Submission Based on Results from Pivotal Trials Evaluating Efficacy, Safety and Maintenance of Effect in Patients with Moderate-to-Severe Primary RLS

RESEARCH TRIANGLE PARK, N.C. and SANTA CLARA, Calif., Sept. 16 /PRNewswire-FirstCall/ -- GlaxoSmithKline (NYSE: GSK) and XenoPort, Inc. (Nasdaq: XNPT) announced today that a New Drug Application (NDA) has been submitted to the U.S. Food and Drug Administration (FDA) requesting approval of Solzira(TM) (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, M.D., senior vice president, GlaxoSmithKline Neurosciences Medicine Development Center. 'We believe that Solzira may offer a new therapeutic option to treat primary Restless Legs Syndrome, 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 (PIVOT RLS I and PIVOT RLS II), which evaluated the safety and efficacy of Solzira over 12 weeks. The submission also included results from a third pivotal trial (PIVOT RLS Maintenance) 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 program for Solzira,' said Ronald W. Barrett, Ph.D., chief executive officer of XenoPort.