This is a Phase I, open-label (both participant and investigator know the name of the medication given at a certain moment) trial in 18 healthy female participants to investigate the effect of TMC435 at steady-state on the steady-state pharmacokinetics of ethinlyestradiol and norethindrone. Ethinylestradiol (35 µg) and norethindrone (1.0 mg) are the components of Ovysmen, which is a widely used oral contraceptive (OC). All subjects will receive OC therapy for 2 complete OC cycles. During the first cycle, participants will receive Ovysmen alone, once daily, for the first 21 days. An OC- free period is respected from Day22 till and including Day28. During the second OC cycle, participants will receive again Ovysmen once daily during the first 21 days plus TMC435 150 mg once daily as of Day12 till and including Day21. Next, a OC-free period from Day22 till and including Day28 is established. Full 24-hour PK profiles of ethinylestradiol and norethindrone will be determined at the last day of OC treatment of the first OC cycle (i.e. on Day21) and on the last day of OC treatment of the second OC cycle (i.e. Day21). Full 24-hour PK profile of TMC435 will be determined on Day21 of second OC cycle. Pharmacodynamic (how the body reacts on the drug) assessments of serum levels of progesterone, luteinizing hormone and follicle-stimulating hormone (these hormones are involved in ovulation and in preparation of the womb for a pregnancy) will be done on Day1, 19, 20 and 21 of both OC cycles. Safety and tolerability will be assessed during the study period and during follow up. Blood and urine safety samples, electrocardiogram (ECG) and vital signs (blood pressure and heart rate) will be taken at screening, Day1, Day21 and Day22 of each OC cycle, and at the follow-up visit about 5 to 7 days after last TMC435 intake. A physical examination will be performed at screening, Day1 and Day20 of each OC cycle, and at the follow-up visit about 5 to 7 days after last TMC435 intake. Participants are admitted to the unit on Day20 in the morning and are discharged on Day22, for both OC cycles.
