This study will determine the pharmacokinetics (PK) of [14c]-samidorphan in healthy male volunteers.

Inclusion Criteria:

• Body mass index (BMI) of greater than/equal to 19 and less than/equal to 32 kg/m^2 at screening (minimum weight of 50.0 kg)
• Generally good health
• Subjects must agree to reduce the risk of a female partner becoming pregnant during the study and for 30 days after the last dose of the study drug by abstinence from heterosexual relationships or use of a reliable contraceptive method
• Additional criteria may apply

Exclusion Criteria:

• Clinically significant illness within 30 days
• History of alcohol or opioid dependence, or positive urine toxicological screen for marijuana, cocaine, amphetamines, opioids, barbiturates, and benzodiazepines
• History of oral or gastrointestinal disease
• Irregular bowel or bladder function
• History of allergy or hypersensitivity to opioid medications or opioid antagonists (eg, naltrexone, naloxone)
• Current or pending legal charges or probation that would interfere with study conduct
• Use of alcohol within 24 hours prior to admission or urine positive test for alcohol at screening or admission
• Tobacco or nicotine use within 90 days
• Anticipated need for prescription medicines during the study period
• Additional criteria may apply