title: Pharmacodynamics and pharmacokinetics of oral contraceptives co-administered with alosetron (Lotronex).
abstract: The 5-HT3 receptor antagonist alosetron (Lotronex) is indicated for use in women with severe, chronic, diarrhea-predominant irritable bowel syndrome (IBS) who have failed conventional therapy. Oral contraceptives (OCs) and alosetron are potential co-medications in women of childbearing age. This study assessed the effect of alosetron co-administration on pharmacodynamic markers of contraceptive efficacy, on the pharmacokinetics of estrogen and progesterone OC components, and on the activity of biochemical markers for the risk of thrombosis. This was an open label, nonrandomized two-way crossover study in 18 healthy women stabilized for 3 months on a low-dose OC containing ethinyl estradiol (EE) and levonorgestrel (LN). Alosetron had no effect on serum concentrations of luteinizing hormone (LH) or follicle-stimulating hormone. Ovarian activity grades (assessing follicle size, progesterone, and 17beta-estradiol concentrations) were similar during OC use with and without alosetron. Steady-state (Day 21) AUC24, Cmax, and tmax of both LN and EE were similar during coadministration of alosetron with an OC. Concentrations and activity of biochemical markers of thrombosis risk were not different in the presence of alosetron. These results indicate that alosetron does not alter the pharmacokinetics or pharmacodynamic markers of efficacy for a low-dose combination OC. The results also suggest that thromboembolic risk is not increased when alosetron is co-administered with an OC.
authors.affiliation: Department of Clinical Pharmacology and Discovery Medicine, GlaxoSmithKline, Research Triangle Park, North Carolina 27709, USA. kevin.m.koch@gsk.com
authors.forename: Kevin
authors.initials: K
authors.lastname: Koch
authors.forename: Corinne
authors.initials: C
authors.lastname: Campanella
authors.forename: Charlotte A
authors.initials: CA
authors.lastname: Baidoo
authors.forename: Janet A
authors.initials: JA
authors.lastname: Manzo
authors.forename: Vanessa Z
authors.initials: VZ
authors.lastname: Ameen
authors.forename: Kathryn E E
authors.initials: KE
authors.lastname: Kersey
mesh_terms: D000328:Adult; D001779:Blood Coagulation Factors / Q000032:analysis; D002243:Carbolines / Q000494:pharmacology*; D003276:Contraceptives, Oral / Q000493:pharmacokinetics / Q000494:pharmacology*; D018592:Cross-Over Studies; D004347:Drug Interactions; D004997:Ethinyl Estradiol / Q000493:pharmacokinetics / Q000494:pharmacology; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D005765:Gastrointestinal Agents / Q000494:pharmacology*; D006801:Humans; D016912:Levonorgestrel / Q000493:pharmacokinetics / Q000494:pharmacology; D007986:Luteinizing Hormone / Q000097:blood; D010053:Ovary / Q000502:physiology
chemical_list: D001779:Blood Coagulation Factors; D002243:Carbolines; D003276:Contraceptives, Oral; D005765:Gastrointestinal Agents; C090840:alosetron; D004997:Ethinyl Estradiol; D016912:Levonorgestrel; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone