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.

ICH guidance in practice: establishment of inherent stability of secnidazole and development of a validated stability-indicating high-performance liquid chromatographic assay method.

The degradation behaviour of secnidazole was investigated under different stress degradation (hydrolytic, oxidative, photolytic and thermal) conditions recommended by International Conference on Harmonisation (ICH) using HPLC and LC-MS. A stability-indicating HPLC method was developed that could separate drug from degradation products formed under various conditions. Secnidazole was found to degrade significantly in alkaline conditions, oxidative stress, and also in the presence of light. Mild degradation of the drug occurred in acidic and neutral conditions. The drug was stable to dry heat. Resolution of drug and the degradation products formed under different stress studies were successfully achieved on a C-18 column utilizing water-methanol in the ratio of 85:15 and at the detection wavelength of 310 nm. The method was validated with respect to linearity, precision (including intermediate precision), accuracy, selectivity and specificity.

Development of validated stability-indicating assay methods--critical review.

This write-up provides a review on the development of validated stability-indicating assay methods (SIAMs) for drug substances and products. The shortcomings of reported methods with respect to regulatory requirements are highlighted. A systematic approach for the development of stability-indicating methods is discussed. Critical issues related to development of SIAMs, such as separation of all degradation products, establishment of mass balance, stress testing of formulations, development of SIAMs for combination products, etc. are also addressed. The applicability of pharmacopoeial methods for the analysis of stability samples is discussed. The requirements of SIAMs for stability study of biotechnological substances and products are also touched upon.

Validated specific HPLC methods for determination of prazosin, terazosin and doxazosin in the presence of degradation products formed under ICH-recommended stress conditions.

The present paper describes development of stability-indicating high-performance liquid chromatographic (HPLC) assay methods for three alpha-adrenergic-blocker drug substances, namely, prazosin, terazosin and doxazosin, in the presence of degradation products generated from forced decomposition studies. Resolution of drugs from degradation products was obtained using a reversed-phase C-18 column using water/acetonitrile/methanol/glacial acetic acid/diethylamine (25:35:40:1:0.017) as mobile phase for prazosin and terazosin and acetonitrile/water/glacial acetic acid/diethylamine (65:35:1:0.02) for doxazosin. The detection was done at 254 nm. The methods were validated with respect to linearity, precision, accuracy, specificity and robustness.

The ICH guidance in practice: stress decomposition studies on three piperazinyl quinazoline adrenergic receptor-blocking agents and comparison of their degradation behaviour.

Stress degradation studies were carried out on three piperazinyl quinazoline alpha(1)-adrenergic receptor blockers, viz. prazosin, terazosin, and doxazosin, following the conditions prescribed in the parent drug stability testing guideline (Q1AR) issued by International Conference on Harmonization (ICH). All drugs showed significant decomposition at 80 degrees C in acidic conditions (0.1 M HCl) and complete degradation in alkaline conditions (0.1 M NaOH). Under both these conditions, 2-piperazinyl-6,7-dimethoxy-4-aminoquinazoline was formed as a major decomposition product in all three drugs. The degradation pattern under ICH-prescribed photolytic conditions in liquid and solid states was also similar for all the drugs. The light exposure resulted in the formation of a cluster of degradation products. No degradation was observed in neutral and oxidative conditions. In solid state, all drugs were stable at 50 degrees C in a 1-month study. In alkaline conditions, the order of sensitivity to degradation of the three drugs was doxazosin>terazosin>prazosin, while the same was terazosin>doxazosin>prazosin under acidic conditions. Mechanistic explanation is provided for the variable behaviour of decomposition.