Effect of thienorphine on intestinal transit and isolated guinea-pig ileum contraction

What Do We Know about Opioids and the Kidney?

Evidence suggests a link between opioid use and kidney disease. This review summarizes the known renal manifestations of opioid use including its role in acute and chronic kidney injury. Both the direct and indirect effects of the drug, and the context which leads to the development of renal failure, are explored. While commonly used safely for pain control and anesthesia in those with kidney disease, the concerns with respect to side effects and toxicity of opioids are addressed. This is especially relevant with the worldwide increase in the use of opioids for medical and recreational use.

Methyl-orvinol-Dual activity opioid receptor ligand inhibits gastrointestinal transit and alleviates abdominal pain in the mouse models mimicking diarrhea-predominant irritable bowel syndrome

BACKGROUND

Diarrhea-predominant irritable bowel syndrome (IBS-D) is a functional disorder of the gastrointestinal (GI) tract. The major IBS-D symptoms include diarrhea, abdominal pain and discomfort. High density of opioid receptors (ORs) in the GI tract and their participation in the maintenance of GI homeostasis make ORs ligands an attractive option for developing new anti-IBS-D treatments. The aim of this study was to characterize the effect of methyl-orvinol on the GI motility and secretion and in mouse models mimicking symptoms of IBS-D.

METHODS

In vitro, the effects of methyl-orvinol on electrical field stimulated smooth muscle contractility and epithelial ion transport were characterized in the mouse colon. In vivo, the following tests were used to determine methyl-orvinol effect on mouse GI motility: colonic bead expulsion, whole GI transit and fecal pellet output. An antinociceptive action of methyl-orvinol was assessed in the mouse model of visceral pain induced by mustard oil.

RESULTS

Methyl-orvinol (10^-10 to 10^-6M) inhibited colonic smooth muscle contractions in a concentration-dependent manner. This effect was reversed by naloxone (non-selective opioid antagonist) and β-funaltrexamine (selective MOP antagonist). Experiments with a selective KOP receptor agonist, U50488 revealed that methyl-orvinol is a KOP receptor antagonist in the GI tract. Methyl-orvinol enhanced epithelial ion transport. In vivo, methyl-orvinol inhibited colonic bead expulsion and prolonged GI transit. Methyl-orvinol improved hypermotility and reduced abdominal pain in the mouse models mimicking IBS-D symptoms.

CONCLUSION

Methyl-orvinol could become a promising drug candidate in chronic therapy of functional GI diseases such as IBS-D.

Opioid-induced constipation: rationale for the role of norbuprenorphine in buprenorphine-treated individuals

Buprenorphine and buprenorphine–naloxone fixed combinations are effective for managing patients with opioid dependence, but constipation is one of the most common side effects. Evidence indicates that the rate of constipation is lower when patients are switched from sublingual buprenorphine–naloxone tablets or films to a bilayered bioerodible mucoadhesive buccal film formulation, and while the bilayered buccal film promotes unidirectional drug flow across the buccal mucosa, the mechanism for the reduced constipation is unclear. Pharmacokinetic simulations indicate that chronic dosing of sublingually administered buprenorphine may expose patients to higher concentrations of norbuprenorphine than buprenorphine, while chronic dosing of the buccal formulation results in higher buprenorphine concentrations than norbuprenorphine. Because norbuprenorphine is a potent full agonist at mu-opioid receptors, the differences in norbuprenorphine exposure may explain the observed differences in treatment-emergent constipation between the sublingual formulation and the buccal film formulation of buprenorphine–naloxone. To facilitate the understanding and management of opioid-dependent patients at risk of developing opioid-induced constipation, the clinical profiles of these formulations of buprenorphine and buprenorphine-naloxone are summarized, and the incidence of treatment-emergent constipation in clinical trials is reviewed. These data are used to propose a potential role for exposure to norbuprenorphine, an active metabolite of buprenorphine, in the pathophysiology of opioid-induced constipation.

Endogenous opiates and behavior: 2014

This paper is the thirty-seventh consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2014 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (endogenous opioids and receptors), and the roles of these opioid peptides and receptors in pain and analgesia (pain and analgesia); stress and social status (human studies); tolerance and dependence (opioid mediation of other analgesic responses); learning and memory (stress and social status); eating and drinking (stress-induced analgesia); alcohol and drugs of abuse (emotional responses in opioid-mediated behaviors); sexual activity and hormones, pregnancy, development and endocrinology (opioid involvement in stress response regulation); mental illness and mood (tolerance and dependence); seizures and neurologic disorders (learning and memory); electrical-related activity and neurophysiology (opiates and conditioned place preferences (CPP)); general activity and locomotion (eating and drinking); gastrointestinal, renal and hepatic functions (alcohol and drugs of abuse); cardiovascular responses (opiates and ethanol); respiration and thermoregulation (opiates and THC); and immunological responses (opiates and stimulants). This paper is the thirty-seventh consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2014 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (endogenous opioids and receptors), and the roles of these opioid peptides and receptors in pain and analgesia (pain and analgesia); stress and social status (human studies); tolerance and dependence (opioid mediation of other analgesic responses); learning and memory (stress and social status); eating and drinking (stress-induced analgesia); alcohol and drugs of abuse (emotional responses in opioid-mediated behaviors); sexual activity and hormones, pregnancy, development and endocrinology (opioid involvement in stress response regulation); mental illness and mood (tolerance and dependence); seizures and neurologic disorders (learning and memory); electrical-related activity and neurophysiology (opiates and conditioned place preferences (CPP)); general activity and locomotion (eating and drinking); gastrointestinal, renal and hepatic functions (alcohol and drugs of abuse); cardiovascular responses (opiates and ethanol); respiration and thermoregulation (opiates and THC); and immunological responses (opiates and stimulants).

Effects of thienorphine on contraction of the guinea pig sphincter of Oddi, choledochus and gall bladder

Opioid analgesics are widely believed to cause spasm of the bile duct sphincter and so impede bile flow. Thienorphine is a partial opioid agonist that is a good candidate for the treatment of opioid dependence; however, to date, no studies have reported the effects of thienorphine on the function of the biliary tract. This study examined the in vivo effects of thienorphine on the guinea pig isolated sphincter of Oddi, choledochus and gall bladder and on bile flow. The area under the curve (AUC) of isolated sphincter of Oddi was not influenced by thienorphine or buprenorphine, whereas morphine increased the AUC of the isolated sphincter of Oddi in a concentration-dependent manner. Thienorphine and buprenorphine concentration-dependently decreased the AUC of isolated choledochus, while morphine increased the AUC of isolated choledochus. Thienorphine had no effect on the contractile amplitude or basal tension of isolated gall bladder muscle strips. In contrast, buprenorphine and morphine increased the contractile basal tension of isolated gall bladder muscle strips in a concentration-dependent manner. Thienorphine (0.01-1.0mg/kg) had no significant inhibitory effect on bile flow. However, morphine (1.0-10mg/kg) and buprenorphine (1.0mg/kg) significantly inhibited bile flow. The maximum inhibition of bile flow by buprenorphine was 63.9±12.9% and by morphine was 74.1±11.3%. In summary, thienorphine has little influence on the guinea pig isolated sphincter of Oddi, choledochus and gall bladder or on bile flow, which may result in a lack of adverse biliary colic effects.

Novel mixed NOP/MOP agonist BU08070 alleviates pain and inhibits gastrointestinal motility in mouse models mimicking diarrhea-predominant irritable bowel syndrome symptoms

The opioid and nociceptin systems play a crucial role in the maintenance of homeostasis in the gastrointestinal (GI) tract. The aim of this study was to characterize the effect of BU08070, a novel mixed MOP/NOP agonist, on mouse intestinal contractility in vitro and GI motility in vivo in physiological conditions and in animal models mimicking symptoms of irritable bowel syndrome (IBS), including diarrhea and abdominal pain. The effect of BU08070 on muscle contractility in vitro was characterized in the ileum and colon. To assess the effect of BU08070 in vivo, the following parameters were assessed: whole GI transit, gastric emptying, geometric center, colonic bead expulsion, fecal pellet output and time to castor oil-induced diarrhea. The antinociceptive activity of BU08070 was characterized in the mustard oil (MO)-induced abdominal pain model and the writhing test, alone and in the presence of MOP and NOP antagonists. in vitro, BU08070 (10(-10)-10(-6) M) inhibited colonic and ileal smooth muscle contractions in a concentration-dependent manner. in vivo, BU08070 prolonged the whole GI transit and inhibited colonic bead expulsion. The antitransit and antidiarrheal effects of BU08070 were observed already at the dose of 0.1 mg/kg (i.p.). BU08070 reversed hypermotility and reduced pain in mouse models mimicking IBS-D symptoms. Our results suggest that BU08070 has a potential of becoming an efficient drug in IBS-D therapy. Here we also validate mixed NOP/MOP receptor targeting as possible future treatment of functional GI diseases.