The inhibitory effects of topical chelating agents and antioxidants on nickel-induced hypersensitivity reactions.

Abstract

Nickel sensitivity is a common problem, often causing significant morbidity from chronic eczematous dermatitis. The main treatment, topical steroids, usually is unable to suppress the dermatitis completely. Our purpose was to study the effects of "barrier" ointments containing either chelating agents (clioquinol or ethylenediaminetetraacetic acid [EDTA]) or antioxidants (ascorbic acid or alpha-tocopherol) and 1% hydrocortisone on nickel-induced hypersensitivity reactions. Nickel-sensitive subjects were challenged with nickel-containing coins coated with the desired barrier ointment and their inhibitory effects observed. Patients with bilateral hand or earring dermatitis explored the efficacy of these agents in clinical use. Clioquinol (3%) completely abolished the allergic reaction in all 29 subjects tested. EDTA (15%), ascorbic acid (20%), and alpha-tocopherol (10%) were less effective, and 1% hydrocortisone had no significant effect. In clinical use sites treated with a commercially available preparation containing 3% clioquinol and 1% hydrocortisone showed marked clinical improvement in all 10 subjects. Clioquinol is a potent inhibitor of nickel-induced hypersensitivity reactions and is feasible to use as a barrier ointment to block the allergenic effects of nickel in sensitive patients.