UPLC Method for Determination of Moxonidine and Its Degradation Products in Active Pharmaceutical Ingredient and Pharmaceutical Dosage Form

A simple, rapid, isocratic, stability-indicating reverse phase ultra-performance liquid chromatographic (RP-UPLC) method was developed and validated for the routine analysis of moxonidine in the presence of its degradation products in active pharmaceutical ingredient and pharmaceutical dosage forms. Forced degradation studies were performed according to the guidance of International Conference for Harmonization and were used to evaluate moxonidine intrinsic stability. The drug was subjected to acid, neutral and base hydrolysis as well as to oxidative, thermal and photolytic decomposition in both solution and solid state. The drug appeared to be unstable towards acid and base hydrolysis. To achieve desirable conditions for UPLC analysis, the method development was done with the assistance of experimental design and multivariate optimization methodology by means of Derringer's desirability function. Stress samples were analyzed according to the experimental plan for fractional factorial screening design and Box-Behnken optimization design. The chromatographic separation was achieved on a C-18 Hypersil Gold aq. column (100 mm x 2.1 mm, 1.9 mu m) with the mobile phase consisting of methanol-ammonium acetate buffer (10 mM, pH 3.43) mixture (0.9:99.1, v/v) pumped at a flow rate of 870 mu L min(-1) and detection wavelength of 255 nm. The UPLC-MS and UPLC-MS/MS analyses were further used to characterize the found degradation products. The validation of the proposed method was also performed considering selectivity, linearity, accuracy, precision, limit of detection and limit of quantification, and the results indicated that the method fulfilled all required criteria. The method was successfully applied to the analysis of commercial tablets.