The study will be a comparative oral bioavailability study between GKT137831 capsules and tablets, together with an assessment of the impact of concomitant food intake on the relative bioavailability of GKT137831 tablets.

This will be a randomized three-way open cross-over study.

Inclusion Criteria:

1. Healthy male subject, aged 18 to 60 years inclusive;
2. Non-smoker subject or smoker of not more than 5 cigarettes a day ;
3. No history of alcohol or drug abuse
4. Body Mass Index (BMI) between 18 and 27 5 kg/m2 inclusive;
5. Considered as healthy after a comprehensive clinical assessment (detailed medical history and complete physical examination);
6. Signing a written informed consent prior to selection;

Exclusion Criteria:

1. Blood donation (including in the frame of a clinical study) within 2 months before administration;
2. General anaesthesia within 3 months before administration;
3. Presence or history of drug hypersensitivity, or allergic disease diagnosed and treated by a physician;
4. Inability to abstain from intensive muscular effort;
5. No possibility of contact in case of emergency;
6. Any drug intake (except paracetamol) during the last month prior to the first administration;
7. History or presence of drug or alcohol abuse (alcohol consumption > 40 grams / day);
8. Excessive consumption of beverages with xanthine bases (> 4 cups or glasses / day);
9. Positive Hepatitis B surface (HBs) antigen or anti Hepatitis C Virus (HCV) antibody, or positive results for Human Immunodeficiency Virus (HIV) 1 or 2 tests;
10. Positive results of screening for drugs of abuse;
11. Subject who, in the judgment of the Investigator, is likely to be non-compliant or uncooperative during the study, or unable to cooperate because of a language problem, poor mental development;
12. Exclusion period of a previous study;
13. Administrative or legal supervision;