Simultaneous determination of lamivudine and stavudine in antiretroviral fixed dose combinations by first derivative spectrophotometry and high performance liquid chromatography

Two methods are described for the simultaneous determination of lamivudine (3TC) and stavudine (d4T) in combined pharmaceutical tablets. The first method depends on first derivative UV-spectrophotometry with zero-crossing measurement technique. The first derivative absorbances at 280 and 300 nm were selected for the determination of stavudine and lamivudine, respectively. The second method is based on the separation of both drugs by high performance liquid chromatography using methanol:water (20:80) as the mobile phase at 0.6 ml/min on a reverse phase column with detection at 270 nm. Both the methods showed good linearity, reproducibility and precision. No spectral or chromatographic interferences from the tablet excipients were found. The proposed methods were suitably applied to the assay of commercial formulations. The procedures were rapid, simple and suitable for routine quality control application.