FDA ALERT [08/12/2008]: FDA is notifying healthcare professionals of the risk of adverse injection site reactions in patients receiving naltrexone (Vivitrol). Physicians should instruct patients to monitor the injection site and contact them if they develop pain, swelling, tenderness, induration, bruising, pruritus, or redness at the injection site that does not improve or worsens within two weeks. Physicians should promptly refer patients with worsening injection site reactions to a surgeon.

FDA has received 196 reports of injection site reactions including cellulitis, induration, hematoma, abscess, sterile abscess, and necrosis. Sixteen patients required surgical intervention ranging from incision and drainage in the cases of abscesses to extensive surgical debridement in the cases that resulted in tissue necrosis.

Naltrexone is indicated for the treatment of alcohol dependence in patients who are able to abstain from alcohol in an outpatient setting prior to initiation of treatment. Naltrexone is administered as an intramuscular (IM) gluteal injection. Naltrexone should not be administered intravenously, subcutaneously, or inadvertently into fatty tissue. Healthcare providers should ensure that the naltrexone injection is given correctly with the pre-packaged 1½-inch needle that is specifically designed for this drug.

This information reflects FDA's current analysis of data available to FDA concerning naltrexone (Vivitrol). FDA intends to update this sheet when additional information or analyses become available.