Eur J Clin Pharmacol 1998 Jun;54(4):337-40
The effect of grapefruit juice on the pharmacokinetics of orally administered verapamil.
Zaidenstein
R, Dishi V, Gips M, Soback S, Cohen N, Weissgarten J, Blatt A, Golik A.
OBJECTIVE: To investigate the effect of grapefruit juice (GJ) on the
pharmacokinetics of orally administered verapamil in hypertensive patients.
METHODS: Ten hypertensive patients on chronic verapamil treatment participated in a two-day study. On day 1 200 ml of water was given 1 hour before, and together with the morning verapamil dose; on the day 2, water was replaced by GJ in the same order. Serial blood samples were collected and the concentrations of verapamil and its main dealkylated metabolite (D-617) were determined by high-performance liquid chromatography (HPLC). The area under the concentration versus time curve of verapamil (AUCv) and its metabolite D-617 (AUCM) were calculated before and after GJ ingestion. The peak serum concentration (Cmax) and the time until its appearance (tmax) were also determined.
RESULTS: GJ did not affect Cmax, tmax, AUCv or AUVm. The AUCv/AUCm ratio (AUCR) was slightly, but significantly, increased after GJ (1.67 vs 1.92).
CONCLUSIONS: A single administration of GJ with short-acting verapamil has no significant effect on the pharmacokinetics, of verapamil.