Case Report of Severe Injection Site Reaction Associated with Intramuscular Naltrexone

Problem statement: To report a case of severe injection site reaction at the site of an IM naltrexone injection in a 30 year old female. Approach: A 30 year old female, being treated with naltrexone extended-release injectable suspension for alcohol dependence, presented with a mass on her left upper gluteal area at the site of injection. The injectable naltrexone was discontinued, however the mass persisted. Upon referral to a general surgeon, it was determined that the mass was a hematoma or subcutaneous tissue necrosis secondary to naltrexone injection. Results: Naltrexone extended-release injection is Food and Drug Administration (FDA) approved for maintaining abstinence in alcohol dependency. It has been shown to increase the time to relapse compared to placebo, decrease the number of drinking days compared to placebo and decrease the number of heavy drinking days as compared to placebo. There have been no published case reports of severe injection site reaction associated with injectable naltrexone; however there has been a MedWatch alert warning of the risk of injection site reactions after receiving the injection. Conclusion: Patients receiving the injectable naltrexone should carefully monitor the injection site for signs of injection site reaction.