Zyvox, used to treat some types of drug-resistant bacteria including MSRA or methicillin-related Staphylococcus aureus, skin infections and nosocomial pneumonia, can interact with the antidepressants to cause a toxic reaction known as serotonin syndrome in which excess amounts of the chemical build up in the brain, according to the FDA.
Some deaths among patients who suffered such a reaction were reported to the FDA’s adverse-event database, the agency said. Pfizer, based in New York, reported $1.18 billion in revenue from Zyvox last year.
Confusion, memory issues, hyperactivity, excessive sweating and muscle twitching are among the symptoms of excess serotonin levels. Patients taking psychiatric drugs shouldn’t stop using them without first consulting a health-care professional, the FDA said.
The current U.S. package insert for Zyvox “already includes prominent information regarding the potential for serotonergic interactions, the risk of serotonin syndrome and the need for careful observation of patients prescribed Zyvox who are on such agents,” Kristen Neese, a Pfizer spokeswoman, said today in an e-mail. The company hasn’t identified any new safety signals related to those drug interactions, she said.
“In an ongoing commitment to ensure patient safety, Pfizer continually monitors all relevant safety information including information pertaining to the concomitant use of Zyvox and serotonergic antidepressant medications,” Neese said.