Sumatriptan transdermal iontophoretic patch (NP101-Zelrix (TM)): review of pharmacology, clinical efficacy, and safety in the acute treatment of migraine

Migraine is a chronic, painful, and often disabling primary headache disorder, typically presenting with recurrent attacks that may be accompanied by a variety of neurological, gastrointestinal, and autonomic symptoms. Gastrointestinal symptoms in association with migraine including, nausea, vomiting, and gastroparesis, affect a large proportion of migraine sufferers. These symptoms may result in delays or inconsistencies in the absorption of oral treatments. Hence, the necessity for an innovative, non-invasive, parenteral delivery formulation for quick and effective treatment of migraine attacks is evident. Iontophoresis utilizes minimal amounts of electrical potential to support the fast transfer of ionized medication transdermally and into the general circulation. Two pharmacokinetic clinical trials have shown that iontophoretic delivery of sumatriptan through the skin produces quick and reproducible therapeutic plasma concentrations. A randomized, double-blind, multicenter, phase III study demonstrated superior efficacy versus placebo and excellent tolerability, with no triptan-related adverse events. The proportion of patients that were pain-free at 2 h post-treatment was 18% for the sumatriptan patch vs 9% for placebo (P = 0.0092; number needed to treat = 11.1). Upon approval from the Food and Drug Administration and other regulatory authorities, the iontophoretic transdermal delivery of sumatriptan will be a good choice for patients experiencing poor absorption of oral medication often associated with migraine and/or for those with intolerable triptan-related adverse events.