XenoPort Provides Update on Availability of Horizant

Anticipates Product in Pharmacies in Early June

SANTA CLARA, Calif.--()--XenoPort, Inc. (Nasdaq: XNPT) announced today that shipments of Horizant® (gabapentin enacarbil) Extended-Release Tablets to its distributor in the United States have commenced. Depending on individual pharmacy ordering patterns, the product is anticipated to be generally available to patients in the first week of June.

“We are pleased that the issues related to manufacturing have been resolved and that product has now been shipped to our distribution center, which will be filling orders from wholesalers shortly,” commented Ronald W. Barrett, Ph.D., chief executive officer of XenoPort. “We have received inquiries from patients and physicians about the status of Horizant, hence our desire to make today’s announcement.”

On May 1, 2013, XenoPort re-acquired from GlaxoSmithKline (GSK) all commercialization rights to Horizant. Prior to the reacquisition of Horizant, GSK experienced manufacturing issues and delays that have resulted in a stockout of the product.

About Horizant (gabapentin enacarbil)

Gabapentin enacarbil is a patented molecule that was discovered and developed by XenoPort. It utilizes XenoPort’s Transported Prodrug technology that was designed to take advantage of high-capacity transport mechanisms in the gastrointestinal tract to offer efficient absorption and extended exposure of gabapentin. (Horizant is not interchangeable with other gabapentin products.)

About XenoPort

XenoPort, Inc. is a biopharmaceutical company focused on developing and commercializing a portfolio of internally discovered product candidates for the potential treatment of neurological disorders. Horizant, XenoPort’s internally discovered drug, is approved and being marketed by XenoPort in the United States. Regnite® (gabapentin enacarbil) Extended-Release Tablets is approved and is being marketed in Japan. Astellas Pharma Inc. holds all development and commercialization rights for Regnite in Japan and five other Asian countries. XenoPort holds all other world-wide rights to gabapentin enacarbil. XenoPort's pipeline of product candidates includes potential treatments for patients with spasticity, Parkinson's disease, relapsing-remitting multiple sclerosis and psoriasis.

Forward-Looking Statements

This press release contains “forward-looking” statements, including, without limitation, all statements related to the availability of Horizant to patients 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,” “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 XenoPort’s lack of commercialization experience and its ability to establish, or contract with third parties to establish, distribution, manufacturing, supply chain and other sufficient capabilities to manufacture and distribute Horizant and XenoPort’s ability to obtain uninterrupted drug supply. 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, 2013, filed with the Securities and Exchange Commission on April 24, 2013. 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.

Horizant, Regnite and XENOPORT are registered trademarks of XenoPort, Inc.

XNPT2G

Contacts

XenoPort, Inc.
Jackie Cossmon, 408-616-7220
ir@XenoPort.com

Contacts

XenoPort, Inc.
Jackie Cossmon, 408-616-7220
ir@XenoPort.com