Simultaneous determination of HIV-protease inhibitors lamivudine and zidovudine in pharmaceutical formulations by micellar electrokinetic chromatography.

A micellar electrokinetic chromatographic (MEKC) method for the simultaneous separation and determination of lamivudine (LMV) and zidovudine (ZDV) in pharmaceutical formulation has been developed. Factors that affect the separation, such as buffer pH, surfactant concentration (sodium dodecyl sulfate, SDS), organic solvents and applied voltage were optimized. Buffer consisting of 12.5 mM sodium tetraborate decahydrate and 15 mM boric acid adjusted at pH 10.8, containing 90 mM SDS and 5% (v/v) acetonitrile (ACN) was found to be suitable for the separation of the drugs. p-Aminobenzoic acid (PABA) was used as internal standard (I.S.). Detection of analytes and I.S. was performed at a wavelength of 210 nm. It was observed that both the drugs and I.S. were migrated within 20 min at the applied voltage of +10 kV. Validation of the method was performed in terms of linearity, accuracy, precision, limit of detection (LOD) and quantification (LOQ). An excellent linearity was obtained in the concentration range 10-80 microg/ml for LMV and 10-100 microg/ml for ZDV. The detection limits for LMV and ZDV were found to be 2.5 and 2.0 microg/ml, respectively. The optimized method was applied to the simultaneous determination of LMV and ZDV in pharmaceutical formulation and human plasma (spiked) samples. Recovery of both the drugs in tablet dosage form and spiked drugs in plasma were > or =99.72% (relative standard deviation (R.S.D.)< or =1.84%) and > or =80.4% (R.S.D.< or =5.4%), respectively. In the electropherogram no interfering peaks were observed in the region of analytes and I.S. due to inactive ingredients in the tablets and matrices in plasma.