Quantification of Drospirenone- and Ethinyl Estradiol-Related Impurities in a Combined Pharmaceutical Dosage Form by a Chromatography Method With a QbD Robustness Study.

Abstract

The estimation of drugs containing drospirenone (DRSP) and ethinyl estradiol (EE), and their related impurities, in low-dose oral contraceptive drug products is an extremely challenging target. The proposed research sought to develop and validate a stability-indicating method for quantifying drug substances and their related impurities in tablet formulation. To develop and validate a simple, specific, accurate, precise, and stability-indicating reverse-phase (RP)-HPLC method for quantification of DRSP, EE, and their impurities in accordance with International Conference on Harmonisation (ICH) guidelines. The separation was achieved using an Agilent Zorbax SB C18 column (4.6 mm × 250 mm, 5 µm) with a detection wavelength of 215 nm and mobile phases A (100% acetonitrile) and B (acetonitrile-water, 1 + 3, v/v) at a flow rate of 1.3 mL/min and a column temperature of 40°C. The recovery study of each impurity was conducted in the range of 24 to 72 µg/mL for DRSP-related impurities and 0.2 to 0.6 µg/mL for EE-related impurities with respect to the specification limit. A linearity study was conducted over a range of 1.5 to 90 µg/mL for DRSP and DRSP-related impurities, and 0.125 to 0.75 µg/mL for EE-related impurities. A Quality by Design (QbD) study demonstrated the method's robustness. As per current guidelines, a stability-indicating method has been developed for the determination of impurities in DRSP/EE film-coated tablets. A QbD-based robustness test was performed and the method was found to be robust. An accurate, precise, stability-indicating, gradient RP-HPLC method has been developed and validated to determine DRSP, EE, and nine related impurities in tablet formulation. A QbD technique was used to establish a robustness study.