Identification of Optimal Measures of Human Abuse Potential: A Post Hoc Assessment of 19 Studies.

BACKGROUND: Human abuse potential studies include multiple measures to assess the subjective effects of central nervous system-active drugs. In this retrospective analysis, measurement properties of commonly used measures were assessed, and factor analysis was conducted to identify a core battery of measures. METHODS: Measures of positive, negative and other effects, for example, bipolar "at-the-moment" Drug Liking visual analog scale (VAS), were derived for active controls and placebo from 19 studies in recreational drug users (N = 570). Distribution, placebo response, variability, convergent/discriminant validity, parameter effect sizes (eg, maximum effect [Emax], time-averaged area under the effect curve), and predictive validity were evaluated. A factor analysis was conducted with 9 studies. RESULTS: Most parameters were not normally distributed. Bipolar VAS exhibited the lowest variability. Drug Liking VAS Emax was very sensitive, showed large effect sizes (>1.0), and was moderately to strongly correlated with Emax of other positive effects measures (r > 0.5), but weaker with less specific scales (eg, high, Any Effects VAS); time-averaged area under the effect curve showed higher variability and lower effect sizes. Maximum effect at any dose (EmaxD) was significantly correlated with Emax across all selected measures and showed higher effect sizes. In the overall factor analysis, factors could be categorized into positive effects/euphoria (77% of variance), negative effects (17.9%), and pharmacologic effects (5%). For predictive validity, effect sizes for Drug Liking VAS Emax/EmaxD were moderately correlated with postmarket adverse events related to abuse (R = 0.52). CONCLUSIONS: A core battery of 7 subjective measures was proposed, with additional measures added based on pharmacologic effects.

Interaction of Ethanol and Oral ANS-6637, a Selective ALDH2 Inhibitor in Males: A Randomized, Double-Blind, Placebo-Controlled, Single-Ascending Dose Cohort Study.

BACKGROUND: ANS-6637, an orally bioavailable selective and reversible aldehyde dehydrogenase-2 (ALDH2) inhibitor, is under development for drug and alcohol use disorders. During the elimination of alcohol, ALDH2 metabolizes acetaldehyde to acetate; inhibiting this enzyme can lead to aversive reactions due to the accumulation of acetaldehyde. Thus, understanding the safety and tolerability of ANS-6637 in combination with alcohol is essential. TRIAL DESIGN AND METHODS: Forty eight healthy males participated in a randomized, double-blind, placebo-controlled, single-ascending dose cohort study of oral ANS-6637. Eligible participants were randomized to ANS-6637 (n = 36) or placebo (n = 12) in a 3:1 fashion in each of 6 dose cohorts (8 per cohort; ANS-6637 dose levels were 25, 50, 100, 200, 400, and 600 mg). Two hours after receiving study drug, participants drank up to 5 standard drinks, 1 every 30 minutes. Safety assessments, pharmacodynamic measures, and pharmacokinetic blood samples were obtained. RESULTS: Flushing was the most common adverse event (AE) associated with ANS-6637 (24 of 36 participants) compared with placebo (3 of 12). Statistically significant, but modest, increases in heart rate (HR) occurred (+10.5 bpm after 2 drinks; +16.9 to + 20.5 bpm after 3rd through 5th drink). No participant met HR or systolic blood pressure criteria for stopping ethanol administration. There were no clinically significant QTc interval prolongations. Individuals receiving ANS-6637 reported lower ratings of liking, alcohol effects, and feeling drunk. CONCLUSIONS: A single oral dose of ANS-6637 with up to 5 standards drinks over 2.5 hours was generally well tolerated in healthy males. The most common pharmacological response was flushing and an increase in HR, which are known effects of acetaldehyde accumulation and consistent with inhibition of ALDH2 with oral ANS-6637 in combination with alcohol. The results of this alcohol interaction study support further testing of ANS-6637 in individuals who consume alcohol heavily.

Abuse potential of mirogabalin in recreational polydrug users.

Mirogabalin is a selective calcium channel α2δ subunit ligand being developed to treat neuropathic pain. In accordance with US Food and Drug Administration (FDA) guidance, the human abuse potential of mirogabalin (15-105 mg) was examined, relative to placebo, diazepam (15 or 30 mg), and pregabalin (200 or 450 mg), in two single-dose, randomized, double-blind, placebo- and active-controlled crossover studies in recreational polydrug users who could discern between positive comparator and placebo. The primary endpoint was maximum observed effect (E max) for Drug Liking Visual Analog Scale. At therapeutic doses, mirogabalin Drug Liking E max did not differ significantly from placebo and was significantly lower than diazepam and pregabalin. This indicates therapeutic doses mirogabalin may have less abuse potential versus diazepam or pregabalin. At supratherapeutic doses (⩾4× therapeutic dose), mirogabalin had significantly higher Drug Liking E max than placebo, but lower E max than pregabalin. In both studies, therapeutic doses of mirogabalin demonstrated limited evidence of abuse potential.

Pharmacokinetic and Pharmacodynamic Correlations From 2 Studies Evaluating Abuse Potential of Hydrocodone Extended-Release Tablets.

Pharmacokinetic (PK)/pharmacodynamic (PD) correlations were explored in 2 human abuse potential studies of orally and intranasally administered hydrocodone extended-release (ER) 45 mg in healthy, nondependent opioid users. In a crossover study design, subjects received intact hydrocodone ER, finely milled hydrocodone ER, and hydrocodone powder in solution in the oral study and finely milled hydrocodone ER, hydrocodone powder, and finely milled Zohydro® ER in the intranasal study. Spearman ρ2 and Pearson r2 values were calculated for PD (maximum effect [Emax ] for "at the moment" Drug Liking, Overall Drug Liking, and Take Drug Again visual analog scales [VAS]) vs PK (partial area under the concentration-time curve [AUC], maximum drug concentration [Cmax ], time to Cmax [Tmax ], and abuse quotient [PK AQ; Cmax /Tmax ]) for all treatments. In the oral study, correlations were strongest between Emax of "at the moment" Drug Liking and PK parameters (Cmax [ρ2  = 0.4446], PK AQ [ρ2  = 0.5179], Tmax [ρ2  = 0.5093], and early systemic exposure [ρ2  = 0.4782]). For Overall Drug Liking and Take Drug Again VAS, ρ2 values for correlations with PK parameters ranged from 0.2620 to 0.3637. In the intranasal study, no clear correlations between PK and PD parameters were apparent.

Abuse potential assessment of cannabidiol (CBD) in recreational polydrug users: A randomized, double-blind, controlled trial.

RATIONALE: Treatment with a highly purified oral solution of cannabidiol (CBD), derived from the plant Cannabis sativa L., demonstrated some evidence of central nervous system (CNS)-related adverse events in patients enrolled in phase 3 trials for treatment of childhood-onset epilepsy. Cannabidiol was categorized as a Schedule 1 substance by the United States Drug Enforcement Administration; therefore, it was important to test CBD for human abuse potential. METHODS: This was a single-dose, randomized, double-blind, double-dummy, placebo- and active-controlled crossover trial. The abuse potential of single oral doses of plant-derived pharmaceutical formulations of highly purified CBD (Epidiolex®; 750 mg, 1500 mg, and 4500 mg) was compared with that of single oral doses of alprazolam (2 mg), dronabinol (10 mg and 30 mg), and placebo in healthy recreational polydrug users. The primary endpoint to assess abuse potential was the maximum effect (Emax) on Drug-Liking visual analog scale (VAS). Other measurements included Emax on Overall Drug-Liking VAS, Take Drug Again VAS, positive and negative effects, other subjective effects, and Drug Similarity VAS. Cognitive and psychomotor functions were assessed using the Divided Attention Test, the Hopkins Verbal Learning Test-Revised, and the Digit-Symbol Substitution Task. Pharmacokinetic parameters were determined for CBD and its major metabolites. Standard safety measures and adverse events were assessed. PRINCIPAL RESULTS: Of 95 eligible subjects, 43 qualified for the treatment phase, received at least 1 dose of investigational medicinal product, and were included in safety assessments; 35 subjects were included in the pharmacodynamic analysis. Subjects receiving alprazolam and dronabinol had significantly higher Drug-Liking Emax (P < 0.0001) compared with those receiving placebo, confirming study validity. Compared with placebo, Drug-Liking was not significantly different for subjects taking 750-mg CBD (P = 0.51). Drug-Liking Emax values for 1500-mg and 4500-mg CBD were significantly different from placebo (P = 0.04 and 0.002, respectively); however, the mean differences were <10 points on VAS compared with >18-point differences between positive controls and placebo. Alprazolam and dronabinol had significantly higher Drug-Liking, Overall-Liking, and Take Drug Again VAS Emax values compared with all doses of CBD (P ≤ 0.004). In contrast to alprazolam, CBD administration had no observable effect on cognitive/psychomotor tests. Pharmacokinetic parameters for CBD in this trial were consistent with previous studies. The majority of adverse events reported during the trial were of mild or moderate severity; no serious adverse events or deaths were reported. CONCLUSION: Administration of a therapeutic dose of CBD (750 mg) showed significantly low abuse potential in a highly sensitive population of polydrug users. Although high and supratherapeutic doses of CBD (1500 mg and 4500 mg, respectively) had detectable subjective effects compared with placebo; the effects were significantly lower than those observed with alprazolam and dronabinol.

Effect of Buprenorphine Weekly Depot (CAM2038) and Hydromorphone Blockade in Individuals With Opioid Use Disorder: A Randomized Clinical Trial.

Importance: Buprenorphine is an efficacious, widely used treatment for opioid use disorder (OUD). Daily oral transmucosal formulations can be associated with misuse, diversion, and nonadherence; these limitations may be obviated by a sustained release formulation. Objective: To evaluate the ability of a novel, weekly, subcutaneous buprenorphine depot formulation, CAM2038, to block euphorigenic opioid effects and suppress opioid withdrawal in non-treatment-seeking individuals with OUD. Design, Setting, and Participants: This multisite, double-blind, randomized within-patient study was conducted at 3 controlled inpatient research facilities. It involved 47 adults with DSM-V moderate-to-severe OUD. The study was conducted from October 12, 2015 (first patient enrolled), to April 21, 2016 (last patient visit). Interventions: A total of five 3-day test sessions evaluated the response to hydromorphone (0, 6, and 18 mg intramuscular in random order; 1 dose/session/day). After the first 3-day session (ie, qualification phase), participants were randomized to either CAM2038 weekly at 24 mg (n = 22) or 32 mg (n = 25); the assigned CAM2038 dose was given twice, 1 week apart (day 0 and 7). Four sets of sessions were conducted after randomization (days 1-3, 4-6, 8-10, and 11-13). Main Outcomes and Measures: The primary end point was maximum rating on the visual analog scale for drug liking. Secondary end points included other visual analog scale (eg, high and desire to use), opioid withdrawal scales, and physiological and pharmacokinetic outcomes. Results: A total of 46 of 47 randomized participants (mean [SD] age, 35.5 [9] years; 76% male [n = 35]) completed the study. Both weekly CAM2038 doses produced immediate and sustained blockade of hydromorphone effects (liking maximum effect, CAM2038, 24 mg: effect size, 0.813; P < .001, and CAM2038, 32 mg: effect size, 0.753; P < .001) and suppression of withdrawal (Clinical Opiate Withdrawal Scale, CAM2038, 24 mg: effect size, 0.617; P < .001, and CAM2038, 32 mg: effect size, 0.751; P < .001). CAM2038 produces a rapid initial rise of buprenorphine in plasma with maximum concentration around 24 hours, with an apparent half-life of 4 to 5 days and approximately 50% accumulation of trough concentration from first to second dose (trough concentration = 0.822 and 1.23 ng/mL for weeks 1 and 2, respectively, with 24 mg; trough concentration = 0.993 and 1.47 ng/mL for weeks 1 and 2, respectively, with 32 mg). Conclusions and Relevance: CAM2038 weekly, 24 and 32 mg, was safely tolerated and produced immediate and sustained opioid blockade and withdrawal suppression. The results support the use of this depot formulation for treatment initiation and stabilization of patients with OUD, with the further benefit of obviating the risk for misuse and diversion of daily buprenorphine while retaining its therapeutic benefits. Trial Registration: Clinicaltrials.gov Identifier: NCT02611752.

Evaluating the abuse potential of opioids and abuse-deterrent -opioid formulations: A review of clinical study methodology.

With the development of opioid abuse-deterrent formulations (ADFs), there is a need to conduct well-designed human abuse potential studies to evaluate the effectiveness of their deterrent properties. Although these types of studies have been conducted for many years, largely to evaluate inherent abuse potential of a molecule and inform drug scheduling, methodological approaches have varied across studies. The focus of this review is to describe current "best practices" and methodological adaptations required to assess abuse-deterrent opioid formulations for regulatory submissions. A literature search was conducted in PubMed® to review methodological approaches (study conduct and analysis) used in opioid human abuse potential studies. Search terms included a combination of "opioid," "opiate," "abuse potential," "abuse liability," "liking," AND "pharmacodynamic," and only studies that evaluated single doses of opioids in healthy, nondependent individuals with or without prior opioid experience were included. Seventy-one human abuse potential studies meeting the prespecified criteria were identified, of which 21 studies evaluated a purported opioid ADF. Based on these studies, key methodological considerations were reviewed and summarized according to participant demographics, study prequalification, comparator and dose selection, route of administration and drug manipulation, study blinding, outcome measures and training, safety, and statistical analyses. The authors recommend careful consideration of key elements (eg, a standardized definition of a "nondependent recreational user"), as applicable, and offer key principles and "best practices" when conducting human abuse potential studies for opioid ADFs. Careful selection of appropriate study conditions is dependent on the type of ADF technology being evaluated.

Oral Abuse Potential, Pharmacokinetics, and Safety of Once-Daily, Single-Entity, Extended-Release Hydrocodone (HYD) in Recreational Opioid Users.

OBJECTIVES: A once-daily, extended-release hydrocodone bitartrate tablet with abuse-deterrent properties (Hysingla ER [HYD]) is available for the treatment of chronic pain in appropriate patients. This study evaluated the oral abuse potential and pharmacokinetics (PK) of HYD intact, chewed, or milled to fine particles in comparison with hydrocodone solution or placebo. DESIGN: Single-center, double-blind, randomized, five-period, five-treatment crossover study. SUBJECTS: Healthy adult, nondependent, recreational opioid users. METHODS: Forty subjects received orally administered treatments of hydrocodone 60 mg solution, HYD 60 mg intact, HYD 60 mg chewed, HYD 60 mg milled to fine particles, or placebo, separated by a five- to seven-day washout. Assessments over 36 hours postdose included subjective measures of drug liking and willingness to take drug again (assessed using visual analog scales [VAS]), pupillometry, PK, and safety measures. RESULTS: Following oral administration, HYD intact, HYD chewed, and HYD fine particles led to significantly lower "at this moment" drug liking compared with hydrocodone solution. HYD intact and chewed were significantly different from hydrocodone solution on overall drug liking, take drug again, and good effects. Pupil constriction, as measured by pupillometry, occurred later with HYD intact and HYD chewed than with hydrocodone solution. Across treatments (hydrocodone solution, HYD fine particles, HYD chewed, and HYD intact, respectively), mean C max and rate of absorption (C max /T max ) values decreased, respectively, and median T max values increased, respectively. Safety was consistent with the known effects of opioid agonists. CONCLUSION: HYD demonstrated reduced oral abuse potential compared with hydrocodone solution in healthy adult, nondependent, recreational opioid users.

Oral Human Abuse Potential of Oxycodone DETERx® (Xtampza® ER).

Oxycodone DETERx® (Collegium Pharmaceutical Inc, Canton, Massachusetts) is an extended-release, microsphere-in-capsule, abuse-deterrent formulation designed to retain its extended-release properties after tampering (eg, chewing/crushing). This randomized, double-blind, placebo-controlled, triple-dummy study evaluated the oral abuse potential of intact and chewed oxycodone DETERx capsules compared with crushed immediate-release oxycodone. Subjects with a history of recreational opioid use who were nondependent/nontolerant to opioids were enrolled. Treatments included intact oxycodone DETERx (high-fat, high-calorie meal and fasted), chewed oxycodone DETERx (high-fat, high-calorie meal and fasted), crushed immediate-release oxycodone (fasted), and placebo (high-fat, high-calorie meal). Plasma samples were collected to determine pharmacokinetic parameters. The primary endpoint was drug liking at the moment; other endpoints included drug effects questionnaire scores, Addiction Research Center Inventory/Morphine Benzedrine Group score, pupillometry measurements, and safety. Thirty-eight subjects completed the study. Chewed and intact oxycodone DETERx were bioequivalent, unlike crushed immediate-release oxycodone, which yielded higher peak oxycodone plasma concentrations compared with all methods of oxycodone DETERx administration. The mean maximum (peak) effect (Emax ) for drug liking was significantly lower for chewed and intact oxycodone DETERx than for crushed immediate-release oxycodone (P < .01). The time to Emax was significantly longer for chewed and intact oxycodone DETERx than for crushed immediate-release oxycodone (P < .0001). Scores for feeling high and Addiction Research Center Inventory/Morphine Benzedrine Group scores demonstrated lower abuse potential for chewed and intact oxycodone DETERx compared with crushed immediate-release oxycodone. Study treatments were well tolerated; no subjects experienced serious adverse events. These results demonstrate the lower oral abuse potential of chewed and intact oxycodone DETERx than crushed immediate-release oxycodone.

Abuse Potential Study of ALO-02 (Extended-Release Oxycodone Surrounding Sequestered Naltrexone) Compared with Immediate-Release Oxycodone Administered Orally to Nondependent Recreational Opioid Users.

Objective: To evaluate the abuse potential of ALO-02, an abuse-deterrent formulation comprising pellets of extended-release oxycodone hydrochloride surrounding sequestered naltrexone hydrochloride. Design: Randomized, double-blind, placebo-/active-controlled, 6-way crossover study, with naloxone challenge, drug discrimination, and treatment phases. Subjects: Nondependent, recreational opioid users. Methods: Oral administration of crushed and intact ALO-02, crushed immediate-release (IR) oxycodone, and placebo. Primary endpoints were Drug Liking and High measured on visual analog scales and reported as maximum effect (E max ) and area-under-the-effect-curve from 0 to 2 hours (AUE 0-2h ). Other pharmacodynamic, pharmacokinetic and safety assessments were included. Results: Drug Liking and High (E max ) for crushed oxycodone IR 40 mg were significantly higher compared with placebo, confirming study validity ( P < 0.0001). Drug Liking and High (E max, AUE 0-2h ) for crushed ALO-02 (40 mg/4.8 mg and 60 mg/7.2 mg) were significantly lower compared to corresponding doses of crushed oxycodone IR (40 and 60 mg; P < 0.0001). Likewise, Drug Liking and High (E max and AUE 0-2h ) for intact ALO-02 60 mg/7.2 mg were significantly lower compared with crushed oxycodone IR 60 mg ( P < 0.0001). Secondary pharmacodynamic endpoints and plasma concentrations of oxycodone and naltrexone were consistent with these results. Fewer participants experienced adverse events (AEs) after ALO-02 (crushed or intact: 71.1-91.9%) compared with crushed oxycodone IR (100%). Most common AEs following crushed ALO-02 and oxycodone IR were euphoric mood, pruritus, somnolence, and dizziness. Conclusions: The results suggest that ALO-02 (crushed or intact) has lower abuse potential than crushed oxycodone IR when administered orally in nondependent, recreational opioid users.

Abuse deterrence testing: A dose ratio escalation study examining naloxone coadministered with intravenous hydromorphone in non-treatment-seeking, opioid-dependent drug users.

OBJECTIVE: To assess the reduction in intravenous (IV) abuse potential of hydromorphone from different dose ratio combinations with naloxone in opioid-dependent drug users. DESIGN: Randomized, blinded, dose ratio escalation study. SETTING: Single center. PARTICIPANTS: Following conversion to a stable IV dose of hydromorphone, 12 non-treatment-seeking, opioid-dependent subjects were randomly assigned and received at least one dose of study drug; seven subjects received all five study treatments. Five subjects withdrew early from the treatment phase: adverse events (2) and participant decision (3). INTERVENTIONS: Participants underwent a dose-selection phase to stabilize on an individualized hydromorphone dose. Stable subjects were dosed intravenously on 5 consecutive days. The dose received was one of five hydromorphone/naloxone dose ratios that included the combination of hydromorphone and placebo naloxone. Hydromorphone/naloxone treatment always involved increasing dose ratios of naloxone (8:1, 6:1, 4:1, and 2:1) with the hydromorphone-placebo naloxone treatment randomly assigned within the sequence of dose ratios. MAIN OUTCOME MEASURES: Drug Liking visual analog scale (VAS), Objective Opioid Withdrawal Scale (OOWS) and Subjective Opioid Withdrawal Scale (SOWS). RESULTS: Hydromorphone/naloxone placebo produced subjective effects typical of opioid administration, while hydromorphone/naloxone dose ratios were associated with significant increases in SOWS and OOWS scores (p < 0.05). Compared with hydromoprophone/naloxone placebo, naloxone reduced the effects of hydromorphone on most measures, including Drug Liking VAS, the antagonism was greatest for the 4:1 and 2:1 ratios. CONCLUSIONS: This study was an ethical investigation of the abuse deterrence potential of four hydromorphone/naloxone dose ratios. The IV coadministration of commercially available IV solutions of hydromorphone and naloxone in 4:1 and 2:1 ratios had statistically greater reductions of abuse-related opioid effects and triggers of withdrawal symptoms and there was a convergence of subjective and objective pharmacodynamic results and safety findings. An oral modified-release product, developed with a 2:1 hydromorphone/naloxone ratio, may have important public health benefits by reducing high-risk, IV abuse of prescription opioids, while providing pain relief when ingested orally and used in accordance with the Product Monograph.

Abuse liability assessment of eslicarbazepine acetate in healthy male and female recreational sedative users: A Phase I randomized controlled trial.

RATIONALE: Eslicarbazepine acetate (ESL) is a once-daily oral antiepileptic drug for the treatment of partial-onset seizures. Adverse events such as dizziness and somnolence reported in clinical studies suggest that ESL has detectable central nervous system (CNS) effects in addition to its antiepileptic effects. This Phase I study evaluated the abuse liability of ESL compared with that of alprazolam (ALP) and placebo (PBO) in recreational CNS depressant users. METHODS: In this single-dose, randomized, double-blind, PBO- and active-controlled crossover study, healthy recreational CNS depressant users who could discern between ALP 2mg and PBO received single oral doses of each of the following treatments with a washout interval of ≥7days between each treatment: ESL (800mg, 1600mg, 2000mg, and 2400mg); ALP (1.5mg and 3.0mg); and PBO. Subjective measures, including visual analog scales (VASs) e.g., Drug-Liking (primary endpoint), and Addiction Research Center Inventory (ARCI) Morphine-Benzedrine Group (MBG), Pentobarbital Chlorpromazine Alcohol Group (PCAG), and Lysergic Acid Diethylamide Group scales were evaluated at multiple time points up to 24h postdose. Cognitive effects were evaluated using the Choice Reaction Time (CRT), Divided Attention (DAT) and Hopkins Verbal Learning Task-Revised tests. PRINCIPAL RESULTS: Peak scores for Drug-Liking VAS (maximum effect [Emax]) were significantly higher for both ALP doses than for PBO (p<0.0001), thereby confirming study validity. Drug-Liking VAS Emax was significantly lower for all ESL doses than both ALP doses (p<0.0001). Drug-Liking VAS Emax for ESL 800mg was similar to that for PBO (least squares [LS] mean difference: 3.6; p=0.19). At the three higher ESL doses (1600mg and the supratherapeutic doses of 2000mg and 2400mg), Drug-Liking VAS Emax was significantly higher than for PBO, although the differences were minimal (LS mean difference: 9.3-13.3 out of 100). For most secondary subjective endpoints (i.e., Good Effects VAS and High VAS, ARCI-MBG, Take Drug Again VAS, Overall Drug-Liking VAS, and ARCI-PCAG; p<0.05), the effect of ESL (all doses) was significantly less than that of ALP (both doses). On most secondary measures, the dose-response relationship was relatively flat or showed saturation at higher ESL doses. Although significant differences were observed for ESL compared with those for PBO for some specific CRT and DAT endpoints (i.e., reaction time, manual tracking, hit latency), ALP demonstrated significant and dose-dependent impairment on the majority of cognitive endpoints when compared with PBO and ESL. Mean plasma concentrations of the active metabolite of ESL, eslicarbazepine, increased with increasing ESL dose. Pharmacokinetic parameters estimated for eslicarbazepine were generally comparable with results from previous studies in healthy volunteers. CONCLUSION: This study demonstrated that single doses of ESL may have less abuse liability than ALP in recreational sedative users. Although ESL had detectable subjective effects and showed some drug-'liking' at higher doses, the magnitude of these effects was small.

Assessment of the Abuse Potential of the Orexin Receptor Antagonist, Suvorexant, Compared With Zolpidem in a Randomized Crossover Study.

Suvorexant is a dual orexin receptor antagonist approved in the United States and Japan for the treatment of insomnia at a maximum dose of 20 mg. This randomized double-blind crossover study evaluated the abuse potential of suvorexant in 36 healthy recreational polydrug users with a history of sedative and psychedelic drug use. Single doses of suvorexant (40, 80, and 150 mg: 2-7.5 × maximum dose), zolpidem (15 and 30 mg: 1.5-3 × maximum dose), and placebo were administered, with a 10-day washout between treatments. Subjective and objective measures, including visual analog scales (VASs), Addiction Research Center Inventory, and cognitive/psychomotor tests, were evaluated for 24-hour postdose. Suvorexant had significantly greater peak effects on "drug liking" VAS (primary endpoint) than placebo. Although effects of suvorexant on abuse potential measures were generally similar to zolpidem, they remained constant across doses, whereas zolpidem often had greater effects at higher doses. Suvorexant (all doses) had significantly fewer effects than zolpidem 30 mg on secondary measures, such as "high" VAS, Bowdle VAS, and Addiction Research Center Inventory morphine-benzedrine group. The overall incidence of abuse-related adverse events, such as euphoric mood and hallucination, was numerically lower with suvorexant than zolpidem. In agreement with its classification as a schedule IV drug, suvorexant demonstrated abuse potential, compared with placebo. The abuse potential was similar to zolpidem using certain measures, but with a reduced incidence of abuse-related adverse events. Although this suggests that the overall abuse liability of suvorexant may be lower than zolpidem, the actual abuse rates will be assessed with the postmarketing experience.

Intranasal Abuse Potential, Pharmacokinetics, and Safety of Once-Daily, Single-Entity, Extended-Release Hydrocodone (HYD) in Recreational Opioid Users.

OBJECTIVES: A once-daily, extended-release hydrocodone bitartrate tablet with abuse-deterrent properties (Hysingla ER® [HYD]) is available for the treatment of chronic pain in appropriate patients. This study evaluated the intranasal abuse potential and pharmacokinetics of HYD coarse and fine particles vs hydrocodone powder or placebo. DESIGN: Single-center, double-blind, positive- and placebo-controlled, randomized, four-treatment crossover study. SUBJECTS: Healthy adult, nondependent, recreational opioid users with a history of intranasal abuse. METHODS: During four treatment periods, subjects (N = 31) received hydrocodone powder 60 mg, HYD coarse particles 60 mg, HYD fine particles 60 mg, or placebo, with five-to-seven-day washouts between treatments. Measures over 36 hours postdose included drug-liking and willingness to take drug again, assessed using visual analog scales (VASs), pupillometry, intranasal irritation, and pharmacokinetics. RESULTS: Insufflation of both HYD coarse and fine particles led to lower "At this Moment" Drug Liking VAS peak values compared with hydrocodone powder, but higher values compared with placebo (P < 0.001 for all comparisons). Similar results were observed for Overall Drug Liking VAS, Take Drug Again VAS, and Subjective Drug Value. Compared with hydrocodone, insufflation of HYD particles led to reduced miosis and increased nasal irritation. Mean hydrocodone Cmax following insufflation of HYD coarse particles, HYD fine particles, and hydrocodone powder was 27.5, 36.5, and 105.8 ng/mL, respectively; median Tmax was ≥2-fold longer with either HYD particle size than hydrocodone powder; and (Cmax/Tmax) was 9.5, 13.4, and 82.0 ng/mL/h, respectively. Safety was consistent with that of opioid agonists. CONCLUSIONS: HYD demonstrated reduced intranasal abuse potential compared with hydrocodone powder.

Comparing the Effect of Tampering on the Oral Pharmacokinetic Profiles of Two Extended-Release Oxycodone Formulations with Abuse-Deterrent Properties.

OBJECTIVE: Oxycodone DETERx® is an extended-release (ER), microsphere-in-capsule abuse-deterrent-formulation designed to retain its extended-release properties following tampering or misuse (e.g., chewing, crushing). This study assessed the safety and pharmacokinetics of orally administered intact and crushed Oxycodone DETERx® capsules compared with intact and crushed reformulated OxyContin® tablets and crushed immediate-release oxycodone tablets (IR oxycodone). METHODS: This was a randomized, open-label, active-controlled, cross-over study. Healthy subjects received five oxycodone treatments (40 mg) with a standardized high-fat, high-calorie meal: Oxycodone DETERx® (intact or crushed), OxyContin® (intact or crushed), and IR oxycodone (crushed). Blood samples were collected for assessment of oxycodone plasma concentrations. RESULTS: Thirty-eight subjects completed the study. Both crushed and intact Oxycodone DETERx® resulted in lower peak plasma concentrations when compared with IR oxycodone. Crushed Oxycodone DETERx® was bioequivalent to intact Oxycodone DETERx® and exhibited a numerically lower Cmax . Also, median Tmax was unchanged by crushing. In contrast, mean peak plasma oxycodone concentrations for crushed OxyContin® were significantly higher compared with intact OxyContin® and were bioequivalent to IR oxycodone. Median Tmax for crushed OxyContin® was the same as IR oxycodone and 3.25 hours shorter than intact OxyContin®. CONCLUSIONS: These data demonstrate that when crushed and taken orally, Oxycodone DETERx® maintains its EXTENDED-release profile, while crushed OxyContin® shows a pharmacokinetic profile similar to an immediate-release product. These results suggest that Oxycodone DETERx® may be less attractive to illicit drug users compared with existing abuse-deterrent-formulations, while providing a safer option for patients who may unknowingly crush their medication such as those who have difficulty swallowing.

Intranasal administration of crushed ALO-02 (extended-release oxycodone with sequestered naltrexone): A randomized, controlled abuse-potential study in nondependent recreational opioid users.

ALO-02 is an abuse-deterrent formulation consisting of capsules filled with pellets of extended-release oxycodone surrounding sequestered naltrexone. This randomized, double-blind, placebo-/active-controlled, 4-way crossover study examined the abuse potential of crushed ALO-02 administered intranasally to healthy, nondependent, recreational opioid users. Following drug discrimination and naloxone challenge, eligible participants (n = 32) entered a 4-way crossover treatment phase: crushed single dose of 1 of 2 placebos, ALO-02 30 mg/3.6 mg (oxycodone/naltrexone) or oxycodone immediate-release (IR) 30 mg. Primary end points were Drug Liking and High, measured on visual analog scales (VAS) summarized as maximum effect (Emax ) and effect occurring over 2 hours postdose (AUE0-2 h ). Crushed ALO-02 resulted in significantly lower scores versus oxycodone IR on Drug Liking (Emax , 60.5 vs 92.8; AUE0-2 h , 105.4 vs 160.0, respectively) and High (Emax , 25.2 vs 86.9; AUE0-2 h , 27.1 vs 136.4, respectively; n = 28; P < .0001). Adverse events occurred most frequently with oxycodone IR, followed by ALO-02, then placebo, and were considered mild and consistent with opioid therapy. Crushed ALO-02 administered intranasally to nondependent recreational opioid users resulted in significantly lower scores on Drug Liking/High VAS and other positive subjective measures versus crushed oxycodone IR, suggesting less abuse potential. Demonstration of actual abuse deterrence in the real world requires further research.

Self-reports of prescription opioid abuse and diversion among recreational opioid users in a Canadian and a United States city.

OBJECTIVE: To explore behaviors related to prescription opioid abuse and diversion in individuals who self-reported past recreational (nonmedical) opioid use. DESIGN: A questionnaire was developed and included in two abuse potential clinical studies conducted in Canada (Toronto, ON, August 2010 to January, 2011) and the United States (Salt Lake City, UT, February-May 2011). PARTICIPANTS: Recreational opioid users. MAIN OUTCOME MEASURE(S): Self-reported behaviors related to prescription opioid abuse and diversion. RESULTS: The questionnaire was completed by 174 participants in the Canadian study and 80 participants in the US study. Most participants reported that they used prescription opioids for nonmedical purposes a few times a month. Most had taken their first prescription opioid between the ages of 12 and 24 years and the two most common reasons were to treat pain or to feel high/stoned. When asked about specific opioids taken for nonmedical purposes in the past year, oxycodone, acetaminophen with codeine, and morphine were commonly used by both cohorts, whereas hydrocodone use was substantially greater in the US cohort versus the Canadian cohort. Participants reported various tampering methods and routes of administration, with swallowed whole, crushed and snorted, and chewed/crushed and swallowed as the most prevalent. Most participants indicated taking other drugs with prescription opioids to get high, most commonly marijuana and alcohol. The most common sources for obtaining prescription opioids were family/friends. CONCLUSIONS: Two cohorts of recreational opioid users from Canada and the United States reported similar experiences with various prescription opioids and indicated a predominance of diversion from family/friends.

Brain Network Activation (BNA) reveals scopolamine-induced impairment of visual working memory.

The overarching goal of this event-related potential (ERP) study was to examine the effects of scopolamine on the dynamics of brain network activation using a novel ERP network analysis method known as Brain Network Activation (BNA). BNA was used for extracting group-common stimulus-activated network patterns elicited to matching probe stimuli in the context of a delayed matching-to-sample task following placebo and scopolamine treatments administered to healthy participants. The BNA extracted networks revealed the existence of two pathophysiological mechanisms following scopolamine, disconnection, and compensation. Specifically, weaker frontal theta and parietal alpha coupling was accompanied with enhanced fronto-centro-parietal theta activation relative to placebo. In addition, using the characteristic BNA network of each treatment as well as corresponding literature-guided selective subnetworks as combined biomarkers managed to differentiate between individual responses to each of the treatments. Behavioral effects associated with scopolamine included delayed response time and impaired response accuracy. These results indicate that the BNA method is sensitive to the effects of scopolamine on working memory and that it may potentially enable diagnosis and treatment assessment of dysfunctions associated with cholinergic deficiency.

Estradiol and mental rotation: relation to dimensionality, difficulty, or angular disparity?

Several studies have reported that performance on spatial rotation tests is better at menses than at high estradiol phases of the menstrual cycle in women. These effects are debated because nearly all reports of menstrual cycle variability have relied on a single test, the Mental Rotations Test (MRT, Vandenberg and Kuse, 1978). In the present study, we investigated key features of the MRT that might be responsible for its association with estradiol levels. We hypothesized that associations could be demonstrated for other tasks that share the same characteristics. Forty-four women ages 20-38 years, matched on education and general ability, were assessed at low (n=24) or high (n=20) estradiol stages of the menstrual cycle on a set of spatial tests that varied in dimensionality, plane of rotation, angular disparity, and effortfulness. Saliva was used to quantify estradiol and progesterone. Low estradiol was found to be associated with significantly better accuracy on the MRT and also on a mental rotation task that required large angles of rotation but employed only two-dimensional object representations and rotations limited to the picture plane. In contrast, a task using identical stimuli that required only small angles of rotation did not show an estradiol effect. A group difference also was seen on a test of perceptual closure. The results confirm that the estradiol effect is not limited to the MRT, and identify the rotational element, but also aspects of figural perception, as possible processes that may be responsive to estrogens. These findings advance our understanding by showing an association between estradiol and discrete spatial processes. Implications for understanding the origins of the robust sex difference commonly observed on the MRT are discussed.

Assessing the subjective and physiological effects of intranasally administered crushed extended-release morphine formulations with and without a sequestered naltrexone core in recreational opioid users.

OBJECTIVE: To evaluate the pharmacodynamic (PD) effects of morphine sulfate and naltrexone hydrochloride extended-release (MSN) capsules compared with controlled-release morphine sulfate (MS) and placebo when crushed and administered intranasally. METHODS: The present study was a randomized, double-blinded, placebo-controlled, single-dose (30 mg), three-way crossover study in healthy, nondependent recreational opioid users. PD measures included assessment of subjective drug effects using visual analogue scales (VAS) ranging from 0 to 100 and assessments of pupil diameter. Blood samples were collected for pharmacokinetic analyses. RESULTS: Both MS and MSN showed significantly higher PD values compared with placebo. MSN showed significantly lower scores for drug liking and high VAS scores on both mean peak effect (Emax) (69.6 and 55.2, respectively) and in area under the effect curve over 2 h (86.3 and 66.7, respectively) following dosing compared with MS (Emax 87.6 and 86.6, respectively; area under the curve over 2 h 120.6 and 132.9, respectively; P<0.001). MSN showed significantly lower Emax for all other positive subjective effects (good drug effects, overall drug liking, and take drug again VAS scores) compared with MS (P<0.001). Peak minimum pupil diameter was significantly larger for MSN than MS (P=0.002). Mean peak plasma concentration (Cmax) and median time to Cmax for morphine following administration of MSN and MS were similar (27.3 ng/mL and 0.57 h versus 27.7 ng/mL and 0.6 h, respectively). Naltrexone mean Cmax was 1497 pg/mL after MSN and median time to Cmax was 0.55 h. CONCLUSIONS: When crushed and administered intranasally, MSN was associated with significantly lower ratings of drug liking and other positive subjective effects compared with MS.