Estudos das propriedades físico-químicas das formas sólidas do sulfametoxazol

Abstract

Sulfamethoxazole (SMX) or 4-amino-N- (5-methyl-3-isoxazolyl) benzenesulfonamide belongs to the group of sulfonamide molecules and is a medicine used in the treatment of bacterial infections, sulfonamides are a structural analogue of paraaminobenzoic acid (PABA ). In the solid state SMX has five different polymorphic forms and several salts. Among the known forms, polymorph I is the one identified in the raw material and drugs of SMX. Among the known forms of SMX, the solid forms chosen of SMX were polymorph I (SMXI), polymorph II (SMXII) and inorganic salts with anions Cl- (SMXCl) and Na + (SMXNa), in order to realize an extensive study of thermal, spectroscopic, solution properties and obtain new solids forms. We have success in the synthesis of two new salts of the SMX with the anions Br- and NO3-. Has been shown, unambiguously, that SMXI and SMXII are enantiotropic polymorphs with a solid-state phase transition at 168 °C. Besides that, SMXII polymorph can be transformed in SMXI by a solid-state phase transition induced for milling process. The solubility of the SMXI and SMXII forms studied in acetonitrile media was showing no significant difference between the polymorphic forms. The comparable solubility’s can be attributed to the phase transitions observed for the residual solid material in equilibrium with the solution during the equilibrium solubility test. The characterization of the salts revealed that the salts SMXNa and SMXBr are more thermally stables, since the decomposition of these salts occurs in temperatures more high, whereas, the solubility experiments showed that salt of SMXNa presents a high solubility in water being close to 49.5 mg mL-1.