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hsavelle@dynogen.com dmacdougall@macbiocom.com DYNOGEN ANNOUNCES POSITIVE RESULTS IN PHASE 2 IBS-D STUDY
- DDP225 Results Mark Dynogen’s Third Set of Positive Proof of Concept Data This Year -
WALTHAM, Mass., December 17, 2007 – Dynogen Pharmaceuticals, Inc. today announced positive
results from its Phase 2 trial of DDP225 in patients with irritable bowel syndrome with diarrhea (IBS-d).
The randomized, double-blind, placebo controlled trial generated statistically significant results for the
clinical endpoint of relief from abdominal pain or discomfort associated with IBS-d. Detailed results
will be submitted for disclosure in a peer-reviewed journal or at a future medical conference.
The 1 mg dose of DDP225 administered once daily for eight weeks achieved a 71% response rate
compared to a 25% response rate for placebo in the prospectively defined clinical endpoint of adequate
relief of IBS pain or discomfort. This was a statistically significant (p=0.009) benefit over placebo using
an efficacy measure accepted by the FDA as the basis for approval for treatment of IBS-d. Dynogen’s
Phase 2 trial enrolled 87 women at multiple centers in the U.S. and Canada. DDP225 was safe and well
tolerated in this study.
“The high response rate together with the 46% separation from placebo seen in this Phase 2 study
demonstrates compelling proof of concept for DDP225 as a treatment for IBS-d,” commented Dr. Suhail
Nurbhai, MRCP, Vice President of Clinical Development at Dynogen. “IBS-d is a painful and
debilitating condition for which current therapy is extremely limited, and we look forward to initiating a
Phase 2b trial of DDP225 in 2008.”
“The DDP225 results mark the third set of positive proof of concept data to come from Dynogen’s
clinical development pipeline within the last year and position us as the only company with advanced
stage programs in both IBS-c and IBS-d,” said Dr. Lee R. Brettman, M.D., Dynogen’s President and
Chief Executive Officer. “We are on track to have four Phase 3-ready programs within the next 24
months, based on these data and positive results in our planned trials.”

About DDP225
DDP225 is an oral noradrenaline reuptake inhibitor (NARI) and a weak 5HT3 receptor antagonist that
Dynogen is developing for IBS-d. Noradrenaline and serotonin are neurotransmitters that are known to
be involved in the control of the gastrointestinal system. The unique combination of noradrenaline
reuptake inhibition and weak 5HT3 antagonism in one orally delivered compound represents a novel
approach to treating IBS-d, enabling efficacy to be achieved at very low and well tolerated doses of
DDP225. Dynogen licensed preclinical and clinical data related to DDP225 from Mitsubishi Tanabe
Pharma in October 2003. It has been dosed to over 450 human subjects for durations up to 12 weeks,
and at single doses up to 100 mg. Dynogen owns issued patents and pending patent applications related
to the use of DDP225 as a treatment for IBS.
About Irritable Bowel Syndrome (IBS)
IBS affects approximately 12% of the U.S. population, or 27 million patients. IBS is a chronic disease
characterized by abdominal pain and discomfort associated with altered bowel habit. IBS is associated
with $1.6 billion in direct medical costs and $19.2 in indirect costs in the U.S. each year. Patients with
IBS make an average of 5.5 visits to the physician each year compared to 1.9 visits annually for people
without bowel symptoms. Additionally, people with IBS incur healthcare costs nearly 50% higher than
the average American, and miss three times as many day of work. Zelnorm® (tegaserod, Novartis) was
the only approved drug for IBS with constipation (IBS-c) and was suspended from marketing by the
FDA in March 2007, except in rare and restrictive cases. Lotronex® (alosetron, GSK) is the only drug
approved by the FDA for the treatment of IBS-d, but its use is restricted to women with severe disease
who have not responded adequately to other therapies and is subject to a comprehensive and restrictive
prescribing program.

About Dynogen Pharmaceuticals, Inc.
Dynogen is a clinical-stage company developing a portfolio of treatments for gastrointestinal and
genitourinary disorders. The Company is focused on large and underserved markets in disease areas that
severely impair a patient’s quality of life, such as irritable bowel syndrome, gastroesophageal reflux
disease and overactive bladder. The Company leverages its development expertise to identify promising
clinical compounds and rapidly advance them towards registration. www.dynogen.com

Source: http://numedicus.co.uk/files/DDP225_Phase_2a_Trial_Results_pr_171207.pdf