Quantitation of fluoxetine hydrochloride in capsules using high-performance liquid chromatography

A stability-indicating high-performance liquid chromatographic method for the quantitation of fluoxetine hydrochloride in capsules (the only dosage form available) has been developed. The method is accurate and precise with a percent relative standard deviation of 1.04 based on 6 readings. An excellent separation of fluoxetine from methyltestosterone (the internal standard) was achieved, and sharp peaks were obtained by adding acetic acid to the mobile phase. The inactive ingredients present in the capsule powder did not interfere with the assay procedure. The recovery of fluoxetine from the synthetic mixtures was quantitative. The drug appears to be very stable in the acidic medium and highly susceptible to degradation in the basic medium.