The safety, tolerability, and pharmacokinetics of nalmefene at a single oral dose of 10 mg in healthy Japanese male subjects will be evaluated.

Inclusion Criteria:

• The subject is a Japanese male.
• The subject is able to read and understand the informed consent form (ICF).
• The subject has a body mass index (BMI) ≥ 19 kg/m2 and ≤ 25 kg/m2 at the screening visit.
• The subject has a resting pulse and heart rate (as read on the ECG) ≥ 45 bpm and ≤ 100 bpm at the screening visit.

Exclusion Criteria:

• The subject has taken any prescription drugs, over-the counter medications, vitamin supplements, or supplements containing St. John's Wort (Hypericum perforatum) within 2 weeks prior to Day 1.
• The subject has a significant history of alcohol abuse, defined as an alcohol intake greater than 21 units per week. (A unit of alcohol is defined as 250 mL of lager/beer, 100 mL of wine, or 25 mL of spirits.)
• The subject has taken any investigational products within 4 months prior to Day 1.