Buprenorphine reduces methamphetamine intake and drug seeking behavior via activating nociceptin/orphanin FQ peptide receptor in rats

Buprenorphine, which has been approved for the treatment of opioid dependence, reduces cocaine consumption by co-activating μ-opioid receptors and nociceptin/orphanin FQ peptide (NOP) receptors. However, the role of buprenorphine in methamphetamine (METH) reinforcement and drug-seeking behavior remains unclear. This study investigated the effects of buprenorphine on METH self-administration and reinstatement of METH-seeking behavior in rats. We found that buprenorphine pretreatment had an inhibitory effect on METH self-administration behavior, and that buprenorphine at a dose of 0.3 mg/kg could inhibit motivation to respond for METH. Pretreatment with the NOP receptor antagonist thienorphine (0.5 mg/kg) or SB-612111 (1 mg/kg) could reverse the inhibitory effect of buprenorphine (0.1 mg/kg) on the METH self-administration. Moreover, treatment with buprenorphine (0.1 mg/kg and 0.3 mg/kg) significantly reduced the drug-seeking behavior induced by context or by METH priming but failed to reduce the drug-seeking behavior induced by conditional cues. Additionally, the NOP receptor antagonist SB-612111 reversed the inhibitory action of buprenorphine on the drug-seeking behavior induced by METH priming. The results demonstrated that buprenorphine reduced either METH intake or the drug-seeking behavior by activating NOP receptors, providing empirical evidence for the clinical use of buprenorphine in the treatment of METH relapse and addiction.

Cebranopadol, a novel first-in-class drug candidate: Method validation and first exploratory pharmacokinetic study in rabbits

Cebranopadol is a novel, centrally acting, potent, first-in-class analgesic drug candidate with a unique mode of action that combines nociceptin/orphanin FQ peptide receptor and opioid peptide receptor agonism. The present study aimed to develop and validate a novel UHPLC-MS/MS method to quantify cebranopadol in rabbit plasma and to assess its pharmacokinetics in rabbits after subcutaneous (s.c.) administration. Twelve adult females were administered with 200 µg/kg s.c. injection. Blood samples were withdrawn at 15, 30 and 45 min and 1, 1.5, 2, 4, 6, 8, 10 and 24 hr after administration. The plasma samples were extracted with a liquid/liquid extraction. The new analytical method complied with the EMA requirements for the bioanalytical method validation. The method was selective, repeatable, accurate, precise and robust with a lower limit of quantification of 0.1 ng/ml. In all the rabbits, cebranopadol was quantifiable from 0.25 to 10 hr. Mean Cmax and Tmax were 871 ng/ml and 0.25 hr, respectively. Further studies including the i.v. administration are necessary to fully evaluate the pharmacokinetic features of this novel active compound.

Cebranopadol, a Novel First-in-Class Analgesic Drug Candidate: First Experience With Cancer-Related Pain for up to 26 Weeks

CONTEXT

Pain is one of the most prevalent symptoms associated with cancer. Strong opioids are commonly used in the analgesic management of the disease, but carry the risk of severe side effects. Cebranopadol is a first-in-class drug candidate, combining nociceptin/orphanin FQ peptide and opioid peptide receptor agonism. For cancer patients, frequently experiencing multimorbidities and often exposed to polypharmacy, cebranopadol is easy to handle given its once-daily dosing, the small tablet size that enables swallowing, and the option to flexibly titrate to an effective dose.

OBJECTIVES

We assessed the safety and tolerability of prolonged treatment with oral cebranopadol for up to 26 weeks in patients suffering from chronic moderate-to-severe cancer-related pain.

METHODS

This was a non-randomized, multi-site, open-label, single-arm clinical trial with patients who had completed a double-blind trial comparing morphine prolonged release with cebranopadol. In this extension trial, patients were treated with oral cebranopadol for up to 26 weeks.

RESULTS

Cebranopadol was safe and well tolerated in patients with chronic moderate-to-severe pain related to cancer in the dose range tested (200-1000 μg once daily). The median and mean pain levels remained in the range of mild pain during the treatment period.

CONCLUSION

Our data suggest that cebranopadol was safe and well tolerated when administered for up to 26 weeks in patients with chronic cancer-related pain who were previously treated with cebranopadol or morphine prolonged release.

Retest imaging of [11C]NOP-1A binding to nociceptin/orphanin FQ peptide (NOP) receptors in the brain of healthy humans

[(11)C]NOP-1A is a novel high-affinity PET ligand for imaging nociceptin/orphanin FQ peptide (NOP) receptors. Here, we report reproducibility and reliability measures of binding parameter estimates for [(11)C]NOP-1A binding in the brain of healthy humans. After intravenous injection of [(11)C]NOP-1A, PET scans were conducted twice on eleven healthy volunteers on the same (10/11 subjects) or different (1/11 subjects) days. Subjects underwent serial sampling of radial arterial blood to measure parent radioligand concentrations. Distribution volume (VT; a measure of receptor density) was determined by compartmental (one- and two-tissue) modeling in large regions and by simpler regression methods (graphical Logan and bilinear MA1) in both large regions and voxel data. Retest variability and intraclass correlation coefficient (ICC) of VT were determined as measures of reproducibility and reliability respectively. Regional [(11)C]NOP-1A uptake in the brain was high, with a peak radioactivity concentration of 4-7 SUV (standardized uptake value) and a rank order of putamen>cingulate cortex>cerebellum. Brain time-activity curves fitted well in 10 of 11 subjects by unconstrained two-tissue compartmental model. The retest variability of VT was moderately good across brain regions except cerebellum, and was similar across different modeling methods, averaging 12% for large regions and 14% for voxel-based methods. The retest reliability of VT was also moderately good in most brain regions, except thalamus and cerebellum, and was similar across different modeling methods averaging 0.46 for large regions and 0.48 for voxels having gray matter probability >20%. The lowest retest variability and highest retest reliability of VT were achieved by compartmental modeling for large regions, and by the parametric Logan method for voxel-based methods. Moderately good reproducibility and reliability measures of VT for [(11)C]NOP-1A make it a useful PET ligand for comparing NOP receptor binding between different subject groups or under different conditions in the same subject.