Effect of African Potato (Hypoxis Hemerocallidea) on the Pharmacokinetics of Efavirenz

Abstract

Purpose: The purpose of this study was to evaluate the effect of African Potato (AP) on the pharmacokinetics of efavirenz (EFV). Methods: A single dose, two-phase sequential study was conducted over a period of 31 days in 10 healthy volunteers. On day 1 of the study volunteers were administered a 600 mg EFV tablet and blood samples were collected before dosing and at 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 5.0, 6.0, 8.0, 12.0, 18.0, 24.0, 36.0 and 48 hrs post dosing. From day 16, a traditionally prepared AP decoction was administered daily until day 30. On day 29, volunteers were administered a single 600 mg dose of EFV as was done on day 1. Plasma samples were harvested immediately after blood sample collection and frozen at -80 ºC until assayed. Plasma concentrations of EFV were determined by a validated HPLC method with UV detection and pharmacokinetic parameters were calculated. Geometric mean ratios of Cmax and AUC0-48 of EFV before and after co-administration of 14 successive daily doses of AP were compared. Results: All subjects completed the study and the geometric mean ratios of Cmax and AUC0-48 were 97.30 and 102.82 with corresponding 90% confidence intervals (CIs) of 78.81-120.14 and 89.04-118.80, respectively. Conclusions: Pharmacokinetic data generated during this study indicated that African Potato did not significantly alter the pharmacokinetics of EFV. Hence, co-administration of AP is unlikely to affect the clinical use of EFV.