A Study to Evaluate the Oral Abuse Potential of PF614 in Non-Dependent Recreational Opioid Users (PF614-104)

The study will consist of 4 phases: Screening, Qualification, Treatment and Follow-up.

1. Screening Visit (Visit 1) The Screening Phase will be completed as an outpatient visit within 28 days of the Qualification Phase and will consist of a standard medical screen. 2. Qualification Phase (Visit 2) Within 28 days of a standard medical screening, eligible subjects will return to the clinical site as inpatients to complete the Qualification Phase (Visit 2). Upon admission to the clinical site, subjects will be interviewed and assessed for continued eligibility for the study. Subjects will check into the inpatient facility on Day -1.

The Qualification Phase will include a Naloxone Challenge Test to confirm that subjects are not opioid dependent and a Drug Discrimination Test to ensure that subjects can distinguish between the active control (oxycodone hydrochloride (HCl) immediate-release tablets 40 mg) and placebo.

Eligible subjects who meet Qualification Criteria will remain as inpatient until the Treatment Phase. Subjects who do not meet Qualification Criteria will be discharged after all post-dose assessments have been performed after the last study drug administration. The last study drug administration in the Qualification Phase and the first study drug administration of the Treatment Phase will be separated by a washout period of approximately 72 hours. 3. Treatment Phase (Visit 2-Continued)

The Treatment Phase will consist of 5 treatment periods. Subjects will receive each of the following 5 treatments (1 per treatment period) in a randomized, double-blind, crossover manner, following a fasting period of at least 8 hours: * Treatment A: PF614 50 mg * Treatment B: PF614 100 mg * Treatment C: PF614 200 mg * Treatment D: Oxycodone IR 40 mg * Treatment E: Placebo

Pharmacodynamic, pharmacokinetic and safety assessments will be conducted prior to dosing and for 24 hours after each study drug administration. Each study drug administration will be separated by a washout interval of approximately 120 hours. All subjects will remain in clinic for the duration of the Treatment Phase. Subjects will be discharged after all post-dose assessments are performed at End of Treatment (EOT), if considered medically suitable for discharge by the investigator. 4. Follow-up Visit (Visit 3) A follow-up visit will be conducted at 8 days (±2 days) after last study drug administration in the Treatment Phase or after early termination (EOS/ET) from the study.