Gabapentin Enacarbil for Treatment of Restless Legs Syndrome in Adults

Abstract

To review the pharmacology, pharmacokinetics, clinical efficacy, adverse effects, drug interactions, precautions, dosing recommendations, and patient counseling for gabapentin enacarbil for the treatment of restless legs syndrome (RLS) in adults. A literature search was conducted using the terms gabapentin enacarbil, XP13512/GSK1838262, and restless legs syndrome. MEDLINE, Books@Ovid, Journals@Ovid Full Text, BIOSIS Previews, and EMED databases were the primary search sites (2004-October 2011). All English-based articles and abstracts obtained from the literature searches were reviewed. Additional information was obtained from references cited in the articles. All gabapentin enacarbil information related to RLS was considered. Study selection included human trials evaluating safety and efficacy of gabapentin enacarbil for the treatment of RLS. Gabapentin enacarbil is a prodrug of gabapentin that is Food and Drug Administration (FDA) approved for the treatment of moderate-to-severe primary RLS in adults. In placebo-controlled trials, gabapentin enacarbil demonstrated efficacy in reducing the symptoms of RLS. Most clinical trials assessed gabapentin enacarbil at dosages greater than the FDA-approved 600-mg dosage. For the approved dose of 600 mg, the most commonly reported adverse effects are somnolence and dizziness. Clinical trials have evaluated gabapentin enacarbil for safety and efficacy in treating moderate-to-severe RLS symptoms for up to 64 weeks. It offers a pharmacokinetic advantage over gabapentin by having improved absorption and a longer duration of action, but clinically significant differences are yet to be determined. Potential disadvantages of gabapentin enacarbil include cost, concerns of suicide risk and pancreatic cancer, and a lack of data for the FDA-approved 600-mg dosage. Overall, gabapentin enacarbil is a viable therapeutic option for adults with moderate-to-severe RLS for whom more conventional therapies have failed.