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Aug 15 2011

Pfizer’s Zyvox and Antidepressants May Be Fatal Combination

Posted in Community Service, Product Liability

Zyvox antibiotic a highly effective drug may cause negative reactions in patients receiving medical treatment for depression, says Alabama liability attorney Keith T. Belt

Pfizer Inc. (PFE)’s Zyvox antibiotic (a reported $1.18 billion in revenue drug last year) can cause potentially fatal central nervous system reactions in patients who also take antidepressants that increase levels of the brain chemical serotonin, U.S. regulators said.

Pfizer’s Zoloft and Pristiq, Eli Lilly & Co. (LLY)’s Cymbalta and GlaxoSmithKline Plc (GSK)’s Paxil and Wellbutrin are among 29 psychiatric drugs that patients may need to stop taking temporarily when they require treatment with Zyvox. Additionally the Food and Drug Administration noted that Prozac (fluoxetine) should be withdrawn five weeks before using linezolid or methylene blue because of its unusually long half-life.

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. Confusion, memory issues, hyperactivity, excessive sweating, muscle twitching, shivering or shaking, diarrhea, trouble with coordination, and/or fever are among the symptoms of excess serotonin levels. 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.

In general, drugs with MAOI properties should not be given with antidepressants because of the danger of serotonin syndrome. However, healthcare professionals may not be aware that linezolid and methylene blue are in this class, but patients taking psychiatric drugs should not stop using them without first consulting a health-care professional. Treatment with serotonergic drugs can resume the day after the last dose of linezolid or methylene blue, the agency said.