The purpose of this study is to investigate whether V158866 is safe when given to healthy male subjects in single and multiple doses.

A first in human study:

To evaluate the safety and tolerability of single and multiple doses of V158866 in healthy male subjects To assess the pharmacokinetics (PK) of V158866 in healthy male subjects To assess the pharmacodynamics (PD) of V158866 by determining whether V158866 inhibits fatty acid amide hydrolase (FAAH ) in healthy male subjects

Inclusion Criteria:

Subjects must:

• be healthy male subjects aged 18 to 45 years inclusive
• Have a body mass index (BMI) between 19 and 30 kg/m2 inclusive
• be able to provide a semen sample
• be willing to use an effective method of contraception (see Section 6.1) for the duration of the study and for 4 months after the last dose of study medication
• be able to comply with the requirements of the entire study
• give written informed consent

Exclusion Criteria:

Subjects must not:

• intend to father a child with their female partner or through sperm donation within 4 months after the last dose of study medication
• have had a vasectomy
• have a significant medical condition or a history of such a condition that the Investigator considers should exclude the subject from the study
• have multiple drug allergies or be allergic to any of the components of V158866 study medication or its matching placebo (see Section 7)
• have smoked more than 5 cigarettes per day in the 6 calendar months before study drug administration
• consume more than 28 units of alcohol per week, or have a significant history of alcohol abuse
• have a positive test for alcohol or drugs of abuse at screening or admission to any of the dosing sessions
• have donated blood or plasma in excess of 500 mL within 4 months before study drug administration
• have been exposed to any new investigational agent within 3 months before study drug administration
• have clinically relevant abnormal findings on vital signs
• have clinically significant abnormalities on laboratory screening tests
• have clinically relevant abnormal physical findings on examination
• have clinically relevant abnormal findings on 12-lead ECG
• have a mean QTc corrected using Bazett's correction (QTcB) at screening >430 msec (from 3 supine ECGs, performed at least 5 minutes apart)
• be seropositive for hepatitis B, hepatitis C or HIV viruses at screening
• have any medical or social reasons for not participating in the study raised by their General Practitioner/primary care physician
• have any other condition that might increase the risk to the individual or decrease the chance of obtaining satisfactory data, as assessed by the Investigator
• have had treatment with any prescription medicine within one month or any over-the-counter medicines, except for paracetamol, within one week before study drug administration