Physicians might be concerned that Adempas may have a metabolic interaction with oral contraceptives (OC) that could decrease the contraceptive efficacy of the OC. The information regarding lack of potential pharmacokinetic interaction has been communicated; there is a need for more re-assurance and further data that there is no interaction between Adempas and OCs. A drug-drug interaction study of riociguat with an OC such as Microgynon in the least vulnerable population for these purposes, i.e. healthy postmenopausal women, is considered adequate to inform about safe use of Adempas with OCs.

Inclusion Criteria:

• Healthy female subject
• Non-smokers of at least 3 month before screening
• Age: 52 to 65 years (inclusive) at the first screening examination
• Ethnicity: white
• Body mass index (BMI)>=20 and <=32 kg/m2
• Postmenopausal state, defined as
• Medical history, if applicable (natural menopause at least 12 months before the first study drug administration and hormone analyses in serum
• Age<60 years: follicle-stimulating hormone (FSH) >40 IU/L in plasma
• Age <60 years: estradiol (E2) <20 ng/L (<73 pmol/L) in plasma

Exclusion Criteria:

• History of coronary artery disease, Symptomatic postural hypotension, History of bronchial asthma, known hypersensitivity to the study, relevant diseases within 4 weeks before study drug administration,
• Presence or a history of venous or arterial thrombotic / thromboembolic events or cerebrovascular accident, a high risk for venous or arterial thrombosis,
• Use of systemic or topical medicines or substances which oppose the study objectives, smoking, use of sex hormones in any forms
• Clinically relevant findings in the ECG, systolic blood pressure below 110 or above 145 mmHg, heart rate below 50 or above 95 beats per minute
• Clinically relevant findings in the gynecological examination,
• Participation in another clinical study