New Alternatives to Morphine May Reduce Pain Sensitivity, With Limited Side Effects
Zadina JE, Nilges MR, Morgenweck J, Zhang X, Hackler L, Fasold MB. Endomorphin analog analgesics with reduced abuse liability, respiratory depression, motor impairment, tolerance, and glial activation relative to morphine. Neuropharmacology. 2015 Dec 31;105:215-227. doi: 10.1016/j.neuropharm.2015.12.024. [Epub ahead of print]
Morphine and other opioids are such powerful painkillers that they are commonly used for a variety of pain conditions, despite the fact that they have quite a few negative side effects, including mental and physical impairment, poor respiration, drug tolerance, overdosing, and potential for abuse. Now, there is a new class of drugs that are similar to morphine that may offer comparable pain relief but with fewer of these unwanted effects. Four of these drugs, known as endomorphin analogs, were assessed by researchers in this animal study. According to researchers, these drugs offered a reduction in pain sensitivity that was equal to or greater than that of morphine, yet with a reduction or elimination of specific side effects. At doses similar to morphine, rats receiving the endomorphin analogs had less respiratory depression, tolerance, impaired physical coordination, and hyperalgesia (a pain sensitivity phenomenon associated with opioid use). Moreover, the drugs seem to have less abuse potential, judging from results of tests where rats were allowed to self-administer doses of the drugs. Finally, results of brain studies suggested these endomorphin analogs have different mechanisms of action compared with morphine. Based on these results, researchers said the novel endomorphin analogs have the potential to one day become “gold standard” drugs for pain relief.