抄録
Objectives: We investigated the effect of grapefruit juice (GFJ) on the pharmaco kinetics of the new nifedipine formulation, Adalat CR, which is a once-daily slow release (coat-core) tablet and is formulated to release nifedipine throughout the gastrointestinal tract.
Methods: Single doses of Adalat CR 20 mg and 40 mg were administered with 250 ml of GFJ (Kirin Tropicana® 100%, Kirin Beverage Corp.) or water to eight Japanese healthy young male volunteers using the 4-treatment and 4-period crossover method with a 7-day washout period between treatments. Plasma concentrations of nifedipine and its metabolites (pyridine-form: M-I), and urinary metabolites (M-II and M-III) were measured.
Results: After administration of Adalat CR 20 mg and 40 mg with GFJ, the plasma concentration of nifedipine increased especially at the first peak of Adalat CR, which shows a two-peak profile. Cmax and AUC were significantly increased by 59-80% and 13-23%, respectively and CL was significantly decreased by 12-19%. Cmax ratio of pyridine-form to nifedipine (M I/nifedipine) was significantly decreased. Adalat CR was well tolerated even after administration with GFJ. No clinically relevant changes by GFJ were observed in blood pressure or pulse rate.
Conclusion: Changes in the pharmacokinetics after Adalat CR with GFJ were to a smaller extent compared to other dihydropiridines which are known interact with GFJ, i. e. nisoldipine or felodipine. Increased plasma concentration after administration of Adalat CR with GFJ was within the safe range. A marked interaction of Adalat CR with GFJ was not found. However, since Cmax and AUC increased and CL decreased signifi cantly after the administration of Adalat CR with GFJ, it is recommendable to advise patients to avoid intake of GFJ when Adalat CR is administered.
