FDA warns about injection site reactions with naltrexone.

Injectable, extended-release naltrexone (Vivitrol, Cephalon), used for the treatment of alcohol dependence, has been linked to adverse injection-site reactions, some requiring surgery, according to a US Food and Drug Administration (FDA) advisory notice to healthcare professionals released yesterday.

The FDA is recommending that physicians tell patients to monitor the site after injection and to contact their physician "if they develop pain, swelling, tenderness, induration, bruising, pruritus, or redness at the injection site that does not improve or worsens within 2 weeks." Patients should be immediately referred to surgery if the injectionsite reaction appears to be worsening.

Vivitrol is an opioid-receptor blocker administered once monthly by intramuscular gluteal injection for the treatment of alcoholism in patients able to abstain from alcohol use prior to outpatient treatment. To date, the FDA's adverse-event reporting program has received reports of 196 injection-site reactions, including cellulitis, induration, hematoma, abscess, sterile abscess, and necrosis. Of those, 16 required surgical intervention, ranging from incision and drainage for abscesses to extensive surgical debridement for tissue necrosis.

According to the FDA advisory, women may be at higher risk for injection-site reactions due to typically higher fat thickness at the injection site. Vivitrol should be administered only intramuscularly, not intravenously or subcutaneously, and should be injected into alternating buttocks once monthly using a nonstandard 1 1/2-in needle supplied with the medication.

Adverse events associated with the use of naltrexone should be reported to the FDA's MedWatch reporting program by telephone at 1-800-FDA-1088, by fax at 1-800FDA-0178, online at http://www.fda.gov/medwatch/report/hcp.htm, or by mail to 5600 Fishers Lane, Rockville, MD 20852-9787.