A Pharmacokinetic, Safety and Tolerability Study in Healthy Adult Males

Inclusion Criteria: * Healthy as determined by a responsible physician or trained qualified designee * Males: 18 - 55 years inclusive at screening * Capable of giving written informed consent Exclusion Criteria: * Clinically significant conditions or history of fainting or syncope * Medical or psychiatric illness that could interfere with the completion of treatment and follow up * Major surgery within 4-weeks of screening * Known difficulty with obtaining intravenous access * History of sensitivity to the study medication, or intolerance to opioids, or a history of medication or other allergy that contraindicates their participation * Use of prescription or non-prescription medications * History of excessive alcohol use * History of drug abuse within 6 months of screening * Use of any illegal drug within 30 days of screening and throughout participation in the study * History of smoking or use of nicotine containing products within 3 months of screening and throughout participation in the study * Donation of blood or plasma 4 weeks prior to dosing * Participation in a clinical trial and has received medication within 30 days * Weight \<50 kg or BMI outside range of 18-32 kg/m2 * Positive for HIV antibody, hepatitis B virus surface antigen, or hepatitis C virus * Unwillingness to abstain from sexual intercourse with a pregnant or lactating woman and, if engaging in sexual intercourse with a female partner of child-bearing potential, use a condom and spermicide, in addition to having their female partner use another form of contraception, and abstain from sperm donation