title: Erythromycin coadministration increases plasma atorvastatin concentrations.
abstract: The effect of erythromycin on the pharmacokinetics of atorvastatin, an inhibitor of HMG-CoA reductase, was investigated in 12 healthy volunteers. Each subject received a single 10 mg dose of atorvastatin on two separate occasions, separated by 2 weeks. Erythromycin (500 mg qid) was given from 7 days before through 4 days after the second atorvastatin dose. Atorvastatin concentrations were determined by an enzyme inhibition assay, which measured both atorvastatin and active metabolites. When erythromycin was coadministered with atorvastatin, mean Cmax and AUC(0-infinity) increased by 37.7% and 32.5%, respectively. Mean terminal half-life was similar following each atorvastatin dose. Possible mechanisms for this interaction include erythromycin inhibition of first-pass conversion of atorvastatin to inactive metabolites and erythromycin inhibition of P-glycoprotein-mediated intestinal or biliary secretion.
authors.affiliation: Department of Pharmacokinetics, Parke-Davis Pharmaceutical Research Division, Warner-Lambert Company, Ann Arbor, Michigan 48105, USA.
authors.forename: P H
authors.initials: PH
authors.lastname: Siedlik
authors.forename: S C
authors.initials: SC
authors.lastname: Olson
authors.forename: B B
authors.initials: BB
authors.lastname: Yang
authors.forename: R H
authors.initials: RH
authors.lastname: Stern
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D019540:Area Under Curve; D000069059:Atorvastatin; D004347:Drug Interactions; D004917:Erythromycin / Q000494:pharmacology*; D005260:Female; D006207:Half-Life; D006538:Heptanoic Acids / Q000097:blood*; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000097:blood / Q000493:pharmacokinetics*; D000960:Hypolipidemic Agents / Q000097:blood / Q000493:pharmacokinetics*; D008297:Male; D008875:Middle Aged; D011758:Pyrroles / Q000097:blood*
chemical_list: D000900:Anti-Bacterial Agents; D006538:Heptanoic Acids; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D000960:Hypolipidemic Agents; D011758:Pyrroles; D004917:Erythromycin; D000069059:Atorvastatin