A simple, specific, accurate and precise reversed phase high performance liquid chromatography (RP-HPLC) method has been developed for the simultaneous estimation of lamivudine, didanosine and efavirenz in pharmaceutical dosage form. The chromatographic separation for lamivudine, didanosine and efavirenz was achieved with mobile phase containing water: tetrahydrofuran: acetonitrile (45.83: 20.83: 33.34 % v/v/v), Oyster BDS premium C18 (250 mm × 4.6 mm, 5 μm) analytical column in isocratic mode at room temperature and UV detection at 245 nm. The compounds were eluted at a flow rate of 1.15 ml min-1. The retention times of lamivudine, didanosine and efavirenz were found to be 2.01 ± 0.003, 3.01 ± 0.001 and 8.61 ± 0.002 min respectively. Different analytical performance parameters such as linearity, precision, accuracy, specificity, limit of detection (LOD), limit of quantification (LOQ), robustness and ruggedness were determined according to ICH guidelines. The linear dynamic ranges were obtained from 15-90, 12.5-75 and 30-180 μg mL-1 for lamivudine, didanosine and efavirenz respectively. The mean recoveries obtained for lamivudine, didanosine and efavirenz were 99.85, 99.78 and 99.94 % respectively. Limit of detection and quantification for lamivudine 0.61 and 1.85 μg mL-1, for didanosine 0.43 and 1.31 μg mL-1 and for efavirenz 0.65 and 1.97 μg mL-1 respectively. The developed method was free from interferences due to excipients present in formulation and it can be used for routine quality control analysis.
