Feb. 27 (UPI) -- A failed drug compound tested on people with osteoarthritis pain might prevent opioid tolerance and physical dependence when used with opioid-based pain medications, according to a study.
Researchers at Indiana University found the compound appears to block neuropathic pain and decrease signs of opioid dependence, according to findings published in the February issue of the journal Molecular Pharmacology.
Eli Lilly's trials of the drug for osteoarthritis pain were unsuccessful. At the time, the drug's use in treating other kinds of pain and lessening opioid dependence wasn't tested. But researchers opted to start testing it after they found it interacted with the body on a target known to be involved with pain relief.
The need for more effective painkillers that carry fewer dangers of misuse and abuse than opioids is great. The Centers for Disease Control and Prevention report that, in 2016, more than 11 million people abused prescription drugs, including opioids, and more 64,000 Americans died from drug overdoses.
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"The potential to quickly begin using this compound in combination with opioid-based medication to treat pain and reduce addiction makes this discovery very significant," lead investigator Andrea G. Hohmann, a professor in the IU Bloomington College of Arts and Sciences' Department of Psychological and Brain Sciences, said in a press release. "We already know this drug is safe for use in people, so moving into human trials will not require as many regulatory hurdles."
To test its effects and potential for addiction, Indiana University scientists administered the compound, called LY2828360, and the opioid drug morphine to male mice with neuropathic pain.
Initially, morphine reduced pain in the mice, but they quickly developed tolerance to the drug's effectiveness. Similarly, people require higher doses of opioid over time because they build up tolerance.
When a low dose of the experimental drug was combined with morphine, however, the mice no longer became tolerant to morphine -- even after the experimental drug was discontinued. The researchers also found the compound reduced pain on its own at higher doses.
Mice also were given morphine alone or morphine in combination with the experimental drug, and then treated with naloxone. Naloxone is regularly used to block the effect of opioids and induces opioid withdrawal symptoms. In the experiment, the experimental drug also decreased the severity of withdrawal symptoms.
