ARYx Therapeutics Inc. Updates Progress with Tecarfarin EmbraceAC Study

Phase 2/3 Clinical Trial Results To Be Released the Week of 6th July
FREMONT, Calif.--(Business Wire)--
ARYx Therapeutics Inc. (NASDAQ:ARYX), a biopharmaceutical company, announced
today that the database for the EmbraceAC study has been locked and the study
remains on schedule, with the efficacy and safety results to be available during
the week of July 6, 2009. The study was designed to compare its oral
anticoagulation therapy, tecarfarin (previously ATI-5923), against the leading
anticoagulant agent, warfarin. The purpose of the trial is to evaluate whether
tecarfarin is superior to warfarin in its ability to maintain patients within a
target therapeutic range of the level of anticoagulation as measured by INR
(International Normalized Ratio). Based upon recent interactions with the U. S.
Food and Drug Administration (FDA), ARYx believes this trial could be positioned
as one of the required registration studies for tecarfarin.

The raw data, containing both the efficacy and safety results, will now be
transferred to independent statisticians who will create the tables and listings
according to the previously adopted statistical analysis plan. This plan has
been reviewed by the FDA. The results from the study will remain blinded to ARYx
until just prior to their public release.

The trial of approximately 600 patients is a randomized, double blind, parallel
group, active control study comparing tecarfarin with warfarin in patients who
require chronic, oral anticoagulation. All patients in the study were treated
for a minimum of six months and required anticoagulation therapy to avoid
serious blood clotting resulting from their underlying condition. This includes
patients with atrial fibrillation; an implanted prosthetic heart valve; a
history of venous thromboembolic disease; a history of myocardial infarction or
cardiomyopathy; or another indication for which they are currently receiving
chronic warfarin therapy. The same target therapeutic range of INR has been
applied for patients receiving warfarin therapy as those administered
tecarfarin. The primary endpoint of the trial is to demonstrate that patients
are maintained within the target INR range a higher percentage of the time when
treated with tecarfarin than with warfarin.

For more information, go to http://www.clinicaltrials.gov/ct2/show/NCT00691470.

About Tecarfarin

Tecarfarin (previously ATI-5923) is modeled on the drug warfarin as an oral
anticoagulation therapy for patients who are in danger of forming
life-threatening blood clots as a result of atrial fibrillation, prosthetic
heart valve replacement or venous thromboembolism. There are at least an
estimated 3.5 million patients requiring anticoagulation therapy in the United
States alone. Patients with implanted mechanical heart valves are also amongst
those requiring anticoagulation therapy. Tecarfarin, like warfarin, is a
selective inhibitor of VKOR, or vitamin K epoxide reductase enzyme, and has the
same mechanism of anticoagulation action as warfarin. Unlike warfarin, which is
dependent upon cytochrome P450 enzymes for metabolism, tecarfarin was designed
to avoid drug-drug interactions through its alternative metabolic pathway. ARYx
believes the avoidance of cytochrome P450 metabolism will cause the dosing and
response to tecarfarin to be more predictable than with warfarin, avoiding the
dangers of over-or-under therapeutic anticoagulation long associated with that
therapy.

About ARYx Therapeutics, Inc.

ARYx Therapeutics is a biopharmaceutical company focused on developing a
portfolio of internally discovered products designed to eliminate known safety
issues associated with well-established, commercially successful drugs. ARYx
uses its RetroMetabolic Drug Design technology to design structurally unique
molecules that retain the efficacy of these original drugs but are metabolized
through a potentially safer pathway to avoid specific adverse side effects
associated with these compounds. ARYx currently has four products in clinical
development: an oral anticoagulant agent for patients at risk for the formation
of dangerous blood clots, tecarfarin (previously ATI-5923); an oral
anti-arrhythmic agent for the treatment of atrial fibrillation, budiodarone
(previously ATI-2042); a prokinetic agent for the treatment of various
gastrointestinal disorders, ATI-7505; and, an agent for the treatment of
schizophrenia and other psychiatric disorders, ATI-9242. Please visit the ARYx
Website at www.aryx.com for additional information.

Forward-looking Statements

This press release contains forward-looking statements, including, without
limitation, statements related to the potential safety and efficacy and further
development of tecarfarin, the timing and availability of our clinical results,
the initiation of new clinical trials, the ability of a product candidate to be
more predictable than currently available therapies regarding dosing and
response to treatment, and the ability of a product candidate to avoid the
dangers existing in currently available therapies. Words such as "believes,"
"estimates," "will," and similar expressions are intended to identify
forward-looking statements. These forward-looking statements are based upon our
current expectations. Forward-looking statements involve risks and
uncertainties. ARYx`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 risk
that our product candidates may not demonstrate safety and efficacy or lead to
regulatory approval, the risk that we may be unable to raise additional capital
when needed which would force us to delay, reduce or eliminate product
development programs, the risk that any failure or delay in commencing or
completing clinical trials for our product candidates could severely harm our
business, the risk that third party manufacturers could delay or prevent the
clinical development of our product candidates, risk that potential
collaborative arrangements will likely place the development of our product
candidates outside of our control, the risk that we may have to alter our
development and commercialization plans if collaborative relationships are not
established for tecarfarin, budiodarone and ATI-7505, the risk that our product
candidates may not demonstrate safety and efficacy or lead to regulatory
approval, the risk that we may be unable to raise additional capital when needed
which would force us to delay, reduce or eliminate product development programs,
the risk that any failure or delay in commencing or completing clinical trials
for our product candidates could severely harm our business, and the risk that
third party manufacturers could delay or prevent the clinical development of our
product candidates. These and other risk factors are discussed under "Risk
Factors" and elsewhere in our Annual Report on Form 10-K for the year ended
December 31, 2008, in our Quarterly Report on Form 10-Q for the quarter ended
March 31, 2009 and our other filings with the U.S. Securities and Exchange
Commission. ARYx expressly disclaims any obligation or undertaking to release
publicly any updates or revisions to any forward-looking statements contained
herein.

ARYx Therapeutics, Inc.
David Nagler, 510-585-2200 ext. 211
Vice President Corporate Affairs
dnagler@aryx.com

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