rifampin and isoascorbic-acid

The validation of a rapid and selective stability-indicating high-performance liquid chromatographic procedure for the determination of rifampicin (RIF) and its decomposition products in aqueous solution is described. Direct injection and column switching HPLC procedures have been compared and, owing to the increased sensitivity and precision, the latter has been applied to the study of RIF stability in the presence of isoascorbic acid at pH 7.4. The time-dependent hydrolytic decomposition of RIF to 3-formyl rifamycin SV (RSV) was found to be biexponential. Log concentration versus time plots of RIF and RSV decomposition were found to be parallel, indicating a pseudo equilibrium decomposition process. This feature allowed corrections for the amounts lost to secondary reactions to be calculated when the assay was applied to the determination of release characteristics of RIF from biodegradable poly-d, l-lactide-co-glycolide microspheres.

Topics: Antibiotics, Antitubercular; Antioxidants; Ascorbic Acid; Biocompatible Materials; Chemistry, Pharmaceutical; Chromatography, High Pressure Liquid; Drug Stability; Hydrogen-Ion Concentration; Kinetics; Lactic Acid; Microspheres; Polyglycolic Acid; Polylactic Acid-Polyglycolic Acid Copolymer; Polymers; Reproducibility of Results; Rifampin