title: Interactions between simvastatin and troglitazone or pioglitazone in healthy subjects.
abstract: Two randomized, two-period crossover studies were conducted to evaluate the effects of repeat oral dosing of troglitazone (Study I) and pioglitazone (Study II) on the pharmacokinetics of plasma HMG-CoA reductase inhibitors following multiple oral doses of simvastatin and of simvastatin on the plasma pharmacokinetics of troglitazone (Study I) in healthy subjects. In both studies, each subject received two treatments. Treatment A consisted of once-daily oral doses of troglitazone 400 mg (Study I) or pioglitazone 45 mg (Study II) for 24 days with coadministration of once-daily doses of simvastatin 40 mg (Study I) or 80 mg (Study II) on Days 15 through 24. Treatment B consisted of once-daily oral doses of simvastatin 40 mg (Study I) or 80 mg (Study II) for 10 days. In Study I, the area under the plasma concentration-time profiles (AUC) and maximum plasma concentrations (Cmax) of HMG-CoA reductase inhibitors in subjects who received both troglitazone and simvastatin were decreased modestly (by approximately 30% for Cmax and approximately 40% for AUC), but time to reach Cmax (tmax) did not change, as compared with those who received simvastatin alone. Simvastatin, administered orally as a 40 mg tablet daily for 10 days, did not affect the AUC or tmax (p > 0.5) but caused a small but clinically insignificant increase (approximately 25%) in Cmax for troglitazone. In Study II, pioglitazone, at the highest approved dose for clinical use, did not significantly alter any of the pharmacokinetic parameters (AUC, Cmax, and tmax) of simvastatin HMG-CoA reductase inhibitory activity. For all treatment regimens, side effects were mild and transient, suggesting that coadministration of simvastatin with either troglitazone or pioglitazone was well tolerated. The modest effect of troglitazone on simvastatin pharmacokinetics is in agreement with the suggestion that troglitazone is an inducer of CYP3A. The insignificant effect of simvastatin on troglitazone pharmacokinetics is consistent with the conclusion that simvastatin is not a significant inhibitor for drug-metabolizing enzymes. The lack of pharmacokinetic effect of pioglitazone on simvastatin supports the expectation that this combination may be used safely.
authors.affiliation: Department of Drug Metabolism, Merck Research Laboratories, West Point, Pennsylvania 19486, USA.
authors.forename: T
authors.initials: T
authors.lastname: Prueksaritanont
authors.forename: J M
authors.initials: JM
authors.lastname: Vega
authors.forename: J
authors.initials: J
authors.lastname: Zhao
authors.forename: K
authors.initials: K
authors.lastname: Gagliano
authors.forename: O
authors.initials: O
authors.lastname: Kuznetsova
authors.forename: B
authors.initials: B
authors.lastname: Musser
authors.forename: R D
authors.initials: RD
authors.lastname: Amin
authors.forename: L
authors.initials: L
authors.lastname: Liu
authors.forename: B A
authors.initials: BA
authors.lastname: Roadcap
authors.forename: S
authors.initials: S
authors.lastname: Dilzer
authors.forename: K C
authors.initials: KC
authors.lastname: Lasseter
authors.forename: J D
authors.initials: JD
authors.lastname: Rogers
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000704:Analysis of Variance; D019540:Area Under Curve; D002839:Chromans / Q000009:adverse effects / Q000097:blood* / Q000494:pharmacology*; D016001:Confidence Intervals; D018592:Cross-Over Studies; D004334:Drug Administration Schedule; D004347:Drug Interactions; D005260:Female; D006261:Headache / Q000139:chemically induced; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000097:blood / Q000494:pharmacology*; D007004:Hypoglycemic Agents / Q000097:blood / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D000077205:Pioglitazone; D019821:Simvastatin / Q000009:adverse effects / Q000097:blood* / Q000494:pharmacology*; D013844:Thiazoles / Q000009:adverse effects / Q000097:blood* / Q000494:pharmacology*; D045162:Thiazolidinediones; D000077288:Troglitazone
chemical_list: D002839:Chromans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D007004:Hypoglycemic Agents; D013844:Thiazoles; D045162:Thiazolidinediones; D019821:Simvastatin; D000077288:Troglitazone; D000077205:Pioglitazone