Pharmacokinetics of fingolimod (FTY720) and a combined oral contraceptive coadministered in healthy women: drug-drug interaction study results

Abstract

Fingolimod has a novel mechanism of action in multiple sclerosis, being a first-in-class sphingosine 1-phosphate receptor modulator. Because of a potential risk of fetal toxicity based on animal studies, women of childbearing potential are advised to take effective contraceptive measures during and for 2 months after stopping fingolimod therapy. To assess whether the efficacy of a combined oral contraceptive (OC) could be compromised during fingolimod therapy, a steady-state, drug-drug interaction study of fingolimod with ethinylestradiol/levonorgestrel was performed in healthy female volunteers. To assess the interaction between fingolimod 0.5 mg once daily and ethinylestradiol 30 μg/ levonorgestrel 150 μg once daily at a steady state. 31 healthy women received the combined OC only on Days 1 - 14, followed by OC plus fingolimod on Days 15 - 28. In the presence of fingolimod, ethinylestradiol pharmacokinetics were unchanged, and levonorgestrel maximum plasma concentration at steady state and area under the concentration-time curve during a dosing interval increased by factors of 1.10 (90% CI 1.05 - 1.16) and 1.22 (90% CI 1.18 - 1.27), respectively. Fingolimod therapy does not alter the pharmacokinetics of the combined OC ethinylestradiol/ levonorgestrel to a clinically significant degree. Ethinylestradiol/levonorgestrel does not alter the pharmacokinetics of fingolimod. Women receiving fingolimod therapy are able to use a combined OC as a means of effective birth control.