The antiseizure medication clobazam can cause potentially severe skin reactions that may lead to injury and death, and the drug label has been changed to reflect this information, according to a statement issued by the Food and Drug Administration on Dec. 3.
The FDA has approved changes to the Warnings and Precautions section of the medication label and the patient Medication Guide to describe the possible reactions: Stevens-Johnson syndrome and toxic epidermal necrolysis. These reactions can occur at any time while a patient is taking clobazam (Onfi), but the risk is greatest during the first 8 weeks of treatment or when the patient has discontinued and then resumed use of the drug, the FDA said.
The label change is based in part on the results of an FDA case series of 20 patients (6 U.S. patients, including 5 children, and 14 foreign patients), in which all cases of Stevens-Johnson syndrome and toxic epidermal necrolysis associated with clobazam resulted in hospitalization; in addition, one case resulted in blindness, and another resulted in death.
"Patients should not stop taking Onfi without first talking to their health care professionals," according to the agency’s statement. "Stopping Onfi suddenly can cause serious withdrawal problems, such as seizures that will not stop, hallucinations (hearing or seeing things that are not real), shaking, nervousness, and stomach or muscle cramps."
The FDA advised health professionals to consider clobazam as a cause in patients with possible drug-induced skin reactions, and to discontinue the drug at the first sign of rash, "unless it is clearly not drug related."
Health professionals should inform patients taking clobazam, a benzodiazepine used to manage seizures in children with severe epilepsy (Lennox-Gastaut syndrome) in combination with other antiepileptic medications, to seek medical attention immediately if they develop a rash, skin blistering or peeling, hives, or sores in the mouth.
"Serious skin reactions have not generally been associated with other benzodiazepines," the FDA noted.
Since clobazam was approved in October 2011 and through September 2013, the FDA says that approximately 31,000 patients received a dispensed prescription for the drug from U.S. outpatient retail pharmacies, which account for the majority of all clobazam bottle sales. The agency also noted that clobazam has been marketed outside the United States for about 40 years under various brand names for the treatment of anxiety and seizures.
To view the complete safety announcement online, visit the FDA's website.