Mu 1 opioid receptor (OPRM1) is a pharmacodynamic receptor that is partly responsible for opioid effectiveness. OPRM1 is most commonly associated with pain sensitivity, substance dependence, and abuse. The most analyzed genetic variant in the pain field, known as c.118A>G, has shown an association with opioid effectiveness, but the correlation is small and not always replicated in studies. The c.118A>G variant has also shown a correlation with naltrexone (Vivitrol®) efficacy in the treatment of alcoholism and addiction risk to opioids. Genetic variant tested for OPRM1 is c.118A>G.
Indications for OPRM1 Testing
Patients beginning naltrexone treatment for alcohol dependence would be good candidates for OPRM1 testing. Testing may also help predict opioid response and dose requirements. In patients of Asian descent, testing may help assess opioid addiction risk.