DETERMINATION OF LAMIVUDINE/DIDANOSINE/SAQUINAVIR IN HUMAN SERUM USING CAPILLARY ZONE ELECTROPHORESIS

Abstract

The anti-HIV drug mixture of lamivudine (3TC), didanosine (ddI), and saquinavir was separated and quantitated in human serum with capillary zone electrophoresis. Serum samples were treated using a solid-phase extraction procedure. The effects of various factors, such as run buffer type, buffer concentration, and pH on the separation were investigated. The optimized resolution was achieved with a run buffer containing 100 nM N,N-dimethyloctylamine in 80 mM phosphate buffer (pH 2.5). An uncoated 52 cm (effective length 30 cm) × 50 μm ID fused-silica capillary operated at 30°C was used in the analysis with UV detection at 210 nm. Diltiazem was chosen as an internal standard. All analytes were separated within 10 min with a voltage of + 20 kV and a current around 30 μA. The method was validated over the range of 0.4–37.8 μg/mL for 3TC, 1.4–34 μg/mL for ddI and 0.5–24.4 μg/mL for saquinavir. Intra-day and inter-day accuracy was less than 13.7% and intra-day and inter-day precision was less than 13.3%. Extraction recoveries of all analytes from plasma were higher than 79%. The assay should be applicable for pharmacokinetic studies and routine monitoring of these drugs in serum.