Elliot Ehrich

A Pilot Evaluation of the Safety and Tolerability of Repeat Dose Administration of Long‐Acting Injectable Naltrexone (Vivitrex®) in Patients With Alcohol Dependence

BACKGROUND : Oral naltrexone is currently used as part of a treatment regimen for alcohol-dependent patients, but its clinical utility is hampered by poor patient adherence. A long-acting injectable naltrexone formulation (Vivitrex) was designed to facilitate patient adherence by providing an extended duration of therapeutic naltrexone over 1 month, thereby eliminating the need for daily dosing. METHODS : A multicenter, randomized, double-blind, placebo-controlled pilot study was conducted to evaluate the safety and tolerability of intramuscular repeat dose administration of this extended-release naltrexone formulation in DSM-IV alcohol-dependent patients. Thirty patients were randomized to treatment with injectable naltrexone (400 mg; n = 25) or a matching placebo injection (n = 5) and were dosed once every 28 days over 4 months. Psychosocial treatment was offered to patients in both treatment groups. Outcome measures related to drinking activity and trough plasma concentrations of naltrexone and its primary metabolite, 6-beta-naltrexol, were evaluated. RESULTS : Injectable naltrexone was generally safe and well tolerated. Reported adverse events were mild to moderate and resolved without intervention; only two patients discontinued due to adverse events. The most common adverse events (nausea and headache) occurred at a similar rate for patients in both treatment groups. Pharmacokinetic analysis confirmed that therapeutic levels of naltrexone were delivered throughout the four 1-month treatment cycles. CONCLUSIONS : The results of this pilot study provide the basis and methods for a larger, more definitive trial to determine the utility of this long-acting injectable naltrexone formulation in the treatment of alcohol-dependent patients.

Evaluation of Opioid Modulation in Major Depressive Disorder

Although opioids have known antidepressant activity, their use in major depressive disorder (MDD) has been greatly limited by risk of abuse and addiction. Our aim was to determine whether opioid modulation achieved through a combination of a μ-opioid partial agonist, buprenorphine (BUP), and a potent μ-opioid antagonist, samidorphan (SAM), would demonstrate antidepressant activity without addictive potential. A placebo-controlled crossover study assessed the opioid pharmacodynamic profile following escalating doses of SAM co-administered with BUP in opioid-experienced adults. A subsequent 1-week, placebo-controlled, parallel-group study was conducted in subjects with MDD and an inadequate response to standard antidepressant therapy. This second study evaluated safety and efficacy of ratios of BUP/SAM that were associated with partial and with maximal blockade of opioid responses in the initial study. Pupillometry, visual analog scale assessments, and self-reported questionnaires demonstrated that increasing amounts of SAM added to a fixed dose of BUP resulted in dose-dependent reductions in objective and subjective opioid effects, including euphoria and drug liking, in opioid-experienced adults. Following 7 days of treatment in subjects with MDD, a 1 : 1 ratio of BUP and SAM, the ratio associated with maximal antagonism of opioid effects, exhibited statistically significant improvement vs placebo in HAM-D17 total score (p=0.032) and nearly significant improvement in Montgomery-Åsberg Depression Rating Scale (MADRS) total score (p=0.054). Overall, BUP/SAM therapy was well tolerated. A combination of BUP and SAM showed antidepressant activity in subjects with MDD. Balanced agonist–antagonist opioid modulation represents a novel and potentially clinically important approach to the treatment of MDD and other psychiatric disorders.

Opioid Modulation With Buprenorphine/Samidorphan as Adjunctive Treatment for Inadequate Response to Antidepressants: A Randomized Double-Blind Placebo-Controlled Trial

OBJECTIVE Major depressive disorder has been associated with dysregulation of the endogenous opioid system. The authors sought to determine whether opioid modulation achieved through administration of ALKS 5461, a combination of a μ- and κ-opioid partial agonist, buprenorphine, and a μ-opioid antagonist, samidorphan, would exhibit antidepressant activity in patients with major depression. METHOD A multicenter, randomized, double-blind, placebo-controlled, two-stage sequential parallel comparison design study was conducted in adults with major depression who had an inadequate response to one or two courses of antidepressant treatment. Participants were randomly assigned to receive adjunctive treatment with 2 mg/2 mg of buprenorphine/samidorphan (the 2/2 dosage group), 8 mg/8 mg of buprenorphine/samidorphan (the 8/8 dosage group), or placebo. Antidepressant effect was measured based on change from baseline to the end of 4 weeks of treatment on the 17-item Hamilton Depression Rating Scale (HAM-D), the Montgomery-Åsberg Depression Rating Scale (MADRS), and the Clinical Global Impressions severity scale (CGI-S). RESULTS Compared with the placebo group, there were significantly greater improvements in the 2/2 dosage group across the three depression outcome measures (HAM-D: -2.8, 95% CI=-5.1, -0.6; MADRS: -4.9, 95% CI=-8.2, -1.6; CGI-S: -0.5, 95% CI=-0.9, -0.1). There was also evidence of improvement in the 8/8 dosage group, although it did not achieve statistical significance. Overall, the buprenorphine/samidorphan combinations were well tolerated, and there was no evidence of opioid withdrawal on treatment discontinuation. CONCLUSIONS The buprenorphine/samidorphan combination is a novel and promising candidate for treatment of major depressive disorder in patients who have an inadequate response to standard antidepressants.

A Randomized, Double-Blind, Placebo-Controlled Trial of Aripiprazole Lauroxil in Acute Exacerbation of Schizophrenia

OBJECTIVE This study evaluated the efficacy, safety, and tolerability of aripiprazole lauroxil, a novel long-acting injectable atypical antipsychotic, for the treatment of schizophrenia. METHOD An international multicenter, randomized, double-blind, placebo-controlled trial was conducted between December 2011 and March 2014. Patients (N = 623) aged 18 to 70 years with schizophrenia (DSM-IV-TR criteria), experiencing an acute exacerbation, were randomized in a 1:1:1 ratio to receive gluteal intramuscular injection of aripiprazole lauroxil 441 mg, aripiprazole lauroxil 882 mg, or matching placebo once monthly for 12 weeks. The primary efficacy outcome was change in Positive and Negative Syndrome Scale (PANSS) total score from baseline to day 85. The Clinical Global Impressions-Improvement scale (CGI-I) score at day 85 was the secondary efficacy outcome. Safety and tolerability were assessed. RESULTS The PANSS total score (mean ± standard error [SE]) improved significantly from baseline to day 85 in the aripiprazole lauroxil 441 mg and 882 mg groups, with placebo-adjusted differences of -10.9 ± 1.8 (P < .001) and -11.9 ± 1.8 (P < .001), respectively. Significant (P ≤ .004) improvements in both active treatment groups were demonstrated as early as day 8 and continued throughout the treatment period. The proportion of patients who were very much or much improved on the CGI-I was significantly greater with aripiprazole lauroxil 441 mg and 882 mg treatment versus placebo (P < .001). The most common treatment-emergent adverse events were insomnia, akathisia, headache, and anxiety. The incidence of injection site reactions was low, predominantly described as injection site pain, and was associated with the first injection. CONCLUSIONS Aripiprazole lauroxil demonstrated robust efficacy for treatment of patients experiencing acute exacerbation of schizophrenia. The improvement in psychotic symptoms was statistically significant and clinically meaningful. Symptom improvement occurred rapidly after initiation of aripiprazole lauroxil treatment and was maintained throughout the study. Both aripiprazole lauroxil 441 mg and 882 mg doses were well tolerated. These results support aripiprazole lauroxil as an important new treatment option for schizophrenia. TRIAL REGISTRATION ClinicalTrials.gov identifier: NCT01469039; Clinicaltrialsregister.eu identifier: 2012-003445-15.

Pharmacokinetics of Long‐Acting Naltrexone in Subjects With Mild to Moderate Hepatic Impairment

Long‐acting naltrexone is an extended‐release formulation developed with the goal of continuous naltrexone exposure for 1 month for the treatment of alcohol dependence. The influence of mild and moderate hepatic impairment on naltrexone pharmacokinetics following long‐acting naltrexone 190‐mg administration was assessed. Subjects with mild (Child‐Pugh grade A) and moderate (Child‐Pugh grade B) hepatic impairment (n = 6 per group) and matched control subjects (n = 13) were enrolled. Naltrexone and 6β‐naltrexol concentrations were determined over a period of 63 days following a single intramuscular dose. Naltrexone and 6β‐naltrexol concentrations were detected in all subjects through 28 days. Total exposure (AUC0‐∞) of naltrexone and 6β‐naltrexol was similar across all groups. The long apparent half‐lives of naltrexone and 6β‐naltrexol (5–8 days) were attributed to the slow release of naltrexone (long‐acting naltrexone exhibits absorption rate‐limited elimination or “flip‐flop” kinetics); elimination was not altered in subjects with hepatic impairment. Based on pharmacokinetic considerations, the dose of long‐acting naltrexone does not need to be adjusted in patients with mild or moderate hepatic impairment.

A placebo-controlled pilot study of the novel opioid receptor antagonist ALKS-33 in binge eating disorder.

OBJECTIVE To assess preliminarily the effectiveness of a novel opioid antagonist, ALKS-33, in binge eating disorder (BED). METHOD In this randomized, placebo-controlled, flexible dose, proof-of-concept trial, 62 outpatients with BED and obesity received ALKS-33 (N = 26) or placebo (N = 36) for 6 weeks. Outcome measures of binge eating, body weight, and eating pathology were assessed. RESULTS A large decrease in binge eating episode frequency was observed following both ALKS-33 and placebo treatment. There was no significant difference between treatment groups in binge eating episode frequency or any other measure of binge eating, body weight, or eating pathology. DISCUSSION In this preliminary proof-of-concept study in BED, ALKS-33 did not separate from placebo. Although a failed trial cannot be excluded, the finding is consistent with earlier observations in bulimia nervosa with other opioid antagonists and suggests ALKS-33, at least when administered daily for 6 weeks, may not be efficacious for BED.

Relative bioavailability and safety of aripiprazole lauroxil, a novel once-monthly, long-acting injectable atypical antipsychotic, following deltoid and gluteal administration in adult subjects with schizophrenia.

Aripiprazole lauroxil is a linker lipid ester of aripiprazole for extended-release intramuscular (IM) injection. This multicenter, randomized, open-label study evaluated the pharmacokinetics (PK), relative bioavailability, and tolerability of a single IM deltoid or gluteal injection of aripiprazole lauroxil in adult subjects with chronic stable schizophrenia or schizoaffective disorder. Forty-six subjects were randomized 1:1 to aripiprazole lauroxil 441 mg IM in the deltoid or gluteal muscle. Samples were collected through 89 days post-dose to measure levels of aripiprazole lauroxil, N-hydroxymethyl aripiprazole, aripiprazole, and dehydro-aripiprazole. Forty-three (93.5%) subjects completed all study assessments; most were CYP2D6 extensive or immediate metabolizers (96%); two (4%) were poor metabolizers. The PK of aripiprazole following aripiprazole lauroxil was characterized by a steady rise in plasma concentrations (Tmax 44-50 days), a broad peak, and prolonged exposure attributable to the dissolution of aripiprazole lauroxil and formation rate-limited elimination of aripiprazole (t1/2=15.4-19.2 days). Deltoid vs. gluteal administration resulted in slightly higher Cmax aripiprazole concentrations [1.31 (1.02, 1.67); GMR 90% CI]; total exposure (AUCinf) was similar between sites of administration [0.84 (0.57, 1.24)]. N-hydroxymethyl-aripiprazole and dehydro-aripiprazole exposures were 10% and 33-36%, respectively, of aripiprazole exposure following aripiprazole lauroxil. The most common adverse events were injection site pain in 20 subjects (43.5%) and headache in 6 subjects (13.0%) of mild intensity occurring at a similar rate with deltoid and gluteal administration. Exposure ranges with deltoid and gluteal administration overlapped, suggesting that these sites may be used interchangeably. Despite a higher incidence of adverse events, deltoid muscle provides a more accessible injection site and could facilitate patient acceptance.

Use of Remifentanil in a Novel Clinical Paradigm to Characterize Onset and Duration of Opioid Blockade by Samidorphan, a Potent μ-Receptor Antagonist.

Abstract A novel clinical study design was used to evaluate the blockade of a selective short-acting &mgr;-opioid agonist (remifentanil) in 24 opioid-experienced subjects. Samidorphan (3-carboxamido-4-hydroxynaltrexone) is a novel opioid modulator with &mgr;-antagonist properties. Objective (pupil diameter) and subjective (visual analog scale) responses to repeated remifentanil and saline infusion challenges were assessed after single oral administration of placebo (day 1) and samidorphan (day 2). Complete blockade persisted with samidorphan for 24 hours for pupil miosis and 48 hours for the drug liking visual analog scale. Samidorphan effects persisted beyond measurable samidorphan exposure (t½ = 7 hours). Samidorphan was associated with complete blockade of remifentanil, and the duration supports daily administration. This study used a novel approach with multiple administrations of remifentanil to successfully demonstrate a durable effect with samidorphan and a rapid and potent blockade of physiological and subjective &mgr;-opioid effects.

Effect of Aripiprazole Lauroxil on Metabolic and Endocrine Profiles and Related Safety Considerations Among Patients With Acute Schizophrenia.

OBJECTIVE Aripiprazole lauroxil, a long-acting injectable antipsychotic, demonstrated safety and efficacy in treating symptoms of schizophrenia in a double-blind, placebo-controlled trial. Because the metabolic profile of antipsychotics is an important safety feature, the effects of aripiprazole lauroxil on body weight, endocrine and metabolic profiles, and safety were examined in a secondary analysis. METHODS Patients with schizophrenia (DSM-IV-TR criteria) were randomly assigned to aripiprazole lauroxil 441 mg, aripiprazole lauroxil 882 mg, or placebo intramuscularly once monthly between December 2011 and March 2014. Changes in body weight, body mass index, fasting blood glucose and serum lipids, glycosylated hemoglobin (HbA1c), and prolactin over 12 weeks were assessed. The incidence of treatment-emergent adverse events (AEs) was evaluated. RESULTS Among 622 randomized patients, no clinically relevant changes from baseline to week 12 were observed for any serum lipid, lipoprotein, plasma glucose, or HbA1c value with placebo or either dose of aripiprazole lauroxil. Both doses of aripiprazole lauroxil were associated with reductions in mean prolactin levels, whereas placebo treatment was not. The mean (standard deviation) change from baseline for body weight was 0.74 (3.9) kg, 0.86 (3.7) kg, and 0.01 (3.6) kg for aripiprazole lauroxil 441 mg, aripiprazole lauroxil 882 mg, and placebo groups, respectively. AEs related to metabolic parameters were reported in 2.4%, 1.4%, and 2.4% of patients in the aripiprazole lauroxil 441 mg, aripiprazole lauroxil 882 mg, and placebo groups, respectively. CONCLUSIONS Aripiprazole lauroxil was well tolerated, with a low-risk metabolic profile relative to published data for other antipsychotics. Changes similar to those observed with placebo were observed in the aripiprazole lauroxil groups for metabolic parameters, with modest weight gain in the active treatment groups over the 12-week course. TRIAL REGISTRATION ClinicalTrials.gov identifier: NCT01469039.

Single- and Multiple-dose Pharmacokinetics of Samidorphan, A Novel Opioid Antagonist, in Healthy Volunteers

PURPOSE Samidorphan (3-carboxamido-4-hydroxy naltrexone) is a novel opioid receptor antagonist that is currently in clinical development. The oral dose pharmacokinetics, safety, and tolerability of samidorphan were evaluated in 2 double-blind, placebo-controlled, randomized studies in healthy adults. METHODS The first study investigated single, ascending doses of 3.7 to 55.7 mg of samidorphan in 16 healthy adults; the second study evaluated multiple ascending doses of 10 or 20 mg of samidorphan administered for 7 days in 30 healthy adults. FINDINGS Across the two studies, 39 of 46 subjects were male; 32 were white, 11 were black, and 3 were hispanic. Mean age was 34.9 years and mean weight was 84.2 kg. In both studies, samidorphan was rapidly absorbed, with a Tmax of 1 hour, and AUC increased with increasing dose. Samidorphan plasma levels declined in a monoexponential manner, with a half-life of ~7 to 9 hours. After multiple doses, steady state was approached by day 6 and achieved by day 7 after the 10-mg dose, but steady state was not reached for the 20-mg dose. Accumulation was low, with accumulation ratios <1.65. In both studies, samidorphan was generally well tolerated, with somnolence reported as the most common adverse event. IMPLICATIONS In these single- and multiple-dose studies in healthy volunteers, samidorphan exhibited a pharmacokinetic profile consistent with once-daily dosing. ClinicalTrials.gov identifier: NCT00800319.