Simultaneous high-performance liquid chromatographic determination of the antiretroviral agents amprenavir, nelfinavir, ritonavir, saquinavir, delavirdine and efavirenz in human plasma

This article describes a method for the simultaneous determination of four licensed HIV protease inhibitors (amprenavir, nelfinavir, saquinavir and ritonavir) and two novel non-nucleoside reverse transcriptase inhibitors (efavirenz and delavirdine) in human plasma in a single run. Plasma samples (500 μl) were treated by liquid–liquid extraction with methyl tert.-butyl ether. The compounds were separated by reversed-phase liquid chromatography on a C18 column with spectrophotometric detection at 260 nm. The method is linear over the specific ranges investigated, accurate (inaccuracy <11.7%) and showed intra-day and inter-day precision within the ranges of 0.9–7.0 and 1.9–8.8%, respectively. The six compounds were stable in plasma after 6 months of storage at −20°C and after five freeze–thaw cycles.