This was a Phase I, single centre, open-label, non-randomised study and was designed to be conducted in up to 2 parts. The purpose of Part 1 was to identify a MR formulation of PCS499 that would provide an optimal dosing regimen in patients. The purpose of Part 2 of the study was to generate repeat dose information for the selected MR formulation of PCS499 in order to provide additional PK information for future patient studies.

Inclusion Criteria:

1. Male or non-pregnant, non-lactating female subjects
2. Aged 18 to 55 years, inclusive
3. Subjects who were healthy as determined by no clinically relevant abnormalities identified by a detailed medical history, full physical examination, vital signs, 12-lead resting electrocardiogram (ECG; corrected QT interval [QTc] ≤450, QRS <120, PR <220; normal morphology) performed at the screening visit and prior to each dosing
4. Body mass index (BMI) of 18.0 to 35.0 kg/m2 inclusive or, if outside the range, considered not clinically significant by the investigator and body weight >50 kg
5. Subjects who were willing and able to be confined at the clinical research centre for the scheduled inpatient visits
6. Ability to swallow multiple tablets whole

Exclusion Criteria:

1. Subject had a clinically significant history of GI, cardiovascular, musculoskeletal, endocrine, hematologic, psychiatric, renal, hepatic, bronchopulmonary, neurologic, immunologic, and/or lipid metabolism disorders and/or drug hypersensitivity
2. Subject had a known or suspected malignancy with the exception of basal cell carcinoma
3. Subject had a positive blood screen for human immunodeficiency virus (HIV), hepatitis B surface antigen (HBsAg), or hepatitis C virus antibody (HCV Ab) at the screening visit
4. Female subjects who were pregnant or lactating (all female subjects required a negative serum pregnancy test at the screening and a negative urine pregnancy test at each admission).
5. Subject had active disease or symptoms within 7 days prior to Day -1, such as nausea, vomiting, diarrhoea, and infection
6. Subject had undergone a hospital admission or major surgery within 30 days prior to the Screening visit
7. Subjects who had taken part in Part 1 were not permitted to take part in Part 2