A Study of Two Macitentan Pediatric Formulations in Healthy Adult Participants

A Single-center, Open-label, Single-dose, Randomized, 2-way Crossover Phase 1 Study in Healthy Adult Participants to Assess the Relative Oral Bioavailability of Two Macitentan Pediatric Formulations

The purpose of this study is to assess the rate and extent of absorption of macitentan following administration of a single oral dose of macitentan formulated as final market image (FMI) (test), compared to macitentan as the clinical service formulation (CSF) under fasted conditions in healthy adult participants.

Inclusion Criteria:

• Healthy on the basis of physical examination, medical and surgical history collected at screening. If there are abnormalities, the participant may be included only if the investigator judges the abnormalities to be not clinically significant. This determination must be recorded in the participant's source documents and initialed by the investigator
• Systolic blood pressure (SBP) between 100 and 145 millimeters of mercury (mmHg) (inclusive) and diastolic blood pressure (DBP) between 50 and 90 mmHg (inclusive) at screening, preferably measured on the right arm, supine after 5 minutes of rest and standing after 3 minutes
• Twelve-lead electrocardiogram (ECG) with heart rate between 45 and 90 beats per minute (bpm) and without clinically relevant abnormalities, at the discretion of the investigator, measured after the participant is supine for at least 5 minutes, at screening
• Body weight not less than 50.0 kilograms (kg) and body mass index (BMI) between 18.5 and 30.0 kilograms per meter square (kg/m^2) (inclusive)
• All women must have a negative highly sensitive serum (beta-human chorionic gonadotropin [beta- hCG]) pregnancy test at screening and must have a negative urine pregnancy test on Day -1 of each intervention period

Exclusion Criteria:

• Known allergies, hypersensitivity, or intolerance to macitentan or drugs of the same class, or any excipients of the drug formulations
• Taken any disallowed therapies, concomitant therapy within 14 days (or longer, based on elimination half-life) before administration of study intervention in the first intervention period
• Received an investigational intervention (including investigational vaccines) or used an invasive investigational medical device within 30 days or 10 half-lives (whichever is longer) before study intervention intake in the first intervention period, or received a biological product within 3 months or 10 half-lives (whichever is longer) before study intervention intake in the first intervention period, or is currently enrolled in an investigational study
• Values of hepatic aminotransferase (alanine aminotransferase and/or aspartate aminotransferase) greater than (>) 1.5 * upper limit of normal at screening
• Positive results from the human immunodeficiency virus (HIV) (type 1 and 2) serology at screening