Celecoxib and Sulfa Drug Allergy

OB/GYN News, Nov 15, 2000 by Sally Koch Kubetin

Celecoxib is technically a sulfonamide, but it should not be automatically contraindicated in patients with a history of allergy to sulfa drugs, Dr. Neil H. Shear said at the American Academy of Dermatology's Academy 2000.

The sulfonamide antibiotics, which cause the overwhelming majority of severe sulfa drug reactions, contain an aromatic amine in their chemical structures.

This aromatic amine, when metabolized, can produce severe immunologic reactions in some individuals who are unable to detoxify the toxic metabolites, said Dr. Shear of the University of Toronto.

Celecoxib (Celebrex) does not contain an aromatic amine, and Dr. Shear maintains that it is highly unlikely to induce a Stevens-Johnson syndrome / toxic epidermal necrolysis (SJS/TEN) reaction, even in those with a history of reacting to sulfonamide antibiotics.

From January to June 1999, the first 6 months that celecoxib was on the market, approximately 7 million prescriptions for the drug were written.

"I found two possible cases of SJS/TEN," Dr. Shear said.

Based on the incidence of SJS/TEN associated with sulfamethoxazole, Dr. Shear said that out of 7 million prescriptions, one would expect between 30 and 70 SJS/TEN cases, 1,500-2,000 hypersensitivity syndrome episodes, and 20-30 deaths. The actual data show only one possible case of SJS/TEN and no episodes of hypersensitivity syndrome.