Product Liability

FDA issues warning of serious adverse reaction to antidepressants

Several popular medications prescribed to treat depression, including Effexor, Paxil, and Prozac, have issued changes to the “Contradictions and Warnings” sections of their labels to warn of a potentially life-threatening adverse reaction known as Neuroleptic Malignant Syndrome (NMS).

NMS is a neurological disorder that presents with muscle rigidity, fever, autonomic instability and cognitive changes such as delirium and associated with elevated levels of the enzyme creatine phosphokinase. Once symptoms appear, the progression of the condition is rapid, reaching peak intensity in as little as three days. Symptoms can last anywhere from eight hours to 40 days. The symptoms of NMS sometimes are misinterpreted by doctors as symptoms of mental illness, which can delay treatment.

NMS is caused almost exclusively by the blocking of dopamine receptions with antipsychotic medications. The higher the dosage of the medicine, the more common the occurrence. It may also be caused by rapid and large doses of medication.

The labeling changes were issued by the Food and Drug Administration (FDA) in its January 2009 postings of 28 drug products with safety labeling changes on boxed warnings, contradictions, warnings, precautions, adverse reactions, patient package inserts and medication guides. The antipsychotic drugs that now carry the NMS warning include Celexa, Lexapro, Cymbalta, Effexor, Paxil, Pexeva, Pristiq, Prozac, Venlafaxine and Zoloft.

The FDA’s posting also includes a boxed warning on Cimzia, and adverse reactions, warnings and/or precautions for Avelox, Hycodan, Nicardipine Hydrochloride, Tygacil, Tyzeka.

For a full listing and the specific doses of antidepressants with revised “Contradictions and Warnings,” and other medications with labeling changes, check out the FDA’s MedWatch report.