This study will consists of 2 parts (Part 1 and 2) which will be sequentially conducted in 2 separate panels of 24 healthy adult Japanese participants each, at a single center. Part 1 is a double-blind (neither physician nor participant knows the treatment that the participant receives), placebo-controlled (placebo is compared with the study medication to test whether the study medication has a real effect in clinical study), randomized (study medication is assigned by chance), single ascending dose study to investigate the safety, tolerability, and pharmacokinetics of GSK2336805 in participants. It will consist of a screening phase, a treatment phase, and a follow-up phase. The maximum study duration for each participant will be approximately 5 weeks (including screening and follow-up phase). 24 participants will be equally divided in 3 cohorts with 8 participants in each cohort. In each cohort, participants will be randomly assigned to receive either a single oral dose of GSK2336805 (6 participants) or placebo (2 participants). Part 2 is an open-label (all people know the identity of the intervention), randomized, 4-way crossover study (method used to switch patients from one treatment arm to another in a clinical study) to investigate the potential pharmacokinetic drug-drug interactions between TMC435 and GSK2336805 at steady-state, and to evaluate the short-term safety and tolerability when TMC435 and GSK2336805 are co-administered in participants. It will consist of a screening phase, a treatment phase (4 treatment sessions [Treatment A, B, C, and D]), and a follow-up phase. The maximum study duration for each participant will be approximately 12 weeks (including screening and follow-up phase). During 4 treatment sessions, each of the 24 participants will receive Treatment A, B, C and D consecutively in different sequences with a washout period of at least 7 days between consecutive treatment sessions in each individual participant. Safety will be evaluated by assessing adverse events, clinical laboratory tests, electrocardiogram, vital signs, physical examination, alcohol breath tests, and specific toxicities.
The purpose of the study is to investigate the safety, tolerability, and pharmacokinetic (what the body does to a medication) of GSK2336805 alone and with the co-administration of TMC435 in healthy Japanese participants.