Impact of Ternary Solvent System in Stability-Indicating Assay Method of Bambuterol: Design of Experiments Approach.

High-performance liquid chromatography method for anti-asthmatic ß2-agonist drug bambuterol, its process-related impurities and its major degradation products was developed and validated using quality by design concept. A 3(3) full factorial design was employed to study the effect of three independent factors, namely, ratio of organic modifiers in mobile phase, pH of the buffer and flow rate of the mobile phase. The responses considered were retention time of the last peak and resolution of poorly separated peaks (drug and PR-4 and drug and DP-3). The optimum conditions for separation were determined with the aid of design of experiments. The optimized ternary solvent composition was a mixture of 10 mM ammonium acetate buffer (pH 6.0), methanol and acetonitrile in the ratio of 90:5: 5 (v/v/v) in solvent reservoir A and 10:45:45 (v/v/v) in solvent reservoir B. The separation of the analytes was achieved by using a gradient method. The predictability criteria of the optimized method demonstrated good correlation between observed and predicted response. The method was validated for specificity, linearity, accuracy, precision and robustness in compliance with the International Conference on Harmonization guidelines Q2R1.

Stability-indicating assay method for determination of actarit, its process related impurities and degradation products: Insight into stability profile and degradation pathways☆.

The stability of the drug actarit was studied under different stress conditions like hydrolysis (acid, alkaline and neutral), oxidation, photolysis and thermal degradation as recommended by International Conference on Harmonization (ICH) guidelines. Drug was found to be unstable in acidic, basic and photolytic conditions and produced a common degradation product while oxidative stress condition produced three additional degradation products. Drug was impassive to neutral hydrolysis, dry thermal and accelerated stability conditions. Degradation products were identified, isolated and characterized by different spectroscopic analyses. Drug and the degradation products were synthesized by a new route using green chemistry. The chromatographic separation of the drug and its impurities was achieved in a phenomenex luna C18 column employing a step gradient elution by high performance liquid chromatography coupled to photodiode array and mass spectrometry detectors (HPLC-PDA-MS). A specific and sensitive stability-indicating assay method for the simultaneous determination of the drug actarit, its process related impurities and degradation products was developed and validated.