Labeling updates and warnings through March 2009 for zonisamide and efalizumab

FDA has issued an alert regarding zonisamide (Zonegran, Eisai; generic zonisamide), which is approved as adjunctive therapy for the treatment of partial seizures in adults with epilepsy. After reviewing clinical data, FDA officials have determined that zonisamide therapy can cause metabolic acidosis, the symptoms of which can include hyperventilation, fatigue, anorexia, cardiac arrhythmias, and stupor. FDA recommends that serum bicarbonate levels should be measured before treatment initiation and during therapy. If metabolic acidosis develops, healthcare professionals should consider reducing the dose or discontinuing zonisamide.

FDA has issued a public health advisory concerning the risk of progressive multifocal leukoencephalopathy (PML) in patients treated with efalizumab (Raptiva, Genentech). Since the approval of this agent in October 2003 for the treatment of moderate-to-severe plaque psoriasis, 3 confirmed cases and 1 possible case of PML have been reported to FDA in patients treated with efalizumab for >3 years. Three of the patients have died. In October 2008, the labeling for efalizumab was updated to include a boxed warning regarding the potential risk of life-threatening infections, including PML. FDA is continuing to monitor the situation. The agency advises that healthcare professionals should monitor patients treated with efalizumab for the onset of neurologic symptoms and discontinue treatment if PML is suspected.