A Study to Evaluate ACT-132577 in Healthy Subjects and in People With Severe Kidney Disease

Inclusion Criteria: ALL SUBJECTS: * Signed informed consent in the local language prior to any study-mandated procedure; * Male/female aged 18 to 65 years (inclusive) at screening; * Body mass index of 18.0 to 32.0 kg/m2 (inclusive) at screening. Body weight at least 50 kg; * Women of childbearing potential must have a negative serum pregnancy test and use reliable birth controls up to 30 days after the end of study treatment. HEALTHY SUBJECTS: * Normal renal function confirmed by the estimated glomerular filtration rate (eGFR) determined at screening; * Healthy on the basis of physical examination, cardiovascular assessments and laboratory tests. SEVERE RENAL FUNCTION IMPAIRMENT SUBJECTS: \- Severe renal function impairment is defined by eGFR estimated at screening between 15 mL/min/1.73 m2 and 29 mL/min/1.73 m2 (inclusive). Exclusion Criteria: ALL SUBJECTS: * Pregnant or lactating women; * Known hypersensitivity to ACT-132577 or drugs of the same class, or any of their excipients; * Known hypersensitivity or allergy to natural rubber latex; * Any circumstances or conditions, which, in the opinion of the investigator, may affect full participation in the study or compliance with the protocol. SEVERE RENAL FUNCTION IMPAIRMENT SUBJECTS: * End-stage renal disease that requires dialysis; * Hemoglobin concentration \< 9 g/dL; * History of severe renal stenosis; * Serum potassium concentration \> 5.5 mmol/L; * Presence of severe cardiac disease; * History of clinically relevant bleeding disorder; * Presence of any organ disorder, with the exception of renal function impairment, or use of any medication which might interfere with the pharmacokinetics of ACT-132577; * Known life-threatening disease with a life expectancy of less than 1 year; * Presence of unstable diabetes mellitus.