Single Dose Crossover Study to Compare the Respiratory Drive After Administration of Belbuca, Oxycodone and Placebo.

Inclusion Criteria: 1. Male or female subjects 18 to 55 years of age, inclusive. 2. Subjects are in good health as indicated by medical history, PE, vital signs, oxygen saturation, clinical laboratory tests, and 12-lead ECG. A status of good health will be defined by the absence of evidence of any clinically significant, active or chronic disease based on these assessments, in the opinion of the investigator. 3. Subjects with a body mass index (BMI) of 18.0 to 33.0 kg/m2, inclusive, and body weight greater than 50 kg, inclusive. 4. Subject is able to speak, read, and understand English and voluntarily provide written informed consent to participate in the study. 5. Subjects have healthy oral mucosa as determined by examination at screening and admission to the clinical facility. 6. Subject must be a recreational opioid user who is not currently dependent on opioids (based on self-reported DSM-5 criteria and a Clinical Opiate Withdrawal Scale \[COWS\] score ≤5 on the Naloxone Challenge) but has experience in the use of opioids for non-therapeutic purposes (ie, for psychoactive effects) on at least 10 occasions within the last year and at least once in the 12 weeks prior to the screening visit. 7. Subject demonstrates adequate VRH at screening during VRH assessment, defined as a minimum increase in ETCO2 of 10 mmHg and an increase in minute ventilation appropriate per investigator's discretion. 8. Ability and willingness to abstain from alcohol-, caffeine-, and xanthine-containing beverages or food (eg, coffee, tea, cola, chocolate, energy drinks) as well as poppy seeds from 48 hours (2 days) prior to each admission to the clinical facility until study discharge (including clinic furloughs). 9. Female subjects who are non-pregnant, non-lactating, and either postmenopausal for at least 1 year or surgically sterile for at least 3 months, or, if of childbearing potential, will agree to use adequate contraception from 28 days and/or their last confirmed menstrual period prior to study enrollment (whichever is longer) until 90 days after the follow-up visit. Male subjects, if not surgically sterilized, must agree to use adequate contraception and not donate sperm from first admission to the clinical research center until 90 days after the follow-up visit. Adequate contraception (for both males and females) is defined as using spermicide with a single barrier method: diaphragm, cervical cap, or condom. For female participants and female partners of male participan…