Chronic desensitization to quinolones in fixed drug eruption.

Successful desensitization protocols have been reported in patients with fi xed drug eruption (FDE) [1-3]. In chronic diseases, it would be desirable to sustain the tolerance achieved after desensitization. Maintained tolerance has been reported in immunoglobulin (Ig) E–mediated hypersensitivity reactions [4,5], but not in FDE. We report the case of a 28-year-old female with cystic fi brosis who developed several erythematous plaques on both hands while being treated with ciprofl oxacin 10 years previously. In order to offer the patient an alternative drug, we performed a gradual dose challenge with levofl oxacin. Two hours after receiving the full dose (500 mg), the lesions reappeared at the same sites, confi rming the diagnosis of FDE and cross-reactivity between the 2 drugs. Ciprofl oxacin was the fi rst choice for her disease, so we proposed a slow desensitization regimen, as described elsewhere with cotrimoxazole in FDE [3]. She could not delay administration of ciprofl oxacin for long and agreed to receive progressive oral doses of ciprofl oxacin over a period of 3 days 4 months after the positive challenge test with levofl oxacin. On the second day, the lesions reappeared on her hands but she decided to continue with administration and received 750 mg twice daily until she completed a 21-day course. Her condition worsened initially, with intense itching and desquamation of the plaques. The lesions improved after 14 days and disappeared before concluding treatment with ciprofl oxacin. She was then treated with daily doses of pipemidic acid, a fi rst-generation quinolone. After 6 months of maintenance therapy with this agent, a new therapeutic course of ciprofl oxacin was administered. Mild nonpruritic lesions that vanished in only 24 hours without desquamation reappeared at the same sites. The patient has been receiving a twice-daily maintenance dose of 400 mg of pipemidic acid since then Ciprofl oxacin