Effects of the Mu Opioid Receptor Positive Allosteric Modulator BMS-986122 On Opioid Efficacy in Rat Neuropathic Pain States

BackgroundNeuropathic pain is a major source of disability and distress with few pharmacological options for treatment. Opioid drugs can be effective, but high doses are needed, leading to unwanted effects. BMS-986122 is a positive allosteric modulator of the mu opioid receptor that potentiates acute opioid antinociception without increasing opioid-induced constipation, reward, or respiratory depression. Therefore, we asked if BMS-986122 could increase the effects of low-dose opioid analgesics in chronic neuropathic pain. MethodsWe employed the spared nerve injury and tibial neuroma models in rats and assessed the tactile hypersensitivity of the hind paw and site of neuroma, respectively. ResultsAdministration of low doses of (R)-methadone, morphine, or buprenorphine slightly reduced the tactile hypersensitivity of the hind paw the in spared nerve injury model. Pretreatment with BMS-986122 significantly enhanced the reversal of hypersensitivity, reaching the effect of high-dose gabapentin, a standard of care in neuropathic pain. Pretreatment with BMS-986122 similarly increased the anti-allodynic effects of low dose (R)-methadone on neuroma pain. A similar effect of (R)-methadone in the absence of BMS-986122 was only observed at a dose where respiratory distress was seen. ConclusionsThese findings show that allosteric modulators of the mu opioid receptor such as BMS-986122 can enhance opioid activity that could translate to a safe and effective treatment for chronic neuropathic pain.