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abstracts
Finasteride is a specific competitive inhibitor of steroid type-II 5α-reductase, an intracellular enzyme that converts testosterone to dihydrotestosterone (DHT) and is widely used for the treatment of benign prostatic hyperplasia (BPH), prostate cancer , and androgenetic alopecia. Polymorphs are known to give rise to significant differences in the physicochemical properties of the compound as melting point, density, morphology, solubility and colour. Thus, proper monitoring of solid-state forms, both qualitative and quantitative, is crucial in order to ensure high-quality products. The crystal structures of finasteride appear in the Cambridge Crystal Structure Database (CSD) under the codes WOLXOK01 and WOLXOK02 for Form I and WOLXOK03 for Form II. In this context, the aim of this work was study the behavior of the chemical structure and physicochemical properties of polymorphic forms, and to evaluate the possible influence in the dissolution profile and stability of capsules. A stability study was carried out at 500C for 3 months. The Form II of finasteride was obtained by heating Form I to 2350C for 30 minutes. The techniques X-ray diffraction, infrared spectroscopy and thermal analysis were applied to characterize the Forms. The solubility of finasteride polymorphs was determined by equilibrium solubility method. For the dissolution test, water was used as dissolution medium and the basket apparatus at 100 rpm. The samples were analyzed by HPLC at 210 nm. Differences in X-ray diffraction and infrared spectra of the two polymorphs were observed. The DSC curves showed Form I melting peak at 2570C and solid-solid transformation to Form II at about 2300C. In the solubility study was observed higher Form II solubility than Form I in most evaluated pHs. The interaction of the Forms I and II with capsule excipients may have been different since the dissolution profile of the capsules showed higher release to the Form I. In the stability study, the finasteride content was stable for two Forms, however, the dissolution profile of Form II showed greater decline than the Form I. In conclusion, the results show that the dissolution profiles polymorphism may influence the quality of finasteride capsules, being necessary there be a polymorphic quality control for this dosage Form. Acknowledgments: PNPD CAPES and FAPEMIG
abstracts
Polymorphism in solids is a common phenomenon in drugs, which occurs when an active pharmaceutical ingredient shows up in two or more crystalline forms. The polymorphism may influence the physical and chemical properties of pharmaceutical solids, particularly, solubility and dissolution rates which are very important properties because changes in these parameters may affect the absorption and consequently the bioavailability of drugs (especially those that have a low solubility). Carvedilol is an alpha and beta blocking agent that is used for the treatment of various cardiovascular disorders such as angina pectoris, congestive heart failure and hypertension. This work aims to prepare and characterize the forms II and III of Carvedilol drug and compare them in terms of solubility and dissolution rates. Carvedilol raw material was used as source of form II and Form III, and the last is a hemihydrate of Carvedilol that was obtained by a recrystallization process in ethanol/water 1:1 v/v. Both of the crystalline forms have been identified in this study by Powder X-Ray Diffraction experiments and attenuated total reflectance Fourier transform infrared spectroscopy studies demonstrated that the spectra of forms II and III of Carvedilol have no significant differences. The Thermal Analysis curves, as expected, allowed us to discriminate between the two forms due to a hydratation of Form III. In the solubility study, it was found that the polymorphic Form II is more soluble than Form III in certain conditions (pH 1.0 to 7.2). Dissolution studies have shown that polymorphism may influence the quality of Carvedilol tablets, since form III showed a higher drug release after 20 minutes of dissolution testing. Our results suggest that the identification of polymorphic phases should be a mandatory test for Carvedilol in an official compendium. Acknowledgments: We thank FAPEMIG, FINEP, CAPES and CNPq for their financial support.
