XenoPort Announces Inclusion of HORIZANT (gabapentin enacarbil) in the WED Foundation Revised Consensus Statement on the

  XenoPort Announces Inclusion of HORIZANT (gabapentin enacarbil) in the WED
  Foundation Revised Consensus Statement on the Management of RLS/WED

Business Wire

SANTA CLARA, Calif. -- September 11, 2013

XenoPort, Inc. (Nasdaq: XNPT) announced today the inclusion of gabapentin
enacarbil, the active ingredient in HORIZANT^® (gabapentin enacarbil)
Extended-Release Tablets, as an initial therapy for chronic persistent
restless legs syndrome/Willis-Ekbom disease (RLS/WED) in an updated treatment
algorithm for patients with RLS/WED. The WED Foundation’s algorithm, published
in the current issue of Mayo Clinic Proceedings, provides information for
physicians determining treatment choices for RLS/WED based on disease
severity, existing comorbidities and the long-term benefits and risks of each
major class of medications.

The algorithm, first published in 2004, was updated to accommodate several
changes in the RLS/WED treatment landscape, including additional knowledge of
treatment with nonergot dopamine agonists, increased experience with calcium
channel alpha-2-delta ligands and the fact that several long-acting drugs have
become available. According to the revised algorithm, either non-ergot
dopamine agonists or the calcium channel alpha-2-delta ligands are recommended
as initial treatment for patients with chronic persistent RLS/WED, and the
choice of the initial treatment should be based on the individual clinical
features of RLS/WED in a given patient.

“This is the second publication of clinical guidance in two months that
addresses treatment and disease management considerations for RLS/WED,
indicating the urgency with which the neuroscience and broader physician
communities are seeking to better treat this condition,” said Mark Buchfuhrer,
M.D., Medical Director of the Southern California Restless Legs Syndrome
Support Group, attending physician at Downey Regional Medical Center in
Downey, Calif., and member of the WED Foundation’s Medical Advisory Board and
the International RLS Study Group. “This algorithm reflects evidence-based
assessments and expert opinion from practical experience, and hopefully will
serve as a much needed tool for physicians treating the estimated five million
moderate-to-severe RLS/WED patients nationwide.”

“Gabapentin enacarbil is the only non-dopamine agonist and member of the
calcium channel alpha-2-delta-ligand class that is approved by the FDA for the
treatment of moderate-to-severe primary RLS. We are excited that the updated
algorithm recognizes gabapentin enacarbil as an appropriate initial treatment
option for patients with chronic persistent RLS/WED,” stated Ronald W.
Barrett, Ph.D., chief executive officer of XenoPort, Inc. “XenoPort recognizes
that many RLS/WED patients have their disease for life and is committed to
understanding the long-term needs of these patients.”

About HORIZANT (gabapentin enacarbil) Extended-Release Tablets

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 the only non-dopamine agonist and calcium channel
alpha-2-delta-ligand approved by the U.S. Food and Drug Administration (FDA)
for the treatment of moderate-to-severe primary RLS in adults. (HORIZANT is
not interchangeable with other gabapentin products).

About Restless Legs Syndrome/Willis-Ekbom Disease

RLS/WED is a common disorder, occurring at least twice a week and causing at
least moderate distress in approximately 2 to 3% of the population. It is a
neurological condition that causes an irresistible urge to move the legs. This
urge is usually caused or accompanied by unpleasant sensations of burning,
creeping, tugging or tingling inside the patients’ legs, ranging in severity
from uncomfortable to painful. 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 such as walking or
massaging the legs. Symptoms often worsen at night, and disturbed sleep is a
common result of RLS. Left untreated, moderate-to-severe primary RLS may cause
exhaustion, daytime fatigue, inability to concentrate and impaired memory.

IMPORTANT SAFETY INFORMATION

Effects on Driving

HORIZANT may cause significant driving impairment. Patients should not drive
until they have enough experience on HORIZANT to know if it impairs their
driving. Patients’ ability to assess their driving competence and degree of
somnolence caused by HORIZANT can be imperfect.

Somnolence/Sedation and Dizziness

HORIZANT causes somnolence/sedation and dizziness. Patients should not drive
or operate other complex machinery until they have enough experience on
HORIZANT to know if it impairs their ability to perform these tasks.

Lack of Interchangeability with Gabapentin

HORIZANT is not interchangeable with other gabapentin products because of
differing pharmacokinetic profiles. The same dose of HORIZANT results in
different plasma concentrations of gabapentin relative to other gabapentin
products. The safety and effectiveness of HORIZANT in patients with epilepsy
have not been studied.

Suicidal Behavior and Ideation

HORIZANT is a prodrug of gabapentin, an antiepileptic drug (AED). AEDs
increase the risk of suicidal thoughts or behavior in patients taking these
drugs for any indication. As a prodrug of gabapentin, HORIZANT also increases
this risk. Patients treated with any AED for any indication should be
monitored for new or worsening depression, suicidal thoughts or behavior,
and/or any unusual changes in mood or behavior. Anyone considering prescribing
HORIZANT must balance the risk of suicidal thoughts or behavior with the risk
of untreated illness.

Patients, caregivers, and families should be informed that HORIZANT increases
the risk of suicidal thoughts and behavior and should be advised of the need
to be alert for new or worsening signs of and symptoms of depression, any
unusual changes in mood or behavior, or the emergence of suicidal thoughts,
behavior, or thoughts of self-harm. Behaviors of concern should be reported
immediately to healthcare providers.

Drug Reaction With Eosinophilia and Systemic Symptoms (DRESS)/Multiorgan
Hypersensitivity

Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS), also known as
multiorgan hypersensitivity, has been reported in patients taking
antiepileptic drugs, including gabapentin. HORIZANT is a prodrug of
gabapentin. Some of these events have been fatal or life-threatening. DRESS
typically, although not exclusively, presents with fever, rash, and/or
lymphadenopathy, in association with other organ system involvement, such as
hepatitis, nephritis, hematological abnormalities, myocarditis, or myositis
sometimes resembling an acute viral infection. Eosinophilia is often present.
Because this disorder is variable in its expression, other organ systems not
noted here may be involved.

It is important to note that early manifestations of hypersensitivity, such as
fever or lymphadenopathy, may be present even though rash is not evident. If
such signs or symptoms are present, the patient should be evaluated
immediately. HORIZANT should be discontinued if an alternative etiology for
the signs or symptoms cannot be established.

Discontinuation of HORIZANT

When discontinuing HORIZANT, patients with RLS receiving 600 mg or less once
daily can discontinue the drug without tapering. If the recommended dose is
exceeded, the dose should be reduced to 600 mg daily for 1 week prior to
discontinuation to minimize the potential of withdrawal seizure.

Tumorigenic Potential

In an oral carcinogenicity study, gabapentin enacarbil increased the incidence
of pancreatic acinar cell adenoma and carcinoma in male and female rats. The
clinical significance of this finding is unknown.

ADVERSE REACTIONS

The most common adverse reactions for patients with RLS receiving HORIZANT 600
mg, 1,200 mg, and placebo, respectively, were somnolence/sedation (20%, 27%,
and 6%), dizziness (13%, 22%, and 4%), headache (12%, 15%, and 11%), nausea
(6%, 7%, and 5%), and fatigue (6%, 7%, and 4%). A daily dose of 1,200 mg
provided no additional benefit compared with the 600-mg dose, but caused an
increase in adverse reactions.

DRUG INTERACTIONS

Gabapentin enacarbil is released faster from HORIZANT Extended-Release tablets
in the presence of alcohol. Consumption of alcohol is not recommended when
taking HORIZANT. HORIZANT taken in conjunction with morphine causes increased
somnolence/sedation, dizziness, and nausea.

USE IN SPECIAL POPULATIONS

Pregnancy and Lactation

Based on animal data, HORIZANT may cause fetal harm. There are no adequate and
well-controlled studies of HORIZANT in pregnant women. HORIZANT should be used
during pregnancy only if potential benefit justifies potential risk to fetus.
HORIZANT is converted to gabapentin, which is secreted into human milk.
Discontinue nursing or discontinue HORIZANT, taking into account the
importance of HORIZANT to the mother, due to potential for adverse reactions
in nursing infants.

Renal Impairment

In patients with RLS who have compromised renal function, HORIZANT should be
dosed based upon creatinine clearance (CrCl): 30 to 59 mL/min, start with 300
mg per day and increase to 600 mg as needed; 15 to 29 mL/min, use 300 mg per
day; <15 mL/min, use 300 mg every other day. HORIZANT is not recommended for
use in patients receiving hemodialysis.

For HORIZANT Prescribing Information/Medical Guide, please see the following
Websites:
http://www.HORIZANT.com/docs/HORIZANT_PrescribingInformation.pdf
http://www.HORIZANT.com/docs/HORIZANT_MedGuide.pdf

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. XenoPort is currently
commercializing HORIZANT in the United States and developing its novel fumaric
acid ester product candidate, XP23829, as a potential treatment for
relapsing-remitting multiple sclerosis and/or psoriasis. REGNITE^® (gabapentin
enacarbil) Extended-Release Tablets is being marketed in Japan by Astellas
Pharma Inc. XenoPort's pipeline of product candidates also includes potential
treatments for patients with spasticity related to spinal cord injury and
Parkinson's disease.

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

Forward-Looking Statements

This press release contains “forward-looking” statements, including, without
limitation, all statements related to HORIZANT as a potential initial
treatment option for patients with chronic persistent RLS/WED, future
treatment decisions involving the potential use of HORIZANT and any further
development plans of XenoPort. 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 “may,” “potential,” “should,” “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, XenoPort’s lack of
commercialization experience and its ability to  successfully market and sell
HORIZANT, including its ability to obtain appropriate pricing and
reimbursement for HORIZANT  in an increasingly challenging environment;
XenoPort’s ability to comply with applicable regulatory guidelines and
requirements with respect to the marketing and manufacturing of HORIZANT  or
with HORIZANT  post-marketing commitments or requirements mandated by the FDA;
and the uncertain therapeutic and commercial value of XenoPort’s product
candidates. 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
June 30, 2013, filed with the Securities and Exchange Commission on August 7,
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, Transported Prodrug and XENOPORT are trademarks of
XenoPort, Inc.

XNPT2G

Contact:

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