Topical iontophoretic administration of acyclovir for the episodic treatment of herpes labialis: a randomized, double-blind, placebo-controlled, clinic-initiated trial.

Background: Multiple studies of the use of acyclovir for the treatment of herpes labialis have suggested that the nominal efficacy of the topical formulation is the result of inadequate penetration of the drug into the target site of infection, the basal epidermis.

Methods: We developed a low-voltage, wireless, hand-held, computer-controlled, iontophoretic applicator to enhance the skin penetration of topical acyclovir in the treatment of herpes labialis. We performed a multicenter, placebo-controlled, clinic-initiated, pilot trial of a single, topical, iontophoretic application of 5% acyclovir cream for the episodic treatment of herpes labialis among 200 patients with an incipient cold sore outbreak at the erythema or papular/edema lesion stage.