Effects of grapefruit juice on pharmacokinetic exposure to indinavir in HIV-positive subjects

The objective of this study was to determine the effects of double-strength grapefruit juice on gastric pH and systemic bioavailability of indinavir in HN-infected subjects receiving indinavir. Fourteen HN-infected subjects took 800 mg of indinavir with 6 ounces (180 mi) of water or double-strength grapefruit juice. Gastric pH was measured and blood samples were collected for 5 hours after indinavir dosing. Grapefruit juice increased the mean gastric pH (from 1.39 +/- 0.4 to 3.20 +/- 0.3; p < 0.05) and slightly delayed the absorption of indinavir (t(max) increased from 1.12 +/- 0.8 h to 1.56 +/- 0.6 h; p < 0.05). However, there were no significant differences in indinavir exposure. C,, was 16.7 +/- 7.3 muM with water versus 13.9 +/- 4.2 muM with grapefruit juice (p = NS), and AUC(0.8) was 37.5 +/- 19 with water versus 36.9 +/- 15 with grapefruit juice (p = NS). The authors concluded that concomitant administration of grapefruit juice increases gastric pH and delays indinavir absorption but does not uniformly affect the systemic bioavailability of indinavir in HN-infected subjects. (C) 2001 the American College of Clinical Pharmacology.