodium sulphate and the solvent was distilled off. The resulting crude product was quickly eluted from a WO 97/27191 PCTUS97/02577 24 silica gel column with 50% ethylacetate-hexane to furnish 12.5 g of the required 5-{4-(6-hydroxy-2, 5, 7, 8-tetramethylchroma-2yl-methoxy) benzyl) thiazolidine- 2,4-dione (Troglitazone) with a HPLC purity of -67-70%.

5 g of crude Troglitazone so obtained was taken in ~-ml of acetone and -100 ml benzene was added and heated on a steam bath till the solid dissolved completely. The solution was rapidly cooled to -10 0

C.,

at a rate of 10*C./minute, over a period of 15 min.

while scratching to yield 2.5 g of 99% pure polymorphic Form-2 of Troglitazone.

Example-7: g of crude Troglitazone obtained by the process as described in Example-i was taken in -100 ml benzene and heated on steam bath till the solid completely dissolved. The solution was rapidly cooled to -10 0 at a rate of 10°C./minute, over a period of min. while scratching to yield 40 g of 99% pure polymorphic Form-2 of Troglitazone.

Example-8: g of crude Troglitazone obtained by the process as described in Example-i and 5 ml acetone were taken in 100 ml round bottom flask and stirred on a magnetic stirrer till all the solid dissolved in acetone. Acetone was completely removed under vacuum at 50 0 and then -25 ml dichloromethane was added to the gummy residue and stirred at 5 0 C. for hr. ml. of Pet ether was added and scratched the walls of the container. Stirring at 5 0 C. was continued for another 1 hr. The solid was filtered and dried to yield 2.7 g 99% pure polymorphic Form-2 of Troglitazone.

Example 9 illustrates the process for the preparation of the polymorphic Form-3 of Troglitazone Example-9: g of the polymorphic Form-2 of WO 97/27191 PCT/US97/02577 25 Troglitazone obtained by the process as described in Example-8, was dissolved in 25 ml acetone and the solvent was completely removed. ~50 ml benzene was added to the gummy mass and heated on a steam bath for 15-30 min. The clear solution was cooled to 5 0 C. at a rate of 1 0 C./minute during a period of 24 h to yield g of 99% pure polymorphic Form-3 of Troglitazone.

Examples 10-14 illustrate the process for the preparation of the polymorphic Form-4 of Troglitazone g the polymorphic Form-i of Troglitazone obtained by the process described in Example-2, was heated to melt and the resulting transparent flake was crushed to give a yellowish white fine powder of the polymorphic Form-4 of Troglitazone in near quantitative yield. This material exhibited typical liquid crystalline/amorphous nature.

EXAMPLE-11: 5 g of the polymorphic Form-2 of Troglitazone obtained by the process described in Example-5, was heated to melt and the resulting transparent flake was crushed to yield a yellowish white powder of the polymorphic Form-4 of Troglitazone in near quantitative yield which was found to be similar in all respects to the product obtained in Example-12: g of the polymorphic Form-3 of Troglitazone obtained by the process described in Example-9, was heated to melt and the resulting transparent flake was crushed to yield a yellowish white powder of the polymorphic Form-4 of Troglitazone in near quantitative yield which was found to be similar in all respects to the product obtained in Example-10 and 11.

Example-13: g of the polymorphic Form-5 of Troglitazone was heated to melt and the resulting transparent flake WO 97/27191 PCT/US97/02577 26 was crushed to yield a yellowish white powder of the polymorphic Form-4 of Troglitazone in near quantitative yield which was found to be similar in all respects to the product obtained in Examples 10-12.

EXAMPLE-14: g of the polymorphic Form-6 of Troglitazone was heated to melt and the resulting transparent flake was crushed to yield a yellowish white powder of the polymorphic Form-4 of Troglitazone in near quantative yield which was found to be similar in all respects to the product obtained in Examples 10-13.

Examples 15-19 illustrate the process for the preparation of the polymorphic Form-5 of Troglitazone g of the polymorphic Form-i of Troglitazone obtained by the process described in Example-1, was heated to melt and the resulting transparent flake was crushed to give a yellowish white fine powder of the polymorphic Form-4 of Troglitazone in near quantitative yield. The polymorphic Form-4 of Troglitazone thus obtained was heated isothermally at a temperature in the range of 60 to 170C. preferably 130°C. for a period in the range of 5 min. to 4 h, cooled to room temperature at a rate of 0.1 to 1 0 C./minute and crushed the resulting material to give the polymorphic of Troglitazone in near quantitative yield.

EXAMPLE 16: g of the polymorphic Form-2 of Troglitazone, obtained by the process described in was heated to melt and the resulting transparent flake was crushed to give a yellowish white fine powder of the polymorphic Form-4 of Troglitazone in near quantitative yield. The polymorphic Form-4 of Troglitazone thus obtained was heated isothermally at a temperature in the range of 60 to 170°C. preferably 130 0 C. for a period in the range of 5 min. to 4 h, WO 97/27191 PCT/US97/02577 27 cooled to room temperature at a rate of 0.1 to l1C./minute and crushed the resulting material to give the polymorphic Form-5 of Troglitazone in near quantitative yield.

EXAMPLE-17: g of the polymorphic Form-3 of Troglitazone obtained by the process described in Example-9, was heated to melt and the resulting transparent flake was crushed to give a yellowish white fine powder of the polymorphic Form-4 of Troglitazone in near quantitative yield. The polymorphic Form-4 of Troglitazone thus obtained was heated isothermally at a temperature in the range of 60 to 170°C. preferably 130°C. for a period in the range of 5 min. to 4 h, cooled to room temperature at a rate of 0.1 to 1 0 C./minute and crushed the resulting material to give the polymorphic of Troglitazone in near quantitative yield.

Example-18: g of the polymorphic Form-4 of Troglitazone obtained by the process described in Example-11, was heated isothermally at a temperature in the range of to 170°C. preferably 130°C. for a period in the range of 5 min. to 4 h, cooled to room temperature at a rate of 0.1 to 1 0 C./minute and crushed the resulting material to give the polymorphic Form-5 of Troglitazone in near quantitative yield.

Example-19: g of the polymorphic Form-6 of Troglitazone, was heated to melt and the resulting transparent flake was crushed to give a yellowish white fine powder of the polymorphic Form-4 of Troglitazone in near quantitative yield. The polymorphic Form-4 of Troglitazone thus obtained was heated isothermally at a temperature in the range of 60 to 170 0 C. preferably 130 0 C. for a period in the range of 5 min. to 4 h, cooled to room temperature at a rate of 0.1 to 1 0 C./minute and crushed the resulting material to give WO 97/27191 PCT/US97/02577 28 the polymorphic Form-5 of Troglitazone in near quantitative yield.

Examples 20-21 illustrate the process for the preparation of the polymorphic Form-6 of Troglitazone g of crude Troglitazone obtained by the process as described in Example-1 was dissolved in ml of acetone and to this was added 100 ml of benzene.

The clear solution thus obtained was rapidly cooled to 0 C. at the rate of 10 0 C./minute and allowed to stand at 5°C. for 12 h to yield 2.5 g of 99.0% pure polymorphic Form-6 of Troglitazone.

Example-21: 15.5g of 5[ 4 -(6-hydroxy-2,5,7,8-tetramethyl chroman-2yl-methoxy) benzyl]-2-iminothiasolidine-4-one, prepared by the process as described in Example-1, was added to a mixture of 225 ml of acetic acid, 75 ml of cone. hydrochloric acid and 40 ml of water and the mixture was refluxed for 12 hrs. The reaction mixture was cooled to room temperature and 66.2 g of sodium bicarbonate was added and once the evolution of carbondioxide had ceased, the solvent was distilled off applying high vacuum. A 10:1 by volume mixture of benzene and ethyl acetate was added to the residue and the crude product was washed with a mixture of equal volumes of a saturated aq. sodium bicarbonate solution water. The organic layer was dried over anhydrous sodium sulphate and the solvent was distilled off.

The resulting crude product was quickly eluted from a silica gel column with 50% ethylacetate-hexane to finish 12.5 g of the required 5-{4-(6-hydroxy-2, 5, 7, 8-tetramethylchroman-2-yl-methoxy) benzyl) thiazolidine-2,4-dione (Troglitazone) with a HPLC purity of- 67-70%.

g of crude Troglitazone as obtained above was dissolved in 25 ml of acetone and to this was added WO 97/27191 PCT/US97/02577 29 100 ml of benzene. The clear solution thus obtained was rapidly cooled to 5 0 C. at the rate of 10 0 C./minute and allowed to stand at 5 C. for 12 h to yield 2.5 g of 99.0% pure polymorphic Form-6 of Troglitazone.

ADVANTAGES OF THE INVENTION The polymorphic forms of Troglitazone are more active/bio-available.

Ease in formulation resulting in higher activity/bio-availability, in terms of lowering plasma blood sugar and plasma triglycerides.

Claims (18)

1. A polymorphic form 1 of Troglitazone having the formula I, 0 0 S' 0 NH 0 characterized by the data: DSC: Endotherm at 179.3 0 C.(onset at 169.3 0 X-ray powder diffraction 5.56, 11.10, 11.66, 15.72, 16.62, 17.62,

18.24, 19.70, 21.20, 21.42, 23.40, 23.70; and Infrared absorption bands (cm 1 3442(w), 3218(w), 2921(w), 1748(m), 1686(s), 1610(w), 1582(w), 1513(s), 1454(w), 1420(w), 1382(w), 1302(m), 1244(s), 1169(m), 1118(w), 1086(w), 1048(m), 931(w), 863(w), 827(w), 798(w), 720(w), 509(w) wherein w weak, m medium, and s strong. 2. A polymorphic form 2 of Troglitazone having the formula I, NH o (onset at 155.9C.); X-ray powder diffraction 5.42, 1024, 10.72, 11.58, 11.72, 15.60, (onset at 155.9°C.); X-ray powder diffraction 5.42, 10.24, 10.72, 11.58, 11.72, 15.60, 17.56, 18.16, 19.48, 19.58, 19.68, 21.44, 22.20, 23.28, 23.66, 24.14, 24.38; and Infrared absorption bands 3506(w), 3187(w), 3061(w), 2931(w), 1751(m), 1688(s), 1610(w), 1583(w), 1512(s), 1454(w), 1419(w), 1381(w), 1334(w), 1301(m), 1252(s), 1165(m), 1088(w), 1047(w), 932(w), 828(w), 722(w), 511(w) wherein w weak, m medium, and s strong. 3. A polymorphic form 3 of Troglitazone having the formula I; 0S NH 0 characterized by the data: DSC: Endotherm at 185.8 0 C. (onset at 175.4°C.); X-ray powder diffraction 5.44, 11.74, 13.24, 15.62, 16.02, 17.56, S:o* 18.12, 19.65, 21.41, 23.00, 23.31, 23.65, 24.43, 26.51; and Infrared absorption bands 3439(w), 3295(w), 2972(w), 2932(w), 1747(m), 1690(s), 1611(w), 1582(w), 1512(s), 1453(m), 1384(w), 1302(m), 1245(s), 1221(s), 1169(s), 1143(w), 1119(w), 1089(w), 1049(w), 931(w), 828(w), 722(w), 510(w) wherein w weak, m medium, and s strong. 4. A polymorphic form 4 of Troglitazone having the formula I, N H 0 characterized by the data: DSC: Endotherm at 56.6 0 exotherm at 110.4 0 C. (onset at 93.6 0 and endotherm 177.1°C. (onset at 153.7 0 X-ray powder diffraction No diffraction peaks due to its amorphous nature; and Infrared absorption bands 3473(w), 3204(w), 3060(w), 2 924(w), 1754(m), 1696(s), 1610(w), 1583(w), 1512(s), 1457(m), 1420(w), 1378(w), 13 3 3(m), 1301(m), 1243(s), 1162(m), 1115(w), 1085(w), 1041(w), 928(w), 849(w), 827(w), 715(w), 664(w), 512(w) wherein w weak, m medium, and s strong. A polymorphic form 5 of Troglitazone having the formula I, 0 0 0 S 0 O 'NH 0 characterized by the data: DSC: Endotherm at 180.5 0 C. (onset at 157.9 0 X-ray powder diffraction 5.60, 11.06, 11.62, 15.48, 15.78, 16.48, 18.12, 18.34, 21.06, 21.90, 23.34, 23.58; and Infrared absorption bands 3462(w), 3211(w), 3060(w), 2921(w), 1756(m), 1685(s), 1610(w), 1583(w), 1513(s), 1454(m), 1419(w), 1381(w), 1303(m), 1244(s), 1168(m), 1117(w), 1085(w), 1047(m), 929(w), 861(w), 825(w), 718(w), 665(w), 564(w), 509(w) wherein 6w weak, m medium, and s strong. 6. A polymorphic form 6 of Troglitazone having the formula I, 0* 0 O NH *0 33 characterized by the data: DSC: Endotherm at 105.4C. (onset at 94.8 0 X-ray powder diffraction 5.36, 8.54, 10.24, 10.70, 11.24, 12.48, 12.68, 15.58, 18.84, 19.48, 19.74, 20.58, 21.38, 21.56, 22.18; and Infrared absorption bands 3634(w), 3514(w), 3176(w), 3060(w), 2930(w), 1753(m), 1686(s), 1610(w), 1512(s), 1459(w), 1418(w), 1380(w), 1335(m), 1300(m), 1253(s), 1164(s), 1106(w), 1087(w), 1058(w), 1048(w), 937(w), 828(m), 723(w), 673(w), 606(w), 568(w), 515(w) wherein w weak, m medium, and s strong. 7. A pharmaceutical composition comprising a polymorphic form 1 of Troglitazone having the formula I, NH 0 0 O 560 characterized by the data: DSC: Endotherm at 179.3 0 C. (onset at 169.3 0 X-ray powder diffraction 5.56, 11.10, 11.66, 15.72, 16.62, 17.62, 18.24, 19.70, 21.20, 21.42, 23.40, 23.70; and Infrared absorption bands 3442(w), 3218(w), 2921(w), 1748(m), 1686(s), 1610(w), 1582(w), 1513(s), 1454(w), 1420(w), 1382(w), 1302(m), 1244(s), 1169(m), 1118(w), 1086(w), 1048(m), 931(w), 863(w), 827(w), 798(w), 720(w), 509(w) wherein w weak, m medium, and s strong and a pharmaceutically acceptable carrier, diluent or solvent. S 8. A pharmaceutical composition comprising a polymorphic form 2 of Troglitazone having the formula I, o 0 -Sy NH O characterized by the data: DSC: Endotherms at 110.1 0 C. (onset at 102.4 0 and at 175.1 0 C. (onset at 155.9 0 X-ray powder diffraction 5.42, 10.24, 10.72, 11.58, 11.72, 15.60, 17.56, 18.16, 19.48, 19.58, 19.68, 21.44, 22.20, 23.28, 23.66, 24.14, 24.38; and Infrared absorption bands (cm- 1 3506(w), 3187(w), 3061(w), 2931(w), 1751(m), 1688(s), 1610(w), 1583(w), 1512(s), 1454(w), 1419(w), 1381(w), 1334(w), 1301(m), 1252(s), 1165(m), 1088(w), 1047(w), 932(w), 828(w), 722(w), 511(w) wherein w weak, m medium, and s strong and a pharmaceutically acceptable carrier, diluent or solvent. 9. A pharmaceutical composition comprising a polymorphic form 3 of Troglitazone having the formula I, *S NH 0 characterized by the data: DSC: Endotherm at 185.8 0 C. (onset at 175.4 0 X-ray powder diffraction 5.44, 11.74, 13.24, 15.62, 16.02, 17.56, 18.12, 19.65, 21.41, 23.00, 23.31, 23.65, 24.43, 26.51; and SInfrared absorption bands 3439(w), 3295(w), 2972(w), 2932(w), S• 1747(m), 1690(s), 1611(w), 1582(w), 1512(s), 1453(m), 1384(w), 1302(m), 1245(s), 1221(s), 1169(s), 1143(w), 1119(w), 1089(w), 1049(w), 931(w), 828(w), 722(w), 510(w) wherein w weak, m medium, and s strong and a pharmaceutically acceptable carrier, diluent or solvent. A pharmaceutical composition comprising a polymorphic form 4 of Troglitazone having the formula I, 0 characterized by the data: DSC: Endotherm at 56.6 0 exotherm at 110.4 0 C. (onset at 93.6 0 C.) S* and endotherm 177.1°C. (onset at 153.7 0 X-ray powder diffraction No diffraction peaks due to its amorphous nature; and Infrared absorption bands 3473(w), 3204(w), 3060(w), 2924(w), 1754(m), 1696(s), 1610(w), 1583(w) 1512(s), 1457(m), 1420(w), 1378(w), 1333(m), 1301(m), 1243(s), 1162(m), 1115(w), 1085(w), 1041(w), 928(w), 849(w), 827(w), 715(w), 664(w), 512(w) wherein w weak, m medium, and s strong and a pharmaceutically acceptable carrier, diluent or solvent. 11. A pharmaceutical composition comprising a polymorphic form 5 of Troglitazone having the formula I, a 0 characterized by the data: DSC: Endotherm at 180.5 0 C. (onset at 157.9 0 X-ray powder diffraction 5.60, 11.06, 11.62, 15.48, 15.78, 16.48, 18.12, 18.34, 21.06, 21.90, 23.34, 23.58; and Infrared absorption bands 3462(w), 3211(w), 3 060(w), 2921(w), 1756(m), 1685(s), 1610(w), 1583(w), 1513(s), 1454(m), 1419(w), 1381(w), 1303(m), 1244(s), 1168(m), 1117(w), 1085(w), 1047(m), 929(w), 861(w), 825(w), 718(w), 665(w), 564(w), 509(w) wherein w weak, m medium, and s strong and a pharmaceutically acceptable carrier, diluent or solvent. 12. A pharmaceutical composition comprising a polymorphic form 6 of Troglitazone having the formula I, O NH O characterized by the data: DSC: Endotherm at 105.4°C. (onset at 94.8 0 X-ray powder diffraction 5.36, 8.54, 10.24, 10.70, 11.24, 12.48, 12.68, 15.58, 18.84, 19.48, 19.74, 20.58, 21.38, 21.56, 22.18; and Infrared absorption hands (cm 1 3634(w), 3514(w), 3176(w), 3060(w), 2930(w), 1753(m), 1686(s), 1610(w), 1512(s), 1459(w), 1418(w), 1380(w), 1335(m), 1300(m), 1253(s), 1164(s), 1106(w), 1087(w), 1058(w), 1048(w), 937(w), 828(m), 723(w), 673(w), 606(w), 568(w), 515(w) wherein w weak:, m medium, and s strong and a pharmaceutically acceptable carrier, diluent or solvent. *0* 0 Use of a polymorphic form 1 of Troglitazone having the form I, S oO 0 C C C 0 C S CO C 0 0@ S 6 S characterized by the data: DSC: Endotherm at 179.3 0 C. (onset at 169.3 0 X-ray powder diffraction 5.56, 11.10, 11.66, 15.72, 16.62, 17.62, 18.24, 19.70, 21.20, 21.42, 23.40, 23.70; and Infrared absorption bands 3442(w), 3218(w), 2921(w), 1748(m), 1686(s), 1610(w), 1582(w), 1513(s), 1454(w), 1420(w), 1382(w), 1302(m), 1244(s), 1169(m), 1118(w), 1086(w), 1048(m), 931(w), 863(w), 827(w), 798(w), 720(w), 509(w) wherein w weak, m medium, and s strong for the treatment of diabetic ailments. 14. Use of a polymorphic form 2 of Troglitazone having the formula I, 0 NH characterized by the data: DSC: Endotherms at 110.1 0 C. (onset at 102.4 0 and at 175.1C. (onset at 155.9 0 X-ray powder diffraction 5.42, 10.24, 10.72, 11.58, 11.72, 15.60, 17.56, 18.16, 19.48, 19.58, 19.68, 21.44, 22.20, 23.28, 23.66, 24.14, 24.38; and Infrared absorption bands 3506(w), 3187(w), 3061(w), 2931(w), 1751(m), 1688(s), 1610(w), 1583(w), 1512(s), 1454(w), 1419(w), 1381(w), 1334(w), 1301(m), 1252(s), 1165(m), 1088(w), 1047(w), 932(w), 828(w), 722(w), 511(w) wherein w weak, m medium, and s strong for the treatment of diabetic ailments. Use of a polymorphic form 3 of Troglitazone having the formula I, 0 O NH 0 characterized by the data: DSC: Endotherm at 185.8 0 C. (onset at 175.4C.); X-ray powder diffraction 5.44, 11.74, 13.24, 15.62, 16.02, 17.56, 18.12, 19.65, 21.41, 23.00, 23.31, 23.65, 24.43, 26.51; and 7 Infrared absorption bands (cm- 1 3439(w), 3295(w), 2972(w), 2932(w), .1747(m), 1690(s), 1611(w), 1582(w), 1512(s), 1453(m), 1384(w), 1302(m), 1245(s), 1221(s), 1169(s), 1143(w), 1119(w), 1089(w), 1049(w), 931(w), 828(w), 722(w), 510(w) wherein w weak, m medium, and s strong for the treatment of diabetic ailments. 16. Use of a polymorphic form 4 of Troglitazone having the formula I, 0- 0 •0 H NH o characterized by the data: DSC: Endotherm at 56.6 0 exotherm at 110.4 0 C. (onset at 93.6 0 C.) 39 and endotherm 177.1 0 C. (onset at 153.7 0 X-ray powder diffraction No diffraction peaks due to its amorphous nature; and Infrared absorption bands 3473(w), 3204(w), 3060(w), 2924(w), 1754(m), 1696(s), 1610(w), 1583(w), 1512(s), 1457(m), 1420(w), 1378(w), 1333(m), 1301(m), 1243(s), 1162(m), 1115(w), 1085(w), 1041(w), 928(w),.849(w), 827(w), 715(w), 664(w), 512(w) wherein w weak, m medium, and s strong for the treatment of diabetic ailments. 17. Use of a polymorphic form 5 of Troglitazone having the formula I, H NH O S S S S 5 *r S 6@ S. S. 0, S 0 0e characterized by the data: DSC: Endotherm at 180.5 0 C. (onset at 157.9 0 X-ray powder diffraction 5.60, 11.06, 11.62, 15.48, 15.78, 16.48, 18.12, 18.34, 21.06, 21.90, 23.34, 23.58; and Infrared absorption bands 3462(w), 3211(w), 3060(w), 2921(w), 1756(m), 1685(s), 1610(w), 1583(w), 1513(s), 1454(m), 1419(w), 1381(w), 1303(m), 1244(s), 1168(m), 1117(w), 1085(w), 1047(m), 929(w), 861(w), 825(w), 718(w), 665(w), 564(w), 509(w) wherein w weak, m medium, and s strong for the treatment of diabetic ailments. 18. Use of a polymorphic form 6 of Troglitazone having the formula I, 0s o H NH O characterized by the data: DSC: Endotherm at 105.4 0 C. (onset at 94.8 0 X-ray powder diffraction 5.36, 8.54, 10.24, 10.70, 11.24 12.48, 12.68, 15.58, 18.84, 19.48, 19.74, 20.58, 21.38, 21.56, 22.18; and Infrared absorption bands (cm- 1 3634(w), 3514(w), 3 176(w), 3 060(w), 2930(w), 1753(m), 1686(s), 1610(w), 1512(s), 1459(w), 1418(w), 1380(w), 1335(m), 1300(m), 1253(s), 1164(s), 1106(w), 1087(w), 1058(w), 1048(w), 937(w), 828(m), 723(w), 673(w), 606(w), 568(w), 515(w) wherein w weak, m medium, and s strong for the treatment of diabetic ailments.

19. A process for preparing the polymorphic form 1 of Troglitazone of claim 1, which comprises: synthesizing Troglitazone, in crude form employing known methods, (ii) subjecting the crude Troglitazone obtained in step to column chromatography to obtain a partially purified Troglitazone having HPLC purity in the range of 60 (iii) dissolving the partially purified Troglitazone obtained in step (ii) in an organic polar solvent, a medium polar solvent or a mixture thereof and heating the resulting solution with an organic non-polar solvent and (iv) cooling the resulting solution slowly to room temperature at a rate of 0.1 to 1°C./minute over a period in the range of 24-72 h to produce the polymorphic *0 form 1 of Troglitazone. A process for preparing the polymorphic form 2 of Troglitazone of claim 2, which comprises: synthesizing Troglitazone, in crude form employing known methods, (ii) subjecting the crude Troglitazone obtained in step to column chromatography to obtain a partially purified Troglitazone having HPLC purity in the range of 60 (iii) dissolving the partially purified Troglitazone obtained in step (ii) in an organic polar solvent, and heating the resulting solution with an organic non-polar solvent and (iv) scratching the resulting solution, while cooling to a temperature between 0 to -20 0 C. at a rate of 2 to 10 0 C./minute over a period in the range of 10-30 min. to precipitate the polymorphic form 2 of Troglitazone.

21. A process for preparing the polymorphic form 3 of Troglitazone of claim 3, which comprises: synthesizing Troglitazone, in crude form employing known methods, (ii) subjecting the crude Troglitazone obtained in step to column chromatography to obtain a partially purified Troglitazone having HPLC purity in the range of 60 (iii) dissolving the partially purified Troglitazone obtained in step (ii) in an organic polar solvent, and heating the resulting solution with an organic non-polar solvent, (iv) scratching the resulting solution, while cooling to a temperature between 0 to -20 0 C. at a rate of 2 to 10 0 C./minute over a period in the range of 10-30 min. to precipitate the polymorphic form 2 of Troglitazone, dissolving the polymorphic form 2 of Troglitazone obtained in step (iv) in an organic polar solvent, and heating the resulting solution with an organic non- polar solvent and (vi) cooling the solution to room temperature at a rate of 0.1 to l°C./minute over a period in the range of 24-72 h to crystallize polymorphic form 3 of 0 Troglitazone.

22. A process for preparing the polymorphic form 4 of Troglitazone of claim 4, which comprises: synthesizing Troglitazone, in crude form employing known methods, (ii) subjecting the crude Troglitazone obtained in step to column chromatography to obtain a partially purified Troglitazone having HPLC purity in the range of 60-70%, (iii) dissolving the partially purified Troglitazone obtained in step (ii) in .an organic polar solvent, and heating the resulting solution with an organic non-polar solvent, (iv) cooling the resulting solution to room temperature at a rate of 0.1 to 1 C./minute over a period in the range of 24-72 h to produce the polymorphic form 1 of Troglitazone, filtering the polymorphic form 1 of Troglitazone and melting it by heating, (vi) cooling the melt to ambient temperature at a rate of 0.1 to 1 0 C./minute over a period in the range of 1-4 h to give a transparent material, and (vii) grinding the transparent material to a powder to yield the polymorphic form 4 of Troglitazone.

23. A process for preparing the polymorphic form 4 of Troglitazone of claim 4, which comprises: synthesizing Troglitazone, in crude form employing known methods, (ii) subjecting the crude Troglitazone obtained in step to column chromatography to obtain a partially purified Troglitazone having HPLC purity in the range of 60-70%, (iii) dissolving the partially purified Troglitazone obtained in step (ii) in an organic polar solvent, and heating the resulting solution with an organic non-polar solvent, (iv) scratching the resulting solution while cooling to a temperature between 0 to -20 0 C. at a rate of 2 to 10 0 C./minute over a period in the range of 10-30 min. to precipitate the polymorphic form 2 of Troglitazone, filtering the polymorphic form 2 of Troglitazone and melting it by heating, (vi) cooling the melt of step to ambient temperature at a rate of 0.1 to 1 C./minute over a period in the range of 1-4 h to give a transparent material, and (vii) grinding the transparent material to a powder to yield the polymorphic form 4 of Troglitazone. •24. A process for preparing the polymorphic form 4 of Troglitazone of claim 4, which comprises: synthesizing Troglitazone, in crude form employing known methods, S (ii) subjecting the crude Troglitazone obtained in step to column chromatography to obtain a partially purified Troglitazone having HPLC purity in the range of 60-70%, (iii) dissolving the partially purified Troglitazone obtained in step (ii) in an organic polar solvent, and heating the resulting solution with an organic non-polar solvent, (iv) scratching the resulting solution, while cooling to a temperature in the range of 0 to -20 0 C. at a rate of 2 to 10 0 C./minute over a period in the range of min. to precipitate the polymorphic form 2 of Troglitazone, dissolving the polymorphic form 2 of Troglitazone obtained in step in an organic polar solvent, and heating the resulting solution with an organic non- polar solvent, (vi) cooling the solution to room temperature at a rate of 0.1 to 1 C./minute, over a period in the range of 24-72 h to crystallize polymorphic form 3 of Troglitazone, (vii) filtering the polymorphic form 3 of Troglitazone and melting it by heating, (viii) cooling the melt of step (vii) to ambient temperature at a rate of S0.1 to 1 0 C./minute, over a period in the range of 1-4 h to give a transparent material, and (ix) grinding the transparent material to a powder to yield the polymorphic form 4 of Troglitazone. I 25. A process for preparing the polymorphic form 5 Troglitazone of claim which comprises: synthesizing Troglitazone, in crude form employing known methods, (ii) subjecting the crude Troglitazone obtained in step to column chromatography to obtain a partially purified Troglitazone having HPLC purity in the range of 60-70%, (iii) dissolving the partially purified Troglitazone obtained in step (ii) in an organic polar solvent, and heating the resulting solution with an organic non-polar we. solvent, (iv) cooling the resulting solution to room temperature at a rate of 0.1 to 1 C./minute, over a period in the range of 24-72 h to produce polymorphic form 1 of Troglitazone, filtering the polymorphic form 1 of Troglitazone and melting it by heating, (vi) cooling the melt of step to ambient temperature at a rate in the range of 0.1 to 1 C/minute over a period of 1-4 h to give a transparent material, (vii) grinding the transparent material to a powder to yield polymorphic form 4 of Troglitazone, and (viii) subjecting the polymorphic form 4 of Troglitazone as obtained in step (vii) to isothermal heating in the range of 60 to 170 0 C. for a period in the range of min. to 4 h, cooling to ambient temperature at a rate of 0.1 to 1 C./minute, over a period in the range of 1-4 h, followed by grinding to a powder to yield the polymorphic form 5 of Troglitazone.

26. A process for preparing polymorphic form 5 of Troglitazone of claim which comprises: synthesizing Troglitazone, in crude form employing known methods, (ii) subjecting the crude Troglitazone obtained in step to column oo. chromatography to obtain a partially purified Troglitazone having HPLC purity in the range of 60 S* (iii) dissolving the partially purified Troglitazone obtained in step (ii) in an organic polar solvent, and heating the resulting solution with an organic non-polar solvent, (iv) scratching while cooling to a temperature in the range of 0 to -20 0 C. at a rate of 2 to 10 0 C./minute, over a period in the range of 10-30 min. to precipitate So** the polymorphic form 2 of Troglitazone, filtering the polymorphic form 2 of Troglitazone and melting it by heating, (vi) cooling the melt of step to ambient temperature at a rate in the range of 0.1 to l°C./minute over a period of 1-4 h to give a transparent material, (vii) grinding the transparent material to a powder to yield the S polymorphic form 4 of Troglitazone, and (viii) subjecting the polymorphic form 4 of Troglitazone obtained in step (vii) to isothermal heating in the range of 60 to 170C. for a period in the range of min. to 4 h, cooling to ambient temperature at a rate of 0.1 to 1 C./minute, over a period in the range of 1-4 h, followed by grinding to a powder to yield the polymorphic form 5 of Troglitazone.

27. A process for preparing polymorphic form 5 of Troglitazone of claim which comprises: synthesizing Troglitazone, in crude form employing known methods, (ii) subjecting the crude Troglitazone obtained in step to column chromatography to obtain a partially purified Troglitazone having HPLC purity in the range of 60-70%, (iii) dissolving the partially purified Troglitazone obtained in step (ii) in an organic polar solvent, and heating the resulting solution with an organic non-polar solvent, (iv) scratching the solution of step (iii) while cooling to a temperature S in the range of 0 to -20 0 C. at a rate of 2 to 10 0 C./minute, over a period in the range of S. 10-30 min. to precipitate the polymorphic form 2 of Troglitazone, dissolving the polymorphic form 2 of Troglitazone obtained in step (iv) in an organic polar solvent, and heating the resulting solutions with an organic S non-polar solvent, (vi) cooling the solution to room temperature at a rate of 0.1 to 1lC./minute, over a period in the range of 24-72 h to crystallize polymorphic form 3 of Troglitazone, (vii) filtering the polymorphic form 3 of Troglitazone and melting it by heating, (viii) cooling the melt of step (vii) to ambient temperature at a rate of 0.1 to 1 C./minute, over a period in the range of 1-4 h to give a transparent material, (ix) grinding the transparent material to a powder to yield polymorphic form 4 of Troglitazone, and 0• subjecting the polymorphic form 4 of Troglitazone obtained in step (ix) to isothermal heating in the range of 60 to 170 0 C. for a period in the range of min. to 4 h, cooling to ambient temperature at a rate of 0.1 to 1 C./minute, over a period in the range of 1-4 h, followed by grinding to a powder to yield the polymorphic form 5 of Troglitazone.

28. A process for preparing polymorphic form 6 of Troglitazone of claim 6, which comprises: synthesizing Troglitazone, in crude form employing known methods, (ii) subjecting the crude Troglitazone obtained in step to column chromatography to obtain a partially purified Troglitazone having HPLC purity in the range of 60-70%, (iii) dissolving the partially purified Troglitazone obtained in step (ii) in an organic polar solvent, and adding an organic non-polar solvent to the resulting solution and (iv) cooling the resulting solution to about 5°C. at a rate of 0 C./minute and maintaining the temperature at about 5 0 C. for a period of 10-16 h to produce the polymorphic form 6 of Troglitazone,

29. A process for preparing polymorphic form 4 of Troglitazone of claim 4, .which comprises: melting a polymorphic form 5 of Troglitazone by heating, (ii) cooling the melt of step to ambient temperature at a rate of 0.1 to l°C./minute, over a period in the range of 1-4 h to give a transparent material, and (iii) grinding the transparent material to a powder to yield the polymorphic form 4 of Troglitazone. A process for preparing polymorphic form 4 of Troglitazone of claim 4, which comprises: melting a polymorphic form 6 of Troglitazone by heating, (ii) cooling the melt of step to ambient temperature at a rate of 0.1 to l°C./minute, over a period in the range of 1-4 h to give a glossy transparent material, and (iii) grinding the transparent material to a powder to yield the Spolymorphic form 4 of Troglitazone.

31. A process for preparing polymorphic form 5 of Troglitazone of claim which comprises: melting polymorphic form 6 of Troglitazone by heating, (ii) cooling the melt of step to ambient temperature at a rate of 0.1 to 1 C./minute, over a period in the range of 1-4 h to give a transparent material, (iii) grinding the transparent material to a powder to yield polymorphic form 4 of Troglitazone, and (iv) subjecting the polymorphic form 4 of Troglitazone obtained in step (iii) to isothermal heating in the range of 60 to 170C. for a period in the range of min. to 4 h, cooling to ambient temperature slowly at a rate of 0.1 to 1 C./minute, over a period in the range of 1-4 h followed by grinding to a powder to yield polymorphic form 5 of Troglitazone.

32. A pharmaceutical composition comprising a polymorphic form of Troglitazone according to any one of claims 1-6, and one or more pharmaceutically acceptable carriers, excipients, or diluents.

33. A method of treating diabetic ailments comprising administering to a patient in need thereof at least one of a polymorphic form of Troglitazone according to claims 1-6 said polymorphic form of Troglitazone selected from the group consisting of polymorphic form 1 of Troglitazone, polymorphic form 2 of Troglitazone, polymorphic form 3 of Troglitazone, polymorphic form 4 of Troglitazone, polymorphic form 5 of o Troglitazone, and polymorphic form 6 of Troglitazone.

34. Use of a polymorphic form 1 of Troglitazone having the form I, O S NH 0 characterized by the data: DSC: Endotherm at 179.3 0 C. (onset at 169.3 0 X-ray powder diffraction 5.56, 11.10, 11.66, 15.72, 16.62, 17.62, 18.24, 19.70, 21.20, 21.42, 23.40, 23.70; and Infrared absorption bands 3442(w), 3218(w), 2921(w), 1748(m), 1686(s), 1610(w), 1582(w), 1513(s), 1454(w), 1420(w), 1382(w), 1302(m), 1244(s), 48 1169(m), 1118(w), 1086(w), 1048(m), 931(w), 863(w), 827(w), 798(w), 720(w), 509(w) wherein w weak, m medium, and s strong for the manufacture of a medicament for the treatment of diabetic ailments. Use of a polymorphic form 2 of Troglitazone havine the formula I, 0 NH 0 characterized by the data: DSC: Endotherms at 110.1 0 C. (onset at 102.4 0 and at 175.1 0 C. (onset at 155.9 0 X-ray powder diffraction 5.42, 10.24, 10.72, 11.58, 11.72, 15.60, 17.56, 18.16, 19.48, 19.58, 19.68, 21.44, 22.20, 23.28, 23.66, 24.14, 24.38; and 0 Infrared absorption bands 3506(w), 3187(w), 3061(w), 2931(w), 1751(m), 1688(s), 1610(w), 1583(w), 1512(s), 1454(w), 1419(w), 1381(w), 1334(w), 1301(m), 1252(s), 1165(m), 1088(w), 1047(w), 932(w), 828(w), 722(w), 511(w) wherein w weak, m medium, and s strong for the manufacture of a medicament for the treatment of diabetic ailments.

36. Use of a polymorphic form 3 of Troglitazone having the formula I, S o NH characterized by the data: DSC: Endotherm at 185.8"C. (onset at 175.4 0 X-ray powder diffraction 5.44, 11.74, 13.24, 15.62, 16.02, 17.56, 18.12, 19.65, 21.41, 23.00, 23.31, 23.65, 24.43, 26.51; and 49 Infrared absorption bands 3439(w), 3295(w), 2972(w), 2932(w), 1747(m), 1690(s), 1611(w), 1582(w), 1512(s), 1453(m), 1384(w), 1302(m), 1245(s), 1221(s), 1169(s), 1143(w), 1119(w), 1089(w), 1049(w), 931(w), 828(w), 722(w), 510(w) wherein w weak, m medium, and s strong for the manufacture of a medicament for the treatment of diabetic ailments.

37. Use of a polymorphic form 4 of Troglitazone having the formula I, NH O characterized by the data: DSC: Endotherm at 56.6 0 exotherm at 110.4 0 C. (onset at 93.6 0 C.) and endotherm 177.1 0 C. (onset at 153.7 0 X-ray powder diffraction No diffraction peaks due to its amorphous nature; and Infrared absorption bands 3473(w), 3204(w), 3060(w), 2924(w), 1754(m), 1696(s), 1610(w), 1583(w), 1512(s), 1457(m), 1420(w), 1378(w), 1333(m), 1301(m), 1243(s), 1162(m), 1115(w), 1085(w), 1041(w), 928(w), 849(w), 827(w), 715(w), 664(w), 512(w) wherein w weak, m medium, and s strong for the manufacture of a medicament for the treatment of diabetic ailments.

38. Use of a polymorphic form 5 of Troglitazone having the formula I, *0 0 S 0 *H NH characterized by the data: DSC: Endotherm at 180.5C. (onset at 157.9 0 X-ray powder diffraction 5.60, 11.06, 11.62, 15.48, 15.78, 16.48, 18.12, 18.34, 21.06, 21.90, 23.34, 23.58; and Infrared absorption bands (cm- 1 3462(w), 3211(w), 3060(w), 2921(w), 1756(m), 1685(s), 1610(w), 1583(w), 1513(s), 1454(m), 1419(w), 1381(w), 1303(m), 1244(s), 1168(m), 1117(w), 1085(w), 1047(m), 929(w), 861(w), 825(w), 718(w), 665(w), 564(w), 509(w) wherein w weak, m medium, and s strong for the manufacture of a medicament for the treatment of diabetic ailments.

39. Use of a polymorphic form 6 of Troglitazone having the formula I, NH O characterized by the data: DSC: Endotherm at 105.4 0 C. (onset at 94.8'C.); X-ray powder diffraction 5.36, 8.54, 10.24, 10.70, 11.24, 12.48, 12.68, 15.58, 18.84, 19.48, 19.74, 20.58, 21.38, 21.56, 22.18; and Infrared absorption bands (cm- 1 3634(w), 3514(w), 3176(w), 3060(w), 2930(w), 1753(m), 1686(s), 1610(w), 1512(s), 1459(w), 1418(w), 1380(w), 1335(m), 1300(m), 1253(s), 1164(s), 1106(w), 1087(w), 1058(w), 1048(w), 937(w), 828(m), 723(w), 673(w), 606(w), 568(w), 515(w) wherein w weak, m medium, and s strong for the manufacture of a medicament for the treatment of diabetic ailments. DATED this 17th day of November 1998 DR REDDY'S RESEARCH FOUNDATION and REDDY-CHEMINOR INC By their Patent Attorneys SGriffith Hack