Allergenicity and tolerogenicity of amlexanox in the guinea pig

Amlexanox (AMLX), an anti-allergic agent, is available in Japan as Elics opthalmic solution, Solfa nasal douche and Solfa tablets. Cases of allergic contact dermatitis induced by Elics ophthalmic solution, which contains 0.25% AMLX, were reported within a year of its introduction. We therefore examined the contact sensitizing potency of AMLX. Guinea pigs sensitized to 0.25% AMLX exhibited a strong positive patch test reaction. Further, AMLX-sensitized animals developed rashes following oral and systemic challenge with AMLX. This animal model reflected the clinical experience of systemic contact dermatitis due to AMLX. The non-responsiveness induced by oral administration of AMLX to AMLX-induced animals was transient, and clinical prophylaxis by desensitization with oral AMLX may only increase the risk of systemic contact dermatitis. On the other hand, there have been few reports of drug eruption from oral Solfa tablets in spite of their wide use. Therefore, we also examined the induction of tolerance by oral administration of AMLX. Oral administration of AMLX before sensitization resulted in complete non-responsiveness. It seems likely that a substantial reduction in the risk of AMLX sensitization by Elics may be achieved by prior oral administration of Solfa tablets containing AMLX.