HPLC and LC-MS studies on stress degradation behaviour of tinidazole and development of a validated specific stability-indicating HPLC assay method.

The objective of the current investigation was to study the degradation behaviour of tinidazole under different ICH recommended stress conditions by HPLC and LC-MS, and to establish a validated stability-indicating HPLC method. The drug was subjected to stress conditions of hydrolysis, oxidation, photolysis and thermal decomposition. Extensive degradation was found to occur in alkaline medium, under oxidative stress and in the photolytic conditions. Mild degradation was observed in acidic and neutral conditions. The drug was stable to thermal stress. Successful separation of drug from degradation products formed under stress conditions was achieved on a C-18 column using water-acetonitrile (88:12) as the mobile phase. The flow rate was 0.8 ml x min(-1) and the detection wavelength was 310 nm. The method was validated with respect to linearity, precision, accuracy, specificity and robustness. The utility of the procedure was verified by its application to marketed formulations that were subjected to accelerated stability studies. The method well separated the drug and degradation products even in actual samples. The products formed in marketed liquid infusions were similar to those formed during stress studies.