Study to compare the pharmacokinetics, safety and tolerability of the pediatric and adult branaplam formulation in healthy adults and the effect of food on the latter

INTERVENTION: This study will be an open‐label, randomized, single‐dose, two‐part, two‐period, cross‐over study in healthy participants. A total of approximately 32 participants will be recruited for the study. Part 1 (relative bioavailability study): a two‐period crossover, adult vs pediatric formulation fasted study In Part 1, 16 volunteers will receive an oral dose of the pediatric recipe in one period and the new adult recipe in another period, both when in a fasted state. Part 2 (food effect study): a two‐period crossover, adult formulation fed vs adult formulation fasted study In Part 2, 16 volunteers will receive an oral dose of the adult recipe of the test medicine in a fed state in one period and in a fasted state in another period. Participants will receive a single administration of 112 mg of the study drug on up to two separate occasions. Volunteers will be discharged from the clinical unit on Day 5 and will return to the clinic for three return visits on Day 8, Day 11 and Day 15 of each period. Volunteers will also receive a follow‐up phone call 30 days after the final dose. Blood and urine samples will be taken throughout the study for analysis of the test medicine and for their safety. In both study parts, volunteers are expected to be involved in this study for about 13 weeks from screening to the follow‐up call. CONDITION: Huntington's disease ; Nervous System Diseases ; Huntington disease PRIMARY OUTCOME: PK parameters calculated from levels of the drug in blood plasma and urine, assessed by a validated liquid chromatography‐mass spectrometry (LC‐MS/MS) method of samples collected on days 1, 2, 3, 4, 5, 8, 11, 15 SECONDARY OUTCOME: ; Safety measures (including vital signs, ECGs, safety laboratory parameters and adverse events [AEs]) in both study parts:; 1. Vital signs measured at screening, baseline, pre‐dose, days 1, 2, 3, 5, 8, 11, 15; 2. ECGs measured at screening, baseline, pre‐dose, days 1, 2, 3, 4, 5, 11, 15; 3. Safety laboratory parameters (blood/urine) measured at screening, baseline, pre‐dose, days 1, 2, 3, 4, 5, 8, 11, 15; 4. Adverse events measured at screening, baseline, pre‐dose, days 1, 2, 3, 4, 5, 8, 11, 15; INCLUSION CRITERIA: 1. Healthy male and non‐childbearing potential female participants, 18 to 60 years of age inclusive, and in good health as determined by past medical history, physical examination, vital signs, electrocardiogram, and laboratory tests at screening and baseline 1. 2. Participants must weigh at least 50 kg at screening to participate in the study, and must have a body mass index within the range of 18.0 to 30.0 kg/m² as measured at screening. Body mass index = body weight (kg) / [height (m)]². 3. At screening and baseline vital signs (systolic blood pressure, diastolic blood pressure and pulse rate) will be assessed in the supine position and again in the standing position (after at least 3 minutes in each position). Oral body temperature will also be taken with the other supine vital sign assessments. Supine vital signs must be within the following ranges at screening and baseline 1: 3.1. Ora