Study to Compare Oxymorphone Extended-Release (Opana ER) Versus Oxycodone Controlled-Release (Oxycontin)

Inclusion Criteria: * Recreational opioid use. * At least 3 lifetime occasions of recreational use of an oral intact modified-release opioid product. * BMI within range of 19.0 to 29.9 kg/m2, inclusive, minimum weight of 50.0 kg at screening and Day 0 of treatment period 1 Exclusion Criteria: * Self-reported history of drug or alcohol dependence in the past 2 years or presence of drug or alcohol dependence in the past 12 months as defined by the DSM-IV, including subjects who have ever been in a drug rehabilitation program. * Unwillingness or inability to abstain from recreational drug use as required for the study. * History of acute asthma or other obstructive airway disease or any condition that may increase the risk for respiratory depression, judged as clinically significant by the investigator or designee. * History of neurologic conditions such as convulsive disorders or severe head injury, judged as clinically significant by the investigator or qualified designee. * History of Addison's disease, hypothyroidism, pancreatitis, prostatic hypertrophy, or urethral stricture. * Use of non-prescription or prescription medications or natural health products within 7 days prior to first drug administration in the qualification phase and throughout the study, unless in the opinion of the investigator or designee, the product will not interfere with the study procedures or data integrity or compromise the safety of the subject. * Uses of Monoamine oxidize inhibitors (MAOIs) within 14 days of first drug administration in the qualification phase and throughout the study. * Current consumption of greater than 20 cigarettes (or 2 cigars) per day or inability to abstain from smoking (or use of any nicotine-containing sub stance) for at least 14 hours.