Clinical Use of a Simultaneous HPLC Assay for Indinavir, Saquinavir, Ritonavir, and Nelfinavir in Children and Adults

Docosahexaenoic acid (DHA) inhibits saquinavir metabolism in-vitro and enhances its bioavailability in rats

This study investigated the effect of docosahexaenoic acid (DHA) on the metabolism of saquinavir by cytochrome P450 3A (CYP3A) in-vitro using rat liver microsomes and in-vivo using rats. DHA showed a concentration-dependent inhibition of in-vitro saquinavir metabolism with Km, Vmax and Ki values of 2.21 microM, 0.054 micromol h(-1) (mg protein)(-1) and 149.6 microM, respectively. After oral co-administration with 250 microg kg(-1) DHA, the bioavailability of saquinavir significantly increased approximately 4 fold (P < 0.01) without affecting the elimination half-life, as compared with the control. In contrast, oral administration of DHA did not affect the kinetic parameters of saquinavir administered intravenously. These results suggest that the inhibitory effect of DHA on saquinavir metabolism predominantly takes place in the gut and imply that DHA impairs the function of enteric, but not of hepatic, CYP3A. The pharmacokinetic interaction occurred only when DHA was taken simultaneously with oral administration of saquinavir. These results considered together with the lack of time-dependent saquinavir metabolism inactivation effects in-vitro, imply that the inhibitory effect of DHA is primarily reversible. It is concluded that DHA inhibited saquinavir metabolism in-vitro and enhanced the oral bioavailability of saquinavir in rats.

Conventional HPLC Method Used for Simultaneous Determination of the Seven HIV Protease Inhibitors and Nonnucleoside Reverse Transcription Inhibitor Efavirenz in Human Plasma

We developed a simple HPLC method for the simultaneous quantitative determination of seven HIV protease inhibitors: amprenavir (APV), atazanavir (ATV), indinavir (IDV), lopinavir (LPV), nelfinavir (NFV), ritonavir (RTV), saquinavir (SQV), and a nonnucleoside reverse transcription inhibitor, efavirenz (EFV). This method involves a rapid liquid-liquid drug extraction from plasma, the use of an isocratic elution on a reversed-phase C18 column, and an ultraviolet detection at a single wavelength (205 nm). The mobile phase consisted of 39% 50 mM phosphate buffer (pH 5.9), 22% methanol and 39% acetonitrile. Forty-eight samples could be measured in one day since the runtime of one sample is 30 min. The assay has been validated over a concentration range of 0.05 to 12.20 microg/ml for APV, 0.09 to 12.05 microg/ml for ATV, 0.05 to 12.01 microg/ml for IDV, 0.12 to 12.36 microg/ml for LPV, 0.18 to 12.20 microg/ml for NFV, 0.12 to 12.33 microg/ml for RTV, 0.12 to 12.06 microg/ml for SQV, and 0.05 to 12.17 microg/ml for EFV. Calibration curves were linear in the described concentration ranges. The average accuracy ranged from 97.2 to 106.8%. Both the interday and intraday coefficients of variation for all drugs tested were less than 8.5%. This method provides a simple, accurate, and precise method for the therapeutic drug monitoring of the seven protease inhibitors and EFV in clinical routine use.