DEVELOPMENT AND VALIDATION OF AN REVERSE PHASE-HIGH PERFORMANCE LIQUID CHROMATOGRAPHY METHOD FOR THE SIMULTANEOUS DETERMINATION OF OLANZAPINE AND FLUOXETINE HYDROCHLORIDE IN TABLET DOSAGE FORM

Objectives: To develop and validate a novel reverse phase-high performance liquid chromatography (RP-HPLC) method for the simultaneous estimation of olanzapine and fluoxetine hydrochloride in a fixed-dose combination tablet formulation. Methods: Chromatographic separation was carried out on a Waters Symmetry C18 column (250 mm × 4.6 mm, 5 μm) using a mobile phase of phosphate buffer (pH 3.0) and acetonitrile in the ratio of 55:45 (v/v), delivered at a flow rate of 1.0 mL/min. Detection was performed at 235 nm using a ultraviolet detector. The method was validated in accordance with ICH Q2(R1) guidelines. Results: The method exhibited linearity over the concentration range of 2–12 μg/mL for olanzapine and 4–24 μg/mL for fluoxetine hydrochloride, with correlation coefficients (r2) of 0.999 for both drugs. Precision studies showed percentage relative standard deviation (%RSD) values below 1% for intra-day and inter-day measurements. Accuracy was confirmed by recovery studies, yielding average recoveries of 99.44% for olanzapine and 99.59% for fluoxetine hydrochloride. The method demonstrated robustness at lower flow rates, while sensitivity was observed at higher flow variations. Ruggedness studies showed %RSD values within acceptable limits. Assay of marketed tablets resulted in average assay values of 100.22% for olanzapine and 99.66% for fluoxetine hydrochloride. Conclusion: The developed RP-HPLC method is simple, precise, accurate, and suitable for routine quality control analysis of olanzapine and fluoxetine hydrochloride in combined dosage forms.