Fixed drug eruption due to etoricoxib in a patient with tolerance to celecoxib: the value of patch testing.

Etoricoxib is a nonsteroidal anti-inflammatory drug (NSAID) that inhibits cyclooxygenase 2 (cox-2); it was introduced recently onto the market and is used widely. It has been implicated in several skin reactions and has been described as an uncommon cause of fixed drug eruption. We present a new case confirmed by patch testing. The patient was a 32-year-old woman with no relevant history of allergy. She came to our outpatients for evaluation of a pruritic and painful erythematous plaque measuring 1.5 cm on the cubital border of the left hand. The lesion had resolved leaving slight residual pigmentation. She reported 2 similar episodes that had occurred at the same site over the previous 3 months. The patient had taken various analgesics for episodes of pain secondary to a disc hernia. Those drugs had been ibuprofen, which she had taken again with no problem after the most recent skin reaction, and etoricoxib, which she had started to take 3 months earlier. Two months after the final episode, patch tests were performed on normal skin using the standard series of the Spanish Contact Dermatitis and Skin Allergy Research Group (GEIDAC), and an NSAID series (Marti Tor) that included celecoxib and etoricoxib (both at 10% in petrolatum). The results were negative. In addition, patches of 10% etoricoxib were applied to the site of the skin lesion, giving a positive result (++) at 48 and 96 hours (Fig. 1). A celecoxib patch was then applied to the previously damaged skin, with negative results, and controlled oral challenge with celecoxib was performed without observing any adverse reaction during the test or afterwards when taken regularly at the usual doses. Etoricoxib combines a potent anti-inflammatory activity with a good safety profile. As with other drugs of the same family, such as celecoxib, it has been implicated in various skin reactions, although with a much lower frequency. There are reports of cases of urticaria and angioedema, generalized exanthematous pustulosis, exudative erythema multiforme, toxic epidermal necrolysis, and fixed drug eruption. Fixed drug eruption is an uncommon skin reaction in which numerous drugs have been implicated, the NSAIDS being among the most common. Fixed reactions to the NSAIDs that inhibit cox-2 have been reported since their development but, in the case of etoricoxib, only 6 cases have been published. Diagnosis is based on the medical history and the characteristic skin lesions: 1 or several well-defined erythematous lesions, occasionally affecting mucosas, that