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

Inclusion Criteria: * Males or females, ages 18-55 years, inclusive, in good general health. * Body mass index (BMI) within the range of 18.0 to 34.0 kg/m2, inclusive, and a minimum weight of 50.0 kg. * Current opioid users who have used opioids for recreational (non-therapeutic) purposes (i.e., for psychoactive effects) at least 10 times in the past year and have used opioids at least once in the 12 weeks before Screening. * Must not be physically dependent on opioids, as demonstrated by successful completion of the Naloxone Challenge Test. * Must meet Drug Discrimination Test (Qualification Phase) eligibility criteria. * Female subjects must have a negative serum pregnancy test at Screening and a negative urine pregnancy test at admission to Visit 2. Post-menopausal women (i.e., no menstrual period for at least one year) must have a follicle-stimulation hormone (FSH) level \>40 milli-international unit (mIU)/mL at Screening. * Female subjects of child-bearing potential must use an acceptable method of contraception, including abstinence from heterosexual intercourse, hormonal contraceptives, intrauterine device (IUD) with or without hormones, or double-barrier method (e.g., condom and spermicide), for 30 days prior to Screening, during the study and for 30 days following the last administration of study drug. * Female subjects of non-childbearing potential should be surgically sterile (i.e., have undergone complete hysterectomy, bilateral oophorectomy or tubal ligation) or…