Development and validation of a RP-UPLC method for the determination of betamethasone dipropionate impurities in topical formulations using a multivariate central composite design.

The current study presents a specific, accurate, simple, and rapid UPLC method for the determination of impurities present in cream and ointment formulations of betamethasone dipropionate (BMD). The analytical method was optimized using central composite design (CCD) prior to the method validation. Critical Process Parameters (CPPs) and Critical Quality Attributes (CQAs) were identified for the analytical method. A total of 17 experiments were carried out and verified the individual and interaction effects of CPPs. The CPPs were optimized using a numerical method by keeping the CQAs within the desired range (R1-R2: minimize & R3-R5: maximize) as an optimization goal. Optimized chromatographic separation was achieved using a Waters Acquity UPLC BEH C18, 100 mm × 2.1 mm, 1.7 µm column with a gradient mode of elution comprising 20 mM phosphate buffer: ACN 70 : 30, v/v as mobile phase-A and 20 mM phosphate buffer: ACN 30 : 70, v/v as mobile phase-B. The developed method was validated in accordance with ICH guidelines. The validation data conclude that the developed method is specific, accurate, linear, precise, rugged, and robust for the quantification of impurities in BMD topical formulations.

A validated stability-indicating LC method for acetazolamide in the presence of degradation products and its process-related impurities.

The objective of the current study was to develop a validated, specific and stability-indicating reverse phase liquid chromatographic method for the quantitative determination of acetazolamide and its related substances. The determination was done for an active pharmaceutical ingredient, its pharmaceutical dosage form in the presence of degradation products, and its process-related impurities. The drug was subjected to stress conditions of hydrolysis (acid and base), oxidation, photolysis and thermal degradation as per International Conference on Harmonization (ICH) prescribed stress conditions to show the stability-indicating power of the method. Significant degradation was observed during acid and base hydrolysis, and the major degradant was identified by LC-MS, FTIR and (1)H/(13)C NMR spectral analysis. The chromatographic conditions were optimized using an impurity-spiked solution and the generated samples were used for forced degradation studies. In the developed HPLC method, the resolution between acetazolamide and, its process-related impurities (namely imp-1, imp-2, imp-3, imp-4 and its degradation products) was found to be greater than 2. The chromatographic separation was achieved on a C18, 250mmx4.6mm, 5microm column. The LC method employed a linear gradient elution, and the detection wavelength was set at 254nm. The stress samples were assayed against a qualified reference standard and the mass balance was found to be close to 99.6%. The developed RP-LC method was validated with respect to linearity, accuracy, precision and robustness.