FDA Sends Pfizer a Zithromax Warning Letter

New York, NYConcern about a lack of adequate warnings regarding Zithromax side effects has prompted the US Food and Drug Administration (FDA) to issue a warning letter to Pfizer. Among the concerns is whether or not the risk of Zithromax reactions, such as Zithromax SJS (Stevens Johnson Syndrome) is adequately represented on a brochure for the drug. Zithromax, often referred to as Zmax, Z-pack or azithromycin, has been linked to rare instances of Stevens Johnson Syndrome, a potentially fatal allergic reaction to medication.

The letter, dated June 19, 2012 (found online at www.fda.gov) takes issue with Pfizer's "1 Day. 1 Dose" brochure for Zmax (azthiromycin extended release) medication. "The brochure is false or misleading because it omits and minimizes important risk information, makes unsubstantiated superiority claims, omits material facts, broadens the indication for the drug product, makes misleading efficacy claims, and makes unsubstantiated claims for Zmax."

The FDA acknowledges that the drug's warning label discusses the risk of Stevens Johnson Syndrome, but argues that the brochure does not disclose the severity of the allergic reaction??"which is potentially fatal??"and further does not mention that some severe allergic symptoms recurred in patients even when they discontinued azithromycin. Furthermore, the FDA notes that the efficacy claims regarding Zmax are positioned prominently on the brochure, while the information about the risks is included without headers to alert the reader of its significance.

The FDA notes that failure to disclose the severity of the potentially fatal allergic reaction is misleading and downplays the risks associated with azithromycin.

The warning label for Zmax states, "Serious allergic reactions, including angioedema, anaphylaxis, Stevens Johnson syndrome and toxic epidermal necrolysis have been reported rarely in patients on azithromycin therapy using other formulations. Although rare, fatalities have been reported." It further notes that some patients have suffered recurrence of their symptoms despite having no further exposure to azithromycin.

Other concerns expressed by the FDA are a lack of warning about the risk of QT prolongation, unsubstantiated safety claims, broadening of the drug's indication and unsubstantiated superiority claims.

The FDA requested that Pfizer stop using the brochure in question and gave the drug company until July 3 to provide a written response to the FDA's warning letter.

Azithromycin is an antibiotic used to treat infections caused by bacteria. Stevens Johnson Syndrome is a potentially fatal allergic reaction to medication, in which the patient develops blistering and burn-like symptoms over her body and in her mucous membranes. Patients who survive Stevens Johnson Syndrome often have permanent damage including vision problems, scarring and loss of hair and nails.