Beware: Adverse Skin Reactions to Alcoholism Treatment Drug

The U.S. Food and Drug Administration (FDA) has issued an alert for healthcare professionals to be aware of the risk for adverse injection site reactions in their patients who receive naltrexone (Vivitrol). Vivitrol is an extended-release version of the generic drug naltrexone marketed by Cephalon Inc. and is manufactured by Cambridge-based Alkermes, Inc. It was approved in 2006 to treat alcohol dependence in patients who show they can abstain from drinking prior to receiving the drug therapy.

The FDA has advised physicians to instruct patients to monitor the injection site of the drug and contact them if they develop pain, swelling, tenderness, hardening, bruising, itching, or redness at the injection site that does not improve or worsens within two weeks. In addition, physicians are directed to refer patients with worsening injection site reactions to a surgeon without delay.

So far, the FDA has received 196 reports of injection site reactions including inflammation, hardening, localized swelling filled with blood, abscess, sterile abscess, and necrosis (localized death of living cells). Sixteen of the patients have required surgical intervention ranging from incision and drainage in for abscesses to extensive surgical removal of foreign material and dead tissue from the wound in order to prevent infection in the cases that resulted in tissue necrosis. Most of these 16 patients were women.

Naltrexone is administered by injection into the gluteus muscles. Naltrexone should not be administered into the veins, under the skin, 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. Vivitrol should be injected into a patient's buttock and doctors need to ensure the needle goes past the fat layer and reaches the gluteus muscles when giving the drug.

According to the FDA, how deep the needle needs to go depends on a patient's gender and weight. Women may be at greater risk for reactions due to typically higher gluteal fat thickness. Candace Steele, spokeswoman for Cephalon, has stated the problems seem to have started when doctors did not properly inject the drug into muscle tissue, thus the problem is believed to be inadvertent. Though it is not known how many patients have received Vivitrol since its FDA approval, Steele said that 70,000 doses have been shipped since 2006.

Vivitrol is injected monthly and is should be used in conjunction with counseling. It works by blocking neurotransmitters in the brain believed to be associated with alcohol dependence, which diminishes the craving for alcohol.
Common side effects of Vivitrol are nausea, headaches and diarrhea. A rare but serious side effect of the drug is liver damage.

Steele noted that risks of skin reactions are mentioned in the product's label, and that "we are committed to working with FDA to make sure physicians understand this information." The FDA said regulators are working with company officials on the creation of a stronger, more prominent warning label.