GSK and Xenoport resubmit new drug application for Solzira™ in restless legs syndrome

Issued:  Friday 9 January 2009, London, UK, Research Triangle Park, NC & Santa Clara, CA

GlaxoSmithKline and XenoPort, Inc. announced today that GSK has resubmitted the New Drug Application (NDA) to the U.S. 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). 

The FDA had requested that the data in a single study be reformatted. In addition, GSK conducted a review of other clinical studies taking this input into account. The withdrawal was not related to the content of the filing. 

GlaxoSmithKline – one of the world’s leading research-based pharmaceutical and healthcare companies – is committed to improving the quality of human life by enabling people to do more, feel better and live longer.  For further information please visit www.gsk.com

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 -  is a biopharmaceutical company focused on developing a portfolio of internally discovered product candidates that utilise the body’s natural nutrient transport mechanisms to improve the therapeutic benefits of existing drugs.  XenoPort is developing its lead product candidate in partnership with Astellas Pharma Inc. and GSK.  As announced today, GSK has resubmitted to the FDA an NDA for Solzira for the treatment of moderate-to-severe primary RLS.  XenoPort’s product candidates are also being studied for the potential treatment of gastroesophageal reflux disease, migraine headaches, neuropathic pain, spasticity related to spinal cord injury, acute back spasms and Parkinson’s disease.  To learn more about XenoPort, please visit the Web site at www.XenoPort.com.

XenoPort Enquiries:

GlaxoSmithKline cautionary statement regarding forward-looking statements
Under the safe harbor provisions of the U.S. Private Securities Litigation Reform Act of 1995, GSK cautions investors that any forward-looking statements or projections made by GSK, including those made in this announcement, are subject to risks and uncertainties that may cause actual results to differ materially from those projected. Factors that may affect GSK' s operations are described under 'Risk Factors' in the 'Business Review' in the company' s Annual Report on Form 20-F for 2007.

XenoPort Forward-Looking Statement

This press release contains "forward-looking" statements, including, without limitation, all statements related to the therapeutic and commercial potential of XenoPort’s product candidates. Any statements contained in this press release that are not statements of historical fact may be deemed to be forward-looking statements. Words such as "potential" and similar expressions are intended to identify forward-looking statements. These forward-looking statements are based upon XenoPort's current expectations. Forward-looking statements involve risks and uncertainties. XenoPort' s actual results and the timing of events could differ materially from those anticipated in such forward-looking statements as a result of these risks and uncertainties, which include, without limitation, the ability of the company to successfully conduct clinical trials of its product candidates, and the results thereof; the uncertainty of the FDA approval process and other regulatory requirements; XenoPort' s dependence on its current and additional collaborative partners; and the therapeutic and commercial value of the company' s compounds. These and other risk factors are discussed under the heading "Risk Factors " in XenoPort' s Quarterly Report on Form 10-Q for the quarter ended September 30, 2008, filed with the Securities and Exchange Commission on November 6, 2008. XenoPort expressly disclaims any obligation or undertaking to release publicly any updates or revisions to any forward-looking statements contained herein to reflect any change in the company's expectations with regard thereto or any change in events, conditions or circumstances on which any such statements are based.