Astellas and XenoPort Announce the Launch of Regnite® Tablets for Restless Legs Syndrome in Japan

<0> XenoPort, Inc.Jackie Cossmon, 408-616-7220 </0>

Astellas Pharma Inc. (Tokyo: 4503) and XenoPort, Inc. (NASDAQ: XNPT) announced today that Regnite (gabapentin enacarbil) Extended-Release Tablets will be launched in Japan on July 10, 2012. is approved in Japan for the treatment of moderate-to-severe primary restless legs syndrome (RLS). Astellas’ promotional efforts will focus on sleep and neurology specialists. Approximately 1,200 Astellas sales representatives will participate in the promotion of .

Discovered by XenoPort, is dosed once-daily and delivers a new chemical entity that utilizes naturally-occurring, high-capacity, nutrient transporters in the gastrointestinal tract to achieve efficient absorption into the body. Once absorbed, is rapidly converted into gabapentin, a compound thought to work by binding to certain calcium channels in nerve terminals. provides dose-proportional and extended exposure of gabapentin. The approved daily dose of for the treatment of RLS is 600 mg per day. The National Health Insurance (NHI) drug price per 300 mg tablet of is 98.50 yen.

was approved on January 18, 2012 by the Japanese Ministry of Health, Labour and Welfare for the treatment of RLS in Japan.

Restless legs syndrome is a neurological condition that 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 restless legs syndrome-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. It is estimated that there are approximately 2.1 million people in Japan with RLS.

In 2005, Astellas obtained exclusive rights to develop and commercialize in Japan, Korea, the Philippines, Indonesia, Thailand and Taiwan. XenoPort has received payments of $65 million to date under the collaboration agreement. XenoPort is eligible to receive potential additional clinical and regulatory milestone payments totaling up to $20 million. Under the agreement, XenoPort is also eligible to receive royalties on net sales of in the Astellas territory at a royalty rate in the high-teens on a percentage basis.

Astellas Pharma Inc., located in Tokyo, Japan, is a pharmaceutical company dedicated to improving the health of people around the world through the provision of innovative and reliable pharmaceutical products. Astellas has approximately 17,000 employees worldwide. The organization is committed to becoming a global category leader in Urology, Immunology (including Transplantation) and Infectious Diseases, Oncology, Neuroscience and DM Complications and Kidney Diseases. For more information on Astellas Pharma Inc., please visit the company Website at .

XenoPort is a biopharmaceutical company focused on developing and commercializing a portfolio of internally discovered product candidates for the potential treatment of neurological disorders. Horizant® (gabapentin enacarbil) Extended-Release Tablets is approved in the United States for the treatment of RLS in adults and for the management of postherpetic neuralgia in adults. GlaxoSmithKline holds commercialization rights and certain development rights for in the United States. XenoPort holds all other world-wide rights and has co-promotion and certain development rights to gabapentin enacarbil in the United States. XenoPort’s pipeline of product candidates includes potential treatments for patients with spasticity, Parkinson’s disease and relapsing-remitting multiple sclerosis.

To learn more about XenoPort, please visit the company Website at .

This press release contains “forward-looking” statements, including, without limitation, all statements related to Astellas’ commercialization and marketing of and the timing thereof; the therapeutic and commercial potential of ; and potential milestone payments and royalties 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 “estimated,” “potential,” “will” 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, risks related to Astellas’ ability to successfully commercialize and promote in Japan; XenoPort's dependence on its collaborative partners; and the uncertain therapeutic and commercial value of XenoPort'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 March 31, 2012, filed with the Securities and Exchange Commission on May 8, 2012. 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.

and are registered trademarks of XenoPort, Inc.

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