Simultaneous Estimation of Lamivudine, Didanosine and Efavirenz in Bulk and their Formulation by UPLC

Objectives: To develop a simple, rapid, reliable and precise RP-UPLC method for the simultaneous estimation of lamivudine, didanosine and efavirenz in bulk and its tablet dosage forms. Materials and Methods: The chromatographic separation was achieved by using Zorbax SB Cyano (150x4.6mm ID) 1.7µm column, isocratic mobile phase consists; Ammonium acetate Buffer pH 4.5: Acetonitrile (55:45) %v/v with a flow rate of 1.0 ml/min. The detection was carried out at 274 nm. The current method was validated according to the ICH guidelines for accuracy, precision, linearity, specificity, robustness and ruggedness. Results: The retention times obtained for lamivudine, didanosine and efavirenz were 2.584, 4.228 and 5.206 min respectively. The calibration curves of peak area versus concentration, were linear from 15-45μg/mL, 30-90μg/ mL and 20-60μg/mL for lamivudine, didanosine and efavirenz and had regression coefficient (R2) 0.999. Limit of detection were found to be 1.7, 3.3, 3.8 µg/ml and limit of quantification were found to be 5.1, 6.7, 11.5 µg/ ml respectively for lamivudine, didanosine and efavirenz. The % assay of the marketed dosage form was found to be 100.2, 100.4 and 100.6 for lamivudine, didanosine and efavirenz. Conclusion: The experimental study results revealed the suitability of proposed method that can be used for simultaneous estimation of lamivudine, didanosine and efavirenz in bulk and their pharmaceutical formulations for routine quality control analysis.