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Treatment for Restless Legs Syndrome, Postherpetic Neuralgia

Horizant (gabapentin enacarbil) Now Approved - April 6, 2011

XenoPort to Receive $23 Million in Milestone Payments Associated With FDA Acceptance of Solzira NDA

SANTA CLARA, Calif.--(BUSINESS WIRE)--Mar 16, 2009 - XenoPort, Inc. announced today that the U.S. Food and Drug Administration (FDA) has accepted for review the new drug application (NDA) filed by GlaxoSmithKline (GSK) for Solzira (gabapentin enacarbil) Extended Release Tablets in the United States as a potential treatment for moderate-to-severe primary Restless Legs Syndrome (RLS). In accordance with XenoPort's collaboration agreements with GSK and -Astellas Pharma Inc., the FDA's acceptance of the NDA triggers milestone payments to XenoPort of $23 million in the aggregate.

About Solzira

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.

About RLS

RLS is a common neurological condition that affects an estimated 12 million people in the United States across a range of severity from mild to severe. The syndrome is characterized by unpleasant and sometimes painful sensations in the legs that result in a compelling urge to move and can result in distressing symptoms that disrupt sleep and significantly impact daily activities. These RLS-related symptoms typically begin or worsen during periods of rest or inactivity, particularly when lying down or sitting, and may be temporarily relieved by movement.

About XenoPort

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. XenoPort is developing its lead product candidate in collaboration with Astellas and GSK. The FDA is currently reviewing the NDA filed by GSK for Solzira as a potential treatment for 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. 

Forward-Looking Statements

This press release contains “forward-looking” statements, including, without limitation, all statements related to XenoPort's and its partners' future clinical development of Solzira and the timing thereof; the therapeutic and commercial potential of XenoPort's product candidates; the regulatory process; and milestone payments and the timing thereof. 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 “anticipated,” “expected,” “potential,” “would” 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 uncertain results and timing of clinical trials; XenoPort's or its partners' ability to successfully conduct clinical trials in the anticipated timeframes, or at all; the uncertainty of the FDA's NDA approval process and other regulatory requirements; XenoPort's dependence on its current and additional collaborative partners; and the uncertain therapeutic and commercial value of XenoPort's and its licensees' compounds. These and other risk factors are discussed under the heading “Risk Factors” in XenoPort's Annual Report on Form 10-K filed with the Securities and Exchange Commission on February 26, 2009. 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.

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