Chromatographic and immunochemical approaches to the analysis of the HIV protease inhibitor saquinavir in plasma

The development of the HIV protease inhibitor saquinavir (Ro 31-8959) requi red a range of analytical methods for its measurement in biological fluids. This paper describes the development of isocratic, reverse-phase HPLC/UV m ethods for the routine measurement of plasma levels of the drug together wi th a more sensitive radioimmunoassay, The performance of the two assays is compared with that of an HPLC/MS/MS method previously published and has bee n shown to be satisfactory, with coefficients of variation of calibration s tandards and quality control samples within the usual outside limits of +/- 15%. The HPLC/UV method can be routinely applied for concentrations down to 10-20 ng/ml and a lower limit of quantification of 1 ng/ml from 1 mi of hu man plasma is possible. The radioimmunoassay was developed for the specific measurement of saquinavir concentrations in human, HIV-positive plasma sam ples and has a lower limit of quantification of 0.5-1.0 ng/ml, Some prelimi nary findings suggested that it might not be specific in rat plasma and no attempts have been made to quantify any nonclinical samples with this techn ique. If still greater sensitivity is required, recourse can be made to the HPLC/MS/MS assay. (C) 2000 Academic Press.