The Emergence of Treatment for OIH (Opioid Induced Hyperalgesia)

Recently, the word “opioid” seems to cause people to immediately associate it with our nation’s current opioid epidemic. However, there are still patients who are prescribed opioids to manage their pain after operations and/or surgical procedures. When they are prescribed, opioid drugs are only dispensed in small amounts and can alleviate major pain or discomfort. Addiction is a major concern for health care professionals across the country at this point because the prescriptions can be easily abused and illegal opioids, such as heroin, codeine, and morphine have invaded the everyday lives of Americans of every community. 

Unfortunately, what many are unaware of is the long-term effect of opioid use. Over time, and/or with careless prescription assignment, the drug that was initially prescribed to alleviate major pain can actually cause hypersensitivity to pain or noxious stimuli in general. The condition is called opioid-induced hyperalgesia or OIH for short. Where an individual’s pain threshold or tolerance level was once stable, people suffering from OIH have decreased pain thresholds. This means that the individual is incredibly more sensitive and it takes less stimulus to cause a painful event. 

Dr. Folabomi Oladosu warns that a major concern for medical professionals when dealing with OIH is the fact that opioids are very effective at treating pain and are one of the few options available. However, there is a paradox of treating a sensitivity disorder with the same drug, just in higher doses, is incredibly dangerous and can lead to addiction. 

In her research, Dr. Oladosu and her team conducted the first study observing the behavior of MOR1K opioid receptor in OIH. Using three diverse mouse types, all administered morphine, experimenters observed the responses shown after being given a painful stimulus when their MOR1K opioid receptors were compromised and/or altered. The conclusion made was that MOR1K was the most probable factor in OIH development. 

Where Dr. Oladosu’s research focused on manipulating the opioid receptor MOR1K, Dr. Yeon-Dong Kim from South Korea and his research is focused on an increase in the pain inhibiting neurotransmitters using Dexmedetomidine. Dexmedetomidine is a very selective alpha 2 agonist drug that increases the amount of pain inhibiting neurotransmitters. 

In a totally different method of experiment from Dr. Oladosu, Dr. Kim enlisted ninety women who were to undergo hysterectomies and administered either an initial dose of Dexmedetomidine followed by undisrupted infusion during the procedure, OR a saline placebo prior to general anesthesia and operative Remifentanil. What researchers found were that post-operative hyperalgesic thresholds were significantly lower in the patients treated with Dexmedetomidine compared to patients treated with a placebo and general anesthesia. 

I believe both studies are compelling. From opposite sides of the globe, researchers are questing for a solution to OIH. What’s more interesting is that Drs. Oladosu and Kim experimented with both the ligands and receptors of the pain signaling pathway of OIH. 

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Work Referenced 

Anderson, Pauline. “Possible New Treatment for Opioid-Induced Hyperalgesia.” Medscape , 15 Apr. 2013, www.medscape.com/viewarticle/782526#vp_2.

Oladosu, Folabomi A., et al. “Mu Opioid Splice Variant MOR-1K Contributes to the Development of Opioid-Induced         Hyperalgesia.” PLOS ONE, Public Library of Science, 13 Aug. 2015, journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0135711.

SUPPLEMENTAL READING and IMAGE REFERENCE

Servick, Kelly, et al. “Why Painkillers Sometimes Make the Pain Worse.” Science | AAAS, AAAS, 3 Nov. 2016, 2:00PM, www.sciencemag.org/news/2016/11/why-painkillers-sometimes-make-pain-worse.  

[ SARAH ALHARSHA ]