A new study reveals promising potential for the use of nalfurafine, an anti-itch medication, as an add-on to opioid pain treatment.
Pain is a diverse experience that comes in many different forms, as not all pain feels the same. Pain from a sunburn feels different than pain from a headache. Not only is pain itself diverse, but so are the pain treatments used to manage it. Different pain relievers target different parts and pathways of the nervous system to reduce the sensation of pain, with some pain relievers being more effective than others.
Some of the most well-known and effective pain relievers widely used today are opioids, such as morphine. Unfortunately, the use of opioids also comes with a number of side effects, such as constipation, nausea, and the risk of addiction. As opioid addiction has become a health crisis, there is renewed interest in finding opioid-sparing pain relievers or alternatives. In a new study published in The Journal of Pharmacology and Experimental Therapeutics, researchers from the United States studied the potential role that the anti-itch medication, nalfurafine, could have in pain management and the fight against opioid over-prescription.
In the study, the researchers used mouse models to test the effectiveness of morphine alone to treat pain versus morphine in combination with nalfurafine. Their test included administrations of a range of doses, in order to determine the lowest effective dose to treat pain. The various regimens were then compared to evaluate which provided the most effective pain relief.
The researchers found that the use of a small amount of nalfurafine as a supplement together with a lower dose of morphine produced the same pain relief as a much larger dose of morphine. With the discovery, the idea is that patients would only need a low dose of nalfurafine with a low dose of morphine to achieve the same pain relief as a high dose of morphine, thereby reducing the risk of addiction and substance abuse.
Although nalfurafine is considered an opioid, the key difference is the pharmacology of how it works in the body. Unlike morphine, which targets mu opioid receptors that reduce pain and activates the reward pathway that leads to addiction, nalfurafine targets a different opioid receptor, kappa, which reduces pain without the reward feedback. Further, nalfurafine didn’t appear to cause the same side effects, such as profound dysphoria (i.e., state of uneasiness, unhappiness, or dissatisfaction), that many other kappa opioid receptors did in early clinical studies.
The findings of this study suggest that nalfurafine may be a potential add-on to highly addictive opioid drugs for pain relief. The supplementation of nalfurafine could potentially reduce the dose of addictive opioids and reduce the risk of addiction. Prevention is important in the fight against opioid addiction and nalfurafine may just be a key factor in achieving that.
Written by Maggie Leung, PharmD
Kaski, S. W., White, A. N., Gross, J. D., Trexler, K. R., Wix, K., Harland, A. A., … Setola, V. (2019). Preclinical Testing of Nalfurafine as an Opioid-sparing Adjuvant that Potentiates Analgesia by the Mu Opioid Receptor-targeting Agonist Morphine. Journal of Pharmacology and Experimental Therapeutics, 371(2), 487–499. doi: 10.1124/jpet.118.255661
Fighting opioids with an unlikely supplemental painkiller: Anti-itch medicine. (2019, November 21). Retrieved from https://www.eurekalert.org/pub_releases/2019-11/wvu-fow112119.php.
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