A major goal for the treatment of opioid use disorder is to reduce or eliminate the use of illicit opioids. Buprenorphine, a µ-opioid receptor partial agonist and kappa opioid receptor antagonist, is now being developed as a monthly, sustained-release formulation (RBP-6000). The objective of this study was to demonstrate that RBP-6000 blocks the subjective effects and reinforcing efficacy of the µ-opioid receptor agonist hydromorphone (intramuscularly administered) in subjects with moderate or severe opioid use disorder. Subjects were first inducted and dose stabilized on sublingual buprenorphine/naloxone (8–24 mg daily; dose expressed as the buprenorphine component), then received two subcutaneous injections of RBP-6000 (300 mg) on Day 1 and Day 29. Hydromorphone challenges (6 mg, 18 mg or placebo administered in randomized order) occurred on 3 consecutive days of each study week before and after receiving RBP-6000. Subjects reported their responses to each challenge on various 100-mm Visual Analogue Scales (VAS). Subjects also completed a choice task to assess the reinforcing efficacy of each hydromorphone dose relative to money. At baseline, mean “drug liking” VAS scores for hydromorphone 18 mg and 6 mg versus placebo were 61 mm (95% confidence interval, 52.3–68.9) and 45 mm (95% confidence interval, 37.2–53.6), respectively. After 300 mg RBP-6000 was administered, mean VAS score differences from placebo were less than 10 mm through week 12. The reinforcing efficacy of hydromorphone decreased in a parallel manner. This study demonstrated that RBP-6000 at a 300 mg dose provides durable and potent blockade of the subjective effects and reinforcing efficacy of hydromorphone in subjects with moderate or severe opioid use disorder.
RBP-6000 is a novel sustained-release formulation of buprenorphine for the treatment of opioid use disorder, which has been designed for once-monthly (28 days) subcutaneous (SC) injections. A population pharmacokinetic (PK) model was developed to describe the time course of buprenorphine plasma concentrations after repeated SC injections of RBP-6000 at 50 mg, 100 mg, 200 mg, or 300 mg in treatment-seeking opioid-dependent subjects previously on sublingual buprenorphine (Subutex(®) ) treatment. The μ-opioid receptor occupancy was predicted using a previously developed PK/PD Emax model. The results of the population PK analysis jointly with the predicted level of μ-opioid receptor occupancy provided quantitative criteria for clinical dose selection for RBP-6000: the dose of 300 mg every 28 days seems appropriate for immediately achieving an effective exposure after the first SC injection and to maintain effective levels of exposure during chronic treatment. Furthermore, simulations conducted to evaluate the potential impact of a holiday in drug intake indicated that in the unexpected event of a 2-week holiday, levels of μ-opioid receptor occupancy remained consistently above 70% with no significant loss of drug efficacy. This analysis indicated that RBP-6000 has the potential for becoming an effective treatment for opioid-dependent subjects by addressing compliance issues associated with the current once-a-day treatments.
One may suggest that the adjuvant treatment most likely inhibited the presystemic metabolic enzymes, thus decreasing the intestinal 'first-pass effect' on buprenorphine. Additional studies are now required to further explore the concept of inhibiting presystemic metabolism of buprenorphine by adjuvants to potentially increase the oral bioavailability of buprenorphine.
Background MORF-057 is a potent and selective small molecule inhibitor of the α 4β 7 integrin. Using a receptor occupancy (RO) assay under physiologically relevant conditions, MORF-057 achieves 90% α 4β 7 RO at approximately 10 nM in human whole blood. The current studies evaluate nonclinical pharmacokinetics (PK) and properties of absorption, distribution, metabolism, and excretion (ADME) to enable dose/exposure projection to humans. Methods PK studies were conducted in mouse, rat, dog, and monkey following intravenous (IV) and oral administration. ADME studies were conducted in vitro and in rats using carbon-14 [14C] labeled MORF-057. MORF-057 levels were quantified using liquid chromatography coupled with tandem mass spectrometry. Human PK was predicted based on body weight allometry, well-stirred and semi-physiological models. Results MORF-057 exhibited low to moderate clearance (CL) in animals with species dependent volume of distribution (Vdss) resulting in half-lives of 1.1 to 2.7 hours (Table 1). Following an oral dose, absorption was high with bioavailability ranging from 15% to 49%. MORF-057 is highly protein bound and distribution of [14C]MORF-057 derived radioactivity in rat was predominantly in the small intestine wall, liver, and stomach wall. Rifampin, an inhibitor of organic anion transporting polypeptides, decreased MORF-057 clearance by 3-fold in monkeys suggesting MORF-057 elimination involves hepatic uptake transport. MORF-057 is further cleared via CYP3A metabolism followed by biliary/fecal elimination of metabolites. MORF-057 is predicted to have moderate bioavailability (40%) and CL (6.5 mL/min/kg) in humans. Wajima transformation shows good agreement of the normalized PK across animal species, with a predicted human concentration-time profile supporting >90% α 4β 7 RO at trough following 200 mg twice daily dose (Figure 1). Conclusion These data demonstrate that MORF-057 is well absorbed and PK properties in animals support the potential for achieving high α4β7 RO following oral administration in humans. These nonclinical results provided a basis for the progression of MORF-057 into a first-in-human Phase 1 clinical study assessing safety, pharmacokinetics, and receptor occupancy (results being reported separately).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.