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Grapefruit juice enhances the bioavailability of the HIV protease inhibitor saquinavir in man
Author(s) -
Kupferschmidt Hugo H. T.,
Fattinger Karin E.,
Ha Huy Riem,
Follath Ferenc,
Krähenbühl Stephan
Publication year - 1998
Publication title -
british journal of clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.216
H-Index - 146
eISSN - 1365-2125
pISSN - 0306-5251
DOI - 10.1046/j.1365-2125.1998.t01-1-00687.x
Subject(s) - saquinavir , bioavailability , grapefruit juice , pharmacology , pharmacokinetics , oral administration , chemistry , cyp3a4 , volume of distribution , protease inhibitor (pharmacology) , medicine , biochemistry , human immunodeficiency virus (hiv) , viral load , metabolism , immunology , antiretroviral therapy , cytochrome p450
Aims Saquinavir is a potent HIV protease inhibitor whose effectiveness is limited in vivo by its low bioavailability. Since saquinavir is metabolized by CYP3A4, the effect of grapefruit juice, an inhibitor of CYP3A4, was investigated on its bioavailability.Methods After an overnight fast, eight healthy volunteers were treated with either 400 ml grapefruit juice or water before intravenous (12 mg) or oral saquinavir (600 mg) was administered. Serial blood samples were obtained over the following 24 h and standardized meals were served 5 and 10 h after the administration of saquinavir. The plasma concentrations of saquinavir were determined by high‐performance liquid chromatography and pharmacokinetic parameters were calculated by routine methods.Results The AUC was not affected by grapefruit juice after intravenous administration, but it increased significantly from 76±96 (water, mean (s.d.) to 114±70 (μg l −1 h (grapefruit juice) after oral saquinavir. Similarly, the oral bioavailability of saquinavir increased by a factor of 2 with grapefruit juice (from 0.7% to 1.4%). In contrast, clearance, volume of distribution and elimination half‐life of saquinavir were not affected by grapefruit juice. After oral, but not after intravenous administration, the plasma concentration‐time curve showed a second peak after lunch irrespective of pretreatment, suggesting enhancement of absorption by food.Conclusions The studies demonstrate that grapefruit juice increases the bioavailability of saquinavir without affecting its clearance, suggesting that inhibition of intestinal CYP3A4 may contribute. Since the antiretroviral effect of saquinavir is dose‐dependent, inhibition of CYP3A4 may represent a way to enhance its effectiveness without increasing the dose.