Stress testing of crisaborole by a novel stability indicating RP-HPLC method

Abstract

An isocratic reverse phase high performance liquid chromatographic method has been developed for the determination of crisaborole (CRB), a novel non-steroidal topical phosphodiesterase-4-inhibitor. The analyte was separated on an Agilent eclipse XDB-C18 (3.0 × 150 mm, 3.5 µm) analytical column using water: acetonitrile (30: 70 v/v) as the mobile phase at a flow rate of 0.75 ml/min under ambient temperature and PDA detection at 254 nm. Added to this, several validation parameters were exercised on the developed HPLC method as per ICH guidelines. Method variables, viz., mobile phase flow rate (0.75 ± 0.1 ml/min) and percentage of organic modifier in mobile phase (70 ± 5%) were studied by a central composite design for testing the robustness of the proposed method. The method was found to be linear in the concentration range of 2–100 µg/ml (r2 = 0.999) and precise (RSD ˂ 2%) satisfying regulatory criteria. The method was found to be robust and ambiguity of worst result for certain responses still are acceptable and likely to occur due to the effect of extreme experimental conditions. Stress testing of CRB was carried out under acid, base, thermal, photolysis, peroxide and neutral conditions. Separation of the forced degradation products from the main analyte was accomplished using a gradient elution of the mobile phase consisting acetonitrile from 0 to 100% in water at a flow rate of 1.2 ml/min.