Abuse potential assessment of the new dual orexin receptor antagonist daridorexant in recreational sedative drug users as compared to suvorexant and zolpidem

Study Objectives Abuse potential properties have been reported for the dual orexin receptor antagonists (DORAs) suvorexant and lemborexant. Daridorexant is a new DORA currently in late-stage clinical development. This randomized, double-blind, double-dummy, placebo- and active-controlled 6-period crossover study assessed its abuse potential in healthy recreational sedative drug users (n=63). Methods In each study period, a single, oral, morning dose of either daridorexant (50, 100, 150 mg), placebo, or active control, i.e., suvorexant (150 mg) or zolpidem (30 mg), was administered. Primary pharmacodynamic endpoint was the Emax of the Drug-liking visual analog scale (VAS) assessed over 24 h. Several secondary subjective and objective pharmacodynamic endpoints were also assessed. Results Study validity was confirmed based on drug-liking of suvorexant and zolpidem greater than placebo applying a pre-defined 15-point validity margin (p<0.0001). Drug-liking VAS Emax (mean; 95% CI) of daridorexant at 50 mg (73.2; 69.0-77.5) was significantly lower compared to suvorexant (80.7; 77.0-84.5) and zolpidem (79.9; 76.2-83.5) (p<0.001), but similar at 100 mg (79.1; 75.0-83.3) and 150 mg (81.3; 77.7, 84.8). Such dose-related patterns were also observed for most secondary endpoints. At each daridorexant dose, Drug-liking VAS scores were greater than placebo. Both control drugs and daridorexant were safe and the pharmacokinetics of daridorexant was consistent with earlier trials indicating quick absorption and elimination. Conclusions In this large, valid human abuse potential study, daridorexant showed dose-related drug-liking among recreational sedative drug users with lower effects at the highest phase-3 dose, and similar effects at higher doses compared to supratherapeutic doses of suvorexant and zolpidem.

No Abuse Potential of Silexan in Healthy Recreational Drug Users: A Randomized Controlled Trial

Background Silexan is a lavender essential oil with established anxiolytic and calming efficacy. Here we asked whether there is a potential for abuse in human patients. Methods We carried out a phase I abuse liability single-center, double-blind, 5-way crossover study in healthy users of recreational central nervous system depressants. They received single oral doses of 80 mg (therapeutic dose) and 640 mg Silexan, 2 mg and 4 mg lorazepam (active control) and placebo in randomized order, with 4- to 14-day washout periods between treatments. Pharmacodynamic measures included validated visual analogue scales assessing positive, negative, and sedative drug effects and balance of effects; a short form of the Addiction Research Center Inventory; and a drug similarity assessment. The primary outcome measure was the individual maximum value on the drug liking visual analogue scale during 24 hours post-dose. Results Forty participants were randomized and 34 were evaluable for pharmacodynamic outcomes. In intraindividual head-to-head comparisons of the drug liking visual analogue scale maximum value, both doses of Silexan were rated similar to placebo whereas differences were observed between Silexan and lorazepam and between placebo and lorazepam (P < .001). These data were supported by all secondary measures of positive drug effects and of balance of effects. Differences between placebo and both doses of Silexan were always negligible in magnitude. Moreover, Silexan showed no sedative effects and was not perceived to be similar to commonly used drugs that participants had used in the past. Conclusions Silexan did not exhibit any abuse potential in a standard abuse potential detection screen study and is unlikely to be recreationally abused.

0500 Evaluation of the Human Abuse Potential of Single Oral Doses of V117957, a Novel, Highly Potent and Selective Partial Agonist for Nociceptin/Orphanin-FQ Peptide (NOP) Receptors

Introduction The satisfactory safety/tolerability profile of V117957, an investigational NOP receptor partial agonist, has been previously established in ~200 healthy subjects with maximum doses at 30mg following a single oral administration and 10mg once daily for 2 weeks. V117957 exhibited linear plasma exposures at doses up to 10mg. In patients with insomnia disorder, V117957 demonstrated dose-dependent improvement in sleep efficiency and sleep maintenance between 0.5mg and 10mg as measured by polysomnography and patient diaries. The current study evaluated the abuse potential and safety of V117957 in healthy, nondependent recreational polydrug users with a history of central nervous system (CNS) depressant use. Methods The abuse potential of V117957 (1mg, 6mg, 10mg), placebo, and triazolam (0.5mg, 1mg) were assessed in a randomized, double-blind, double-dummy, placebo- and positive-controlled crossover study. Triazolam was utilized as a positive control based on its comparable pharmacokinetic and pharmacodynamic characteristics. V117957 doses (1mg, 6mg, 10mg) were selected to represent therapeutic, mid-range supratherapeutic, and maximum-tolerated supratherapeutic doses, respectively. Subjects were qualified based on pharmacodynamic responses following a single oral 0.75mg triazolam dose. Drug liking was measured through 24 hours, including the primary endpoint of maximum “at the moment” Drug-Liking Visual Analog Scale, as recommended by FDA. Secondary endpoints included Divided Attention Test (DAT) and Choice Reaction Time (CRT). Results The positive control (triazolam 0.5mg, 1mg) produced statistically significant greater abuse potential and cognitive/motor impairment versus placebo, which demonstrated study validity. In contrast, V117957 at 1mg was not statistically significantly different from placebo. At the supra-therapeutic doses of 6 and 10mg, V117957 was associated with abuse potential and cognitive/motor impairment greater than placebo, yet similar to those of triazolam 0.5 and 1mg. Conclusion Overall, in this valid study, V117957 1mg and placebo were associated with statistically significant lower potential for abuse and reduced cognitive/motor impairment compared with the two supratherapeutic doses of V117957 (6mg, 10mg), and triazolam (0.5mg, 1mg). V117957 1mg met FDA’s statistical criterion for similarity to placebo. Support Funded by Imbrium Therapeutics, a subsidiary of Purdue Pharma L.P.

Evaluation of the abuse potential of pitolisant, a selective H3-receptor antagonist/inverse agonist, for the treatment of adult patients with narcolepsy with or without cataplexy

Objectives To evaluate the human abuse potential of pitolisant, a selective histamine 3 (H3)-receptor antagonist/inverse agonist recently approved by the US Food and Drug Administration for the treatment of excessive daytime sleepiness in adult patients with narcolepsy. Methods Nondependent, recreational stimulant users able to distinguish phentermine HCl 60 mg from placebo in a drug discrimination test were randomized in a four-period, double-blind, crossover design to receive single doses of pitolisant 35.6 mg (therapeutic dose), pitolisant 213.6 mg (supratherapeutic dose), phentermine HCl 60 mg, and placebo. The primary endpoint was maximum effect (Emax) on the 100-point Drug Liking (“at this moment”) visual analog scale. Results In 38 study completers (73.7% male; 65.8% white; mean age, 33.3 years), mean Drug Liking Emax was significantly greater for phentermine versus pitolisant 35.6 mg (mean difference, 21.4; p < 0.0001) and pitolisant 213.6 mg (mean difference, 19.7; p < 0.0001). Drug Liking Emax was similar for pitolisant (both doses) and placebo. Similarly, for key secondary measures of Overall Drug Liking and willingness to Take Drug Again, mean Emax scores were significantly greater for phentermine versus pitolisant (both doses) and similar for pitolisant (both doses) versus placebo. The incidence of adverse events was 82.1% after phentermine HCl 60 mg, 72.5% after pitolisant 213.6 mg, 47.5% after pitolisant 35.6 mg, and 48.8% after placebo administration. Conclusions In this study, pitolisant demonstrated significantly lower potential for abuse compared with phentermine and an overall profile similar to placebo; this suggests a low risk of abuse for pitolisant. Clinical Trial Registration ClinicalTrials.gov NCT03152123. Determination of the abuse potential of pitolisant in healthy, nondependent recreational stimulant users. https://clinicaltrials.gov/ct2/show/NCT03152123.

Human Abuse Potential of Oral NKTR-181 in Recreational Opioid Users: A Randomized, Double-Blind, Crossover Study

Objective To evaluate the human abuse potential, pharmacokinetics, pharmacodynamics, and safety of oral NKTR-181 (oxycodegol), a novel full mu-opioid receptor agonist, relative to oral oxycodone. Design This double-blind, randomized, single-dose, crossover human abuse potential study was conducted in healthy, adult, non–physically dependent recreational opioid users. Setting Inpatient clinical research site. Subjects Seventy-one subjects randomized (95.7% male, 65.2% African American, mean age = 31.7 years). Methods The primary objective was to compare two therapeutic doses of NKTR-181 (400 and 600 mg) with 40 and 60 mg of oxycodone and a supratherapeutic dose (1200 mg) of NKTR-181 with 60 mg of oxycodone using visual analog scale (VAS) ratings for Drug Liking “at this moment” (Drug Liking). Secondary objectives included VAS ratings for other subjective measures, and central nervous system (CNS) mu-opioid effects were assessed using pupillometry. Each subject received single oral doses of five treatments and matching placebo. Results Compared with 40 and 60 mg of oxycodone, the maximum mean Drug Liking score at 400 and 600 mg NKTR-181 was significantly lower, and the rate of onset and extent of Drug Liking for all NKTR-181 doses in the first two hours postdose were also significantly lower. Delayed attenuated Drug Liking and pupillary miosis response following administration of NKTR-181 vs oxycodone were consistent with slower NKTR-181 CNS entry kinetics and mu-opioid receptor binding. No adverse events were rated as severe, and somnolence and dizziness occurred more frequently when subjects received oxycodone. Conclusions NKTR-181 at oral doses of 400 and 600 mg showed significantly fewer and less severe subjective effects accepted as representative of opioid abuse potential, such as lower peak Drug Liking in recreational opioid users, than 40 and 60 mg of oxycodone.

Potential for limited reinforcing and abuse-related subjective effects of intranasal oxytocin

Background: There has been growing interest in using oxytocin as a pharmacotherapy for psychiatric disorders, including substance use disorder. Limited data exist regarding oxytocin’s reinforcing efficacy, which is a necessary consideration for novel pharmacotherapies, especially in substance-using populations. Aims: This study aimed to determine the potential reinforcing effects of intranasally administered oxytocin by assessing behavioral economic demand and subjective effects. Methods: Healthy adults ( n = 23) participated in a double-blind, repeated-measures, laboratory study wherein they received intranasal oxytocin (40 IU) or placebo in a randomized order across two sessions. Participants completed drug purchasing tasks at the conclusion of both sessions. Throughout both sessions, subjective and physiological effects were assessed. Results: Demand-curve analysis of purchasing tasks revealed greater median purchasing for oxytocin relative to placebo. Physiological and subjective effects did not significantly differ between oxytocin and placebo. However, a nonsignificant trend was observed for moderately greater drug liking for oxytocin relative to placebo. There was a significant, positive correlation between the difference in drug liking (between oxytocin and placebo) and the difference in lowest-price purchasing (between oxytocin and placebo). Conclusions: These data suggest the potential for limited reinforcing and abuse-related subjective effects of intranasal oxytocin. Given the small sample, the greater drug liking of oxytocin compared to placebo, and the positive relation between demand and drug liking, it is possible that oxytocin may produce reinforcing effects in some participants. Therefore, additional studies of oxytocin reinforcement are warranted.

Pharmacokinetics and Abuse Potential of Asalhydromorphone, a Novel Prodrug of Hydromorphone, After Intranasal Administration in Recreational Drug Users

Objectives Hydromorphone (HM) is a potent μ-opioid receptor agonist with high susceptibility for abuse. A prodrug of hydromorphone, asalhydromorphone (ASAL-HM), has been designed to deter nonoral forms of abuse associated with hydromorphone. This study evaluated the intranasal (IN) pharmacokinetics and exploratory abuse potential of ASAL-HM compared with HM. Design Single-center, randomized, double-blind, crossover study. Setting Clinical research site. Subjects Healthy adult, nondependent recreational opioid users. Methods Subjects (N = 26) were randomized to receive IN administration of 16.1 mg of ASAL-HM and 8.0 mg of HM (molar-equivalent with respect to hydromorphone). Blood samples were taken through 24 hours postdose, and pharmacodynamic end points (Drug Liking, Feeling High, Take Drug Again, Overall Drug Liking) were assessed through eight hours postdose. Nasal irritation and safety were also assessed. Results Relative to IN HM, the rate (Cmax) and extent (area under the curve [AUC0-last, AUC0-inf]) of exposure to hydromorphone following IN ASAL-HM were reduced by ≥50%. Consistent with these findings, scores on “at-the-moment” (i.e., Drug Liking Emax, High Emax) and retrospective (i.e., Take Drug Again, Overall Drug Liking) end points were statistically significantly lower for IN ASAL-HM, with mean/median differences ranging from 11.4 to 25.0 points. ASAL-HM produced greater nasal-related effects, such as nasal burning and facial pain, and a lower incidence of typical opioid-related adverse events such as euphoria, pruritus, and somnolence. Conclusions The novel hydromorphone prodrug ASAL-HM produced marked reductions in hydromorphone exposure and abuse-related effects following IN administration compared with HM. ASAL-HM has desirable molecular features for incorporation into putative abuse-deterrent immediate-release and extended-release hydromorphone products.

5 Clinical Evaluation of the Abuse Potential of Buprenorphine/Samidorphan Combination

IntroductionBuprenorphine (BUP)/samidorphan (SAM) combination is an opioid system modulator being investigated as an adjunctive treatment for major depressive disorder (MDD). BUP/SAM is a fixed-dose combination of BUP, a partial µ-opioid receptor agonist and κ-opioid receptor antagonist, and SAM, a µ-opioid receptor antagonist added to address the abuse and dependence potential of BUP.1,2Study ObjectiveWe assessed the effects of SAM on the abuse potential of BUP in the BUP/SAM combination in two ways: (1) a human abuse potential (HAP) study in volunteers; and (2) an evaluation of the clinical experience across studies of patients with MDD.MethodsStudy 212 (ClinicalTrials.gov ID: NCT02413281) was a HAP study in nondependent, recreational, adult opioid users. Following a qualification period, participants were randomized to 6 treatments in a blinded, crossover design: placebo (PBO), BUP/SAM at the target therapeutic dose (BUP/SAM 2mg/2mg), at 8mg/8mg and 16mg/16mg , and BUP alone (8mg and 16mg). The primary endpoint was maximum effect (Emax) for “At The Moment” Drug Liking Visual Analog Scale (VAS).The clinical program for BUP/SAM included 4 PBO-controlled studies of patients with MDD (n=961). Pooled safety data were evaluated for adverse events (AEs) that may be associated with abuse, dependence, or withdrawal, as well as for objective signs of withdrawal with the Clinical Opioid Withdrawal Scale (COWS).ResultsIn Study 212 (n=38), Emax Drug Liking VAS scores for the BUP/SAM 2mg/2mg dose were similar to those for PBO (median within-subject difference [90% CI]: 2.5 [0.0–9.0]). Emax Drug Liking VAS scores for all BUP/SAM dose groups, including supratherapeutic doses, were significantly lower than those observed for either of the BUP doses. The supratherapeutic doses of BUP/SAM (8mg/8mg and 16mg/16mg) had higher Emax Drug Liking VAS scores than PBO, but the differences were small.In the MDD controlled studies, the incidence of euphoria-related AEs was low for BUP/SAM 2mg/2mg and PBO (1.6% vs 0.2%, respectively) and there was no evidence of abuse or dependence behavior. Euphoria-related events typically occurred with treatment initiation and resolved with continued treatment. There was minimal evidence of withdrawal by reported AEs or COWS assessment.ConclusionsThese findings indicate that SAM mitigates the abuse potential of BUP in the BUP/SAM combination.Funding Acknowledgements: Alkermes, Inc.

10 Pharmacodynamics and Tolerability of Intranasally Administered Immediate-Release Amphetamine Sulfate Among Recreational Intranasal StimulantUsers

Study ObjectiveDespite increased nonmedical use of ADHD prescription stimulants, there are limited data to inform selection of intranasal doses for abuse-potential evaluations. This study determined a dose of amphetamine sulfate that is tolerable and distinguishable from placebo on pharmacodynamic (PD) measures.MethodsIn this randomized, double-blind, placebo-controlled, dose-escalation study, healthy, nondependent, recreational stimulant users received a single intranasal dose of amphetamine sulfate (20, 30, or 40mg ; n=6 per group) or placebo (n=2 per group). PD and safety were assessed pre-dose and ≤24hours post-dose. Drug Liking was measured using a bipolar Visual Analogue Scale (VAS; 0–100). Dose selection criteria were complete dose insufflation (≥95%); demonstration of peak Drug Liking ≥75 points, and ≥15 points greater than placebo in ≥3 participants receiving active drug; and tolerability.ResultsPeak Drug Liking criteria were met in the 20-, 30-, and 40-mg groups by 2, 0, and 6 participants, respectively. Mean (SD) peak Drug Liking was 62 (13.0), 71 (17.8), and 93 (8.7) for amphetamine sulfate versus 54 (3.5), 76 (34.6), and 51 (0) for placebo in the 20-, 30-, and 40-mg groups, respectively. Thirteen participants experienced mild AEs (n=1, 4, 6, and 1 in 20-, 30-, 40-mg, and placebo groups, respectively), there were no serious or clinically significant AEs. The most common AE was nostril burning sensation (active drug, n=7). There were no instances of an incompletely insufflateddose.ConclusionA 40-mg intranasal dose produced distinguishable PD effects and was well tolerated. This dose has been selected for further abuse-potential evaluations.Funding Acknowledgements: This study was funded by Arbor Pharmaceuticals, LLC.