GlaxoSmithKline (GSK) and XenoPort, Inc announced that a New Drug Application (NDA) has been submitted to the US Food and Drug Administration (FDA) requesting approval of Solzira (gabapentin enacarbil) extended release tablets for the treatment of moderate-to-severe primary restless legs syndrome (RLS). RLS affects an estimated 12 million people in the United States and can result in distressing symptoms that disrupt sleep and significantly impact daily activities.

Solzira is a non-dopaminergic new chemical entity that provides improvement in the symptoms of RLS with the convenience of a once-daily formulation.

"GSK is committed to bringing innovative products to patients where there is unmet medical need," said Atul Pande, senior vice president, GSK Neurosciences Medicine Development Center. "We believe that Solzira may offer a new therapeutic option to treat primary RLS, a condition that includes both sensory and motor symptoms."

The NDA submission is based on a comprehensive phase-3 clinical development program for Solzira in patients with moderate-to-severe primary RLS, including data from two randomized, double-blind, placebo-controlled trials, which evaluated the safety and efficacy of Solzira over 12 weeks. The submission also included results from a third pivotal trial evaluating the ability of Solzira to maintain efficacy in treating RLS symptoms over a nine-month period. The most common side effects of Solzira were dizziness and somnolence.

"We are very encouraged by the results that we have seen in the clinical development programme for Solzira," said Ronald W Barrett, chief executive officer of XenoPort. "Solzira is the first non-dopaminergic compound to demonstrate efficacy in large, controlled clinical trials for the treatment of primary RLS, and we believe it will offer patients a beneficial alternative to currently approved therapies."

Solzira is a new chemical entity that is designed to improve upon the pharmacokinetics of gabapentin by taking advantage of high-capacity transport mechanisms in the gastrointestinal tract to improve absorption.

XenoPort, Inc. is a biopharmaceutical company focused on developing a portfolio of internally discovered product candidates that utilize the body's natural nutrient transport mechanisms to improve the therapeutic benefits of existing drugs.