Determination of ethinyl estradiol in solid dosage forms by high-performance liquid chromatography.

A rapid, reproducible high-performance liquid chromatographic system for the determination of ethinyl estradiol in solid dosage forms consisting of a reversed-phase column with a mobile phase of 0.05 M aqueous KH2PO4-methyl alcohol (2:3) and fluorescence detection has been developed. This stability-indicating method is applicable to tablets containing ethinyl estradiol alone or in combination with methyltestosterone and progesterones. The procedure has been used for the determination of ethinyl estradiol in single tablets, stability samples, and dissolution medium. Recovery of drug substance added to placebo was from 97.3 to 101.5% in stability and single-tablet assays, and 95.4 to 102.2% in dissolution assays. Reproducibility studies gave relative standard deviations of 0.4-2.2%.

High performance liquid chromatographic determination of clotrimazole in pharmaceutical formulations.

A simple stability-indicating high performance liquid chromatographic (HPLC) method has been developed which separates clotrimazole from impurities and decomposition products in bulk drugs, creams, tablets, and solutions. Average recovery data for drug substance added to placebos were: tablet, 99.8%; solution, 99.5%; and cream, 100.0%. Average reproducibilities (RSD) on drug substance and formulations were: drug substance, 1.3%; tablets, 1.8%; solutions, 1.1%; and creams, 0.6%. HPLC assay results for both fresh and degraded samples agree with USP XX titration assay results. The method allows for the simultaneous determination of (o-chlorophenyl)diphenylmethanol hydrolysis product impurity.