This is a 3 part, phase 1 crossover study in healthy subjects to evaluate the pharmacokinetic profile of KVD824 following single and multiple doses of novel KVD824 modified-release formulations compared with a reference KVD824 immediate release formulation.

Part 1 of the study was a single-centre, open-label, non-randomised, 6-period crossover study designed to investigate the PK and safety of KVD824 MR prototype formulations (with or without an additional KVD824 IR capsule) compared to a reference KVD824 IR capsule formulation in healthy male and female subjects. Part 2 was an optional part designed to investigate the PK and safety of a selected KVD824 MR prototype tablet formulation (with or without an additional KVD824 IR capsule) in healthy male and female subjects in both the fed and fasted state. Note: this Part was not conducted as sufficient information on food effect was collected in the other Parts of the study.

Part 3 was a single-centre, randomised, double-blind, placebo-controlled, multiple dose group study to investigate the PK and safety of a selected KVD824 MR prototype tablet formulation (with or without an additional KVD824 IR capsule) in healthy male and female subjects. Part 3 started following completion of Part 1.

Inclusion Criteria:

1. Healthy males or non-pregnant, non-lactating healthy females.
2. Aged 18 to 55 years, inclusive at the time of signing informed consent.
3. Body mass index (BMI) of 18.0 to 32.0 kg/m2 as measured at screening.
4. Must be willing and able to communicate and participate in the whole study.
5. Must provide written informed consent.
6. Must agree to adhere to the contraception requirements.

Exclusion Criteria:

1. Subjects who have received any IMP in a clinical research study within the 90 days prior to Day 1.
2. Subjects who are study site employees, sponsor employees, or immediate family members of site or sponsor employees.
3. Subjects who have previously been administered IMP in this study. Subjects who have taken part in one part of this study are not permitted to take part in any other study part.
4. History of any drug or alcohol abuse in the past 2 years.
5. Regular alcohol consumption in males >21 units per week and females >14 units per week (1 unit = ½ pint beer, or a 25 mL shot of 40% spirit, 1.5 to 2 Units = 125 mL glass of wine, depending on type).
6. A confirmed positive alcohol breath test at screening or admission.
7. Current smokers and those who have smoked within the last 12 months. A confirmed breath carbon monoxide reading of greater than 10 ppm at screening or admission.
8. Current users of e-cigarettes and nicotine replacement products and those who have used these products within the last 12 months.
9. Females of childbearing potential who are pregnant or lactating (all female subjects must have a negative serum pregnancy test at screening and urine pregnancy test on admission).
10. Subjects with pregnant or lactating partners.
11. Subjects who do not have suitable veins for multiple venepunctures/cannulation as assessed by the investigator or delegate at screening.
12. Clinically significant abnormal clinical chemistry, haematology, coagulation or urinalysis as judged by the investigator. Subjects with Gilbert's Syndrome are allowed.
13. Confirmed positive drugs of abuse test result.
14. Positive hepatitis B surface antigen (HBsAg), hepatitis C virus antibody (HCV Ab) or human immunodeficiency virus (HIV) antibody results.
15. Evidence of renal impairment at screening, as indicated by an estimated creatinine clearance of <70 mL/min using the Cockcroft-Gault equation.
16. History of clinically significant cardiovascular, renal, hepatic, chronic respiratory or gastrointestinal disease, neurological or psychiatric disorder, as judged by the investigator.
17. Subjects with a history of cholecystectomy or gall stones.
18. Serious adverse reaction or serious hypersensitivity to any drug or the formulation excipients.
19. Presence or history of clinically significant allergy requiring treatment, as judged by the investigator. Hay fever is allowed unless it is active.
20. Donation or loss of greater than 400 mL of blood within the previous 3 months.
21. Subjects who are taking, or have taken, any prescribed or over-the-counter drug or herbal remedies (other than up to 4 g of paracetamol per day, HRT or hormonal contraception) in the 14 days before IMP administration.
22. Failure to satisfy the investigator of fitness to participate for any other reason.

Initial open-label crossover (Part 1) followed by double-blind, randomised, placebo-controlled part (Part 3).