Topical ketoconazole does not potentiate oral cyclosporin A in allergic contact dermatitis

Cyclosporin A is an effective drug but its use is limited by its side effects. Since oral ketoconazole inhibits the metabolism of oral cyclosporin, we set out to find out whether topical ketoconazole would enhance the effect in the skin of oral cyclosporin. Five patients with contact allergic dermatitis (CAD) were given a 6-day course of cyclosporin (1 mg/kg/day) and applied 2% ketoconazole cream to an area on one arm and the inert base to the other. Serial dilutions of the relevant allergen were applied to the arms at 3 days for 48 hours, and the responses were measured objectively a day later. There was no significant difference between responses at the two sites, indicating that topical ketoconazole does not enable the dose of oral cyclosporin to be reduced in CAD.