Valdecoxib ( Bextra ), a selective inhibitor of cyclo-oxygenase 2 ( COX-2 ), is indicated for the treatment of acute and chronic signs and symptoms of adult rheumatoid arthritis and osteoarthritis, for the relief of pain associated with primary dysmenorrhea.

Severe cutaneous adverse reactions (ARs) associated with Valdecoxib, including erythema multiforme (EM), Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN), have been reported internationally.

Health Canada received 9 Canadian reports of suspected cutaneous ARs associated with valdecoxib from the date of marketing, December, 2002, to August, 2003. Five cases were labelled serious; however, none of the patients had EM, SJS or TEN. There were no reported deaths. Two of the 5 serious reports indicated a history of allergy to sulfonamides. Given the seriousness of SJS and TEN, physicians should not prescribe Valdecoxib to patients with any previous allergic reactions to sulfonamides and should exert caution when prescribing it to patients prone to multiple drug allergies.

In a published case report, a patient with a previous allergy to an antimicrobial sulfonamide was diagnosed with TEN after treatment with Valdecoxib. Controversy exists regarding the potential for cross-reactivity between sulfonamide antimicrobials and other sulfonamide-containing compounds.
A recent study reported that cross-reactivity between antimicrobial sulfonamides and celecoxib appears to be low.
Another study suggests that a predisposition to allergic reactions, rather than a crossreactivity with sulfonamide-based drugs, is possible.

Health Canada has received reports of serious cutaneous reactions associated with Celecoxib and Rofecoxib in patients with and without a history of sulfa allergy.
Valdecoxib and Celecoxib have similar structures: both contain a benzenesulfonamide moiety.
The structure of Rofecoxib contains a methylsulfonyl moiety.

At least 50% of patients with SJS and TEN experience a 1- to 14-day prodrome of flu-like symptoms, including fever, malaise, rhinitis, chest pain, vomiting, sore throat, cough, diarrhea, headache,myalgia and arthralgia.
The progression from rash to desquamation can occur within a few days, or hours, and may result in fatal complications, such as infection and renal or respiratory failure.
It has previously been shown that early discontinuation of drugs with halflives of less than 24 hours may decrease the rate of death from TEN and SJS.
Because Valdecoxib has a half-life of about 8 hours, withdrawal of this drug when flu-like symptoms develop may decrease the risk of TEN and SJS in certain patients.

Therefore, health care professionals should encourage patients taking Valdecoxib to seek medical attention if any cutaneous or flu-like symptoms occur.

Source : Health Canada, 2004

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