Polymorphic screen and drug–excipient compatibility studies of the antichagasic benznidazole
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The purpose of this study was to investigate the polymorphism and compatibility of benznidazole (BNZ), a drug used in the treatment of Chagas disease. This drug was subjected to a polymorphic screen using a number of solvents and precipitation procedures to explore the possible existence of different crystal structures of BNZ. The compatibility of BNZ with selected pharmaceutical excipients was evaluated in binary mixtures, in a ratio of 1:1 (w/w). These results were then analyzed with a variety of techniques, including differential scanning calorimetry, Fourier transform infrared spectroscopy, and X-ray powder diffractometry. No polymorphic forms of BNZ were detected despite some observed changes in the DSC profile. The thermal data indicate interaction of the drug with excipients hydroxyethylcellulose, polyethylene glycol, and hydroxypropyl-β-cyclodextrin. Additional studies using infrared spectroscopy confirm the incompatibility of BNZ with only the polyethylene glycol. This excipient should not be used in the development of solid dosage forms containing BNZ.
KeywordsBenznidazole Compatibility Differential scanning calorimetry Fourier transform infrared spectroscopy Polymorphism X-ray powder diffractometry
The authors are thankful to LAFEPE, Brazil and Professor José Lamartine Soares Sobrinho, Universidade Federal do Piaui, Brazil, for their charitable donation of the BNZ drug used in our studies. This study was supported by CNPq, Brazil Project number 472134/2008-6. The authors are also thankful for generous help of gift samples of diluents received from Colorcon, Brazil.
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