Study Evaluating the Abuse Potential of NEURONTIN® in Healthy Non-drug Dependent, Recreational Opioid Users

This will be a randomized, double-blind, double-dummy, placebo- and active-controlled, 6 treatment, 6-period crossover single-dose, Williams square design study in healthy male and/or female adult, non-drug-dependent recreational opioid users.

The study includes Screening, a Qualification Phase consisting of a Naloxone Challenge and Drug Discrimination crossover study, a Treatment Phase and Follow-up. Following successful completion of the Qualification Phase the participants will be enrolled in the Treatment phase. The Treatment Phase is a randomized, double-blind, double dummy, placebo- and active controlled, 6 treatment, 10-sequence, 6 period crossover, single-dose, Williams square design study in healthy male and/or female adult, non drug-dependent recreational users. On Day 1 of each of the Treatment Phase 6 periods, which will be separated by a washout of at least 14 days, participants will receive an oral dose of either gabapentin 600 mg or 1200 mg alone, or concomitantly with a 20 mg dose of oxycodone HCl or 20 mg monotherapy of oxycodone HCl or a placebo. Study treatments will be administered under fasted conditions (overnight fast and no food until 4 hours after dosing). Water will be allowed without restriction until 1 hour prior to dosing and 1 hour after dosing.

Eligibility Criteria:
Inclusion Criteria:

1. Male and female participants must be 18 to 55 years of age, inclusive, at the time of screening. Participants must meet reproductive criteria as outlined in the protocol.
2. Male and female participants who are overtly healthy. Healthy is defined as no clinically relevant abnormalities identified by a detailed medical history, complete physical examination, vital signs, 12-lead ECG, and/or clinical laboratory tests.
3. Participants must have drug abuse experience with opioids; ie, must have used opioids for non-therapeutic purposes (ie, for psychoactive effects) on at least 10 occasions within the last year and at least once in the 8 weeks before the Screening Visit (Visit 1).
4. Participants must satisfactorily complete both the Naloxone Challenge and the Drug Discrimination.
5. Participants who are willing and able to comply with all scheduled visits, treatment plan, laboratory tests, lifestyle considerations, and other study procedures.
6. Body mass index (BMI) of 17.5 to 34 kg/m2, inclusive; and a total body weight ≥50 kg (110 lb).
7. Capable of giving signed informed consent as described in the protocol, which includes compliance with the requirements and restrictions listed in the informed consent document (ICD) and in this protocol.

Exclusion Criteria:

1. Current or past diagnosis of any type of drug dependence within the past year. Diagnosis of substance and/or alcohol dependence (excluding caffeine and nicotine) will be assessed by the Investigator using the Diagnostic and Statistical Manual of Mental Disorders-IV (DSM-IV) criteria performed at Screening. Current drug use will be allowed if the candidate can produce a negative urine sample and are free of any signs/symptoms of withdrawal. The candidate will be informed if they have a positive breathalyzer test.
2. Evidence or history of clinically significant hematological, renal, endocrine, pulmonary, gastrointestinal, cardiovascular, hepatic, psychiatric, neurological, or allergic disease (including drug allergies, but excluding untreated, asymptomatic, seasonal allergies at the time of dosing).
3. Any condition possibly affecting drug absorption (eg, gastrectomy) excluding cholecystectomy within 1 year prior to study.
4. Abnormal baseline EtCO2 \<35mm Hg or \>45 mm Hg.
5. Clinical or laboratory evidence of active hepatitis A infection or a history of human immunodeficiency virus (HIV) infection, hepatitis B, or hepatitis C, and/or positive testing for HIV, hepatitis B surface antigen (HBsAg), hepatitis B core antibody (HBcAb), or hepatitis C antibody (HCVAb).
6. Participants with active suicidal ideation or suicidal behavior within 5 years prior to Screening as determined through the use of the Columbia Suicide Severity Rating Scale (C-SSRS) or active ideation identified at Screening or on Day 0.
7. Participants with any history of sleep apnea, myasthenia gravis or glaucoma.
8. Other acute or chronic medical or psychiatric condition including recent (within the past year) or active suicidal ideation or behavior or laboratory abnormality that may increase the risk associated with study participation or investigational product administration or may interfere with the interpretation of study results and, in the judgment of the investigator, would make the participant inappropriate for entry into this study.
9. Use of prescription or nonprescription drugs and dietary supplements within 7 days or 5 half lives (whichever is longer) prior to the first dose of investigational product. (Refer to Section 6.5 for additional details).
10. Herbal supplements, herbal medications and hormone replacement therapy must be discontinued at least 28 days prior to the first dose of study medication.
11. Previous administration with an investigational drug within 30 days (or as determined by the local requirement) or 5 half lives (whichever is longer) preceding the first dose of investigational product used in this study.
12. Positive urine drug screen (UDS) for substances of abuse at each admission in Qualification and Treatment Phase, excluding tetrahydrocannabinol (THC). If a participant presents with a positive UDS excluding THC at any admission or any visit, the investigator, at his/her discretion, may reschedule a repeat of UDS until the UDS is negative, excluding THC, before the participate is permitted to participate in any phase of the study.
13. Unable to abstain from using THC during the Qualification and Treatment Phase of the study.
14. Has participated in, is currently participating in, or is seeking treatment for substance and/or alcohol related disorders (excluding nicotine and caffeine).
15. Has a positive alcohol breathalyzer or urine test at each admission to the study center during Qualification and Treatment Phases. Positive results may be repeated and/or participants re scheduled at the Investigator's discretions.
16. Participants are heavy smokers or users of other types of nicotine products (\>20 cigarettes equivalents per day).
17. Participants are unable to abstain from smoking for at least 2 hours before and at least 8 hours after study drug administration.
18. Screening sitting blood pressure (BP) \>=140 mm Hg (systolic) or \>=90 mm Hg (diastolic), following at least 5 minutes rest. If BP is \>=140 mm Hg (systolic) or \>=90 mm Hg (diastolic), the BP should be repeated 2 more times and the average of the 3 BP values should be used to determine the participant's eligibility. Repeated BP tests should be spaced at least 5 minutes apart.
19. Baseline (screening) 12 lead electrocardiogram (ECG) that demonstrates clinically relevant abnormalities that may affect participant safety or interpretation of study results (eg, baseline corrected QT (QTc) interval as determined by the Fridericia method (QTcF) \>450 msec, complete left bundle branch block \[LBBB\], signs of an acute or indeterminate age myocardial infarction, ST T interval changes suggestive of myocardial ischemia, second or third degree atrioventricular \[AV\] block, or serious bradyarrhythmias or tachyarrhythmias). If the baseline uncorrected QT interval is \>450 msec, this interval should be rate corrected using the Fridericia method and the resulting QTcF should be used for decision making and reporting. If QTcF exceeds 450 msec, or QRS exceeds 120 msec, the ECG should be repeated 2 more times and the average of the 3 QTcF or QRS values should be used to determine the participant's eligibility. Computer interpreted ECGs should be overread by a physician experienced in reading ECGs before excluding participants.
20. Participants with ANY of the following abnormalities in clinical laboratory tests at screening, as assessed by the study specific laboratory and confirmed by a single repeat test, if deemed necessary:

    * Aspartate aminotransferase (AST) or alanine aminotransferase (ALT) level \>=1.5 × upper limit of normal (ULN);
    * Total bilirubin level \>=1.5 × ULN; participants with a history of Gilbert's syndrome may have direct bilirubin measured and would be eligible for this study provided the direct bilirubin level is \<= ULN.
21. Blood donation (excluding plasma donations) of approximately 1 pint (500 mL) or more within 60 days prior to dosing.
22. History of sensitivity to heparin or heparin induced thrombocytopenia.
23. Unwilling or unable to comply with the criteria in the Lifestyle Considerations section of this protocol.
24. History of hypersensitivity to gabapentin or oxycodone or any of the components in the formulation of the study products.
25. Investigator site staff members directly involved in the conduct of the study and their family members, site staff members otherwise supervised by the investigator, or Sponsor employees, including their family members, directly involved in the conduct of the study.