Determination of nelfinavir, a potent HIV protease inhibitor, and its active metabolite M8 in human plasma by high-performance liquid chromatography with photodiode-array detection

We developed and characterized a high-performance liquid chromatographic as say for the determination of nelfinavir (NFV), a potent HN protease inhibit or, and its active metabolite M8 in human plasma. Extraction of the interna l standard, Ms and NFV from the plasma buffered at pH 9.5 was achieved by a liquid-liquid extraction with a mixture of methyl-tert.-butyl ether and he xane. Following two washes of the reconstituted sample with hexane, separat ion was achieved on an octadecylsilyl analytical column with a mobile phase containing 0.1 % trifluoroacetic acid-acetonitrile-methanol (51:46:5, v/v) . Detection was performed using an ultraviolet photodiode-array detector. T he signal was monitored at a wavelength of 220 nm, The assay was found to b e linear and has been validated over the concentration range of 25 to 3000 mu g/l for M8 and 25 to 6000 mu g/l for NFV, from 500 mu l of plasma. Recov eries were 98.9% (SD 8.9%), and 100.2% (SD 11.7%) for M8 and NFV, respectiv ely. Concentrations that gave a signal-to-noise ratio of three (15 mu g/l f or both M8 and NFV) were selected to determine the limit of detection. The lower limit of quantification (25 mu g/l for both M8 and NFV) was defined a s the concentration for which the relative standard deviation and the perce nt deviation from the nominal concentration were lower than 20%. (C) 1999 E lsevier Science BN. All rights reserved.