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

ABSTRACT

BACKGROUND: 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. OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.