Clinical Study to Investigate Safety and Effects on Heart Rate, Blood Pressure, and Pharmacokinetic Interactions of ACT-334441

Single-center, Open-label, Randomized, Multiple-dose, Parallel-group Study to Investigate Safety and Effects on Heart Rate, Blood Pressure, and Pharmacokinetic Interactions of ACT-334441 Combined With Calcium-channel Blocker (Diltiazem) or Beta-blocker (Atenolol) Treatment in Healthy Subjects

The aim of the study is to investigate the safety of the concomitant administration of ACT-334441 with cardiovascular drugs.

The study will consist of two parts: a pilot part (Part A) that will be completed prior to the start of the main part (Part B). The Subjects who will participate in Part A are excluded from Part B.

Inclusion Criteria:

• Signed informed consent
• Body mass index (BMI) between 18.0 and 30.0 kg/m2 (inclusive) at screening.
• Women of childbearing potential must have a negative pregnancy test and they must use reliable methods of contraception
• Healthy on the basis of physical examination,cardiovascular assessments and laboratory tests

Exclusion Criteria:

• Pregnant or lactating women
• Any contraindication to the study drugs
• History or presence of any disease or condition or treatment, which may put the subject at risk of participation in the study or may interfere with the absorption, distribution, metabolism or excretion of the study drugs
• Any clinically significant abnormalities in laboratory tests, vital signs, ECG variables and pulmonary variables
• Any circumstances or conditions, which, in the opinion of the investigator, may affect the subject's full participation in the study or compliance with the protocol