title: Duration of effect of grapefruit juice on the pharmacokinetics of the CYP3A4 substrate simvastatin.
abstract: BACKGROUND
  Grapefruit juice is a potent inhibitor of CYP3A4-mediated drug metabolism. We wanted to investigate how long the inhibitory effect of grapefruit juice lasts, with the CYP3A4 substrate simvastatin used as a model drug.
  
  
  METHODS
  This crossover study consisted of 5 study days, during which 10 healthy volunteers ingested 40 mg simvastatin with water (control), with "high-dose" grapefruit juice (200 mL double-strength grapefruit juice three times a day for 3 days), or 1, 3, and 7 days after ingestion of "high-dose" grapefruit juice. For safety reasons, the study was performed in three parts to allow simvastatin-free days between the study days. Serum concentrations of simvastatin and simvastatin acid were measured by liquid chromatography-tandem mass spectrometry up to 12 hours.
  
  
  RESULTS
  When simvastatin was taken with grapefruit juice, the mean peak serum concentration (Cmax) and the mean area under the serum concentration-time curve [AUC(0-infinity)] of simvastatin were increased 12.0-fold (P < .001) and 13.5-fold (P < .001), respectively, compared with control. When simvastatin was administered 24 hours after ingestion of the last dose of grapefruit juice, the Cmax and AUC(0-infinity) were increased 2.4-fold (P < .01) and 2.1-fold (P < .001), respectively, compared with control. When simvastatin was given 3 days after ingestion of grapefruit juice, the Cmax and AUC(0-infinity) were increased 1.5-fold (P = .12) and 1.4-fold (P = .09), respectively, compared with control. Seven days after ingestion of grapefruit juice, no differences in the Cmax or AUC(0-infinity) of simvastatin were seen. The mean Cmax and AUC(0-infinity) of simvastatin acid were increased 5.0-fold and 4.5-fold, respectively (P < .001), compared with control when simvastatin was taken with grapefruit juice and 1.7-fold (P < .01) when it was taken 24 hours after ingestion of grapefruit juice. After an interval of 3 or 7 days between ingestion of grapefruit juice and simvastatin, the pharmacokinetic variables of simvastatin acid did not differ significantly from those in the control phase.
  
  
  CONCLUSIONS
  When simvastatin is taken 24 hours after ingestion of "high-dose" grapefruit juice, the effect of grapefruit juice on the AUC of simvastatin is only about 10% of the effect observed during concomitant intake of grapefruit juice and simvastatin. The interaction potential of even high amounts of grapefruit juice with CYP3A4 substrates dissipates within 3 to 7 days after ingestion of the last dose of grapefruit juice.
authors.affiliation: Department of Clinical Pharmacology, University of Helsinki and Helsinki University Central Hospital, Finland.
authors.forename: J J
authors.initials: JJ
authors.lastname: Lilja
authors.forename: K T
authors.initials: KT
authors.lastname: Kivistö
authors.forename: P J
authors.initials: PJ
authors.lastname: Neuvonen
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000704:Analysis of Variance; D019540:Area Under Curve; D001628:Beverages; D002957:Citrus; D018592:Cross-Over Studies; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004334:Drug Administration Schedule; D005260:Female; D018565:Food-Drug Interactions; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D000960:Hypolipidemic Agents / Q000493:pharmacokinetics; D008297:Male; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D012016:Reference Values; D019821:Simvastatin / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D013997:Time Factors
chemical_list: D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D000960:Hypolipidemic Agents; D003577:Cytochrome P-450 Enzyme System; D019821:Simvastatin; D006899:Mixed Function Oxygenases; C104464:CYP3A protein, human; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human