-Claims cover IBS-c and GERD –

WALTHAM, Mass., April 17, 2007 – Dynogen Pharmaceuticals, Inc. announced today that the European Patent Office has allowed two patent applications related to the uses of DDP733 (pumosetrag): the first for the treatment of irritable bowel syndrome with constipation (IBS-c) and the second for the treatment of gastroesophageal reflux disease (GERD). The claims of EP Application No. 02705169.7-1521 are directed to the use of DDP733 for the treatment and prevention of IBS-c, as well as for the treatment of abdominal pain and discomfort associated with IBS-c. The claims of the second allowed application, which issued as EP Patent No. 1256581 on March 28, 2007, are directed to the use of DDP733 for the treatment of GERD.

Dynogen currently has active clinical programs in both indications. In February of this year, Dynogen announced positive results from its Phase 2 study of DDP733 in IBS-c, with a statistically significant improvement over placebo in the Subject Global Assessment of IBS, an endpoint that has been accepted by the FDA as a registration endpoint for the indication. The Company is planning to initiate a Phase 2b study in IBS-c this year. Dynogen is also studying DDP733 in a Phase 1b translational medicine clinical trial designed to show a reduction in reflux episodes and demonstrate proof of concept for DDP733 as a treatment for nocturnal GERD. The Company expects to complete this trial in the first half of 2007.

“We are delighted to announce these important patent achievements on the heels of our positive Phase 2 data for DDP733 in IBS-c. The IBS-c and GERD patents will provide Dynogen with protection in Europe lasting at least until 2022 and 2021, respectively,” said Mark Boshar, Vice President, Legal Affairs and Chief Patent Counsel at Dynogen. “With our recent clinical achievement and our rapidly maturing patent portfolio, our DDP733 programs are well-positioned for success as we move into late-stage clinical trials and strategic partnering discussions.”

Dynogen’s DDP733 patent portfolio includes both composition of matter and method of use patents and applications exclusively licensed from Mitsubishi Pharma Corp. as well as patent applications owned exclusively by Dynogen.

“Our new European patents for DDP733 in IBS and GERD are very critical to the Company because of the enormous market opportunity that these indications possess,” said Lee R. Brettman, M.D., Chief Executive Officer at Dynogen. “IBS affects as many as 15% of the worldwide population while approximately 10% of the worldwide population suffers from GERD, with 80% of those reporting symptoms of nocturnal GERD. Currently, there are no effective therapies approved for the long-term treatment of either disorder. Based on our positive clinical and safety results and our compelling preclinical data, we believe that DDP733 could make a significant impact in both of these markets.”

About DDP733

DDP733 is an oral, partial agonist of the serotonin type 3 receptor (5-HT₃). Serotonin is a neurotransmitter that is known to be involved in the control of the gastrointestinal (GI) system. Preclinical studies of DDP733 established the compound’s prokinetic properties (the ability to promote the motility of the GI tract). Dynogen’s preclinical studies have also shown that DDP733 is minimally absorbed by the cells lining the gastrointestinal tract and, as a result, more of the product candidate remains available at the desired local site of action. A recently completed Phase 2 study of the candidate demonstrated an overall clinical response rate of 54% in patients receiving a dose of 1.4 mg t.i.d. compared to a 15% clinical response rate for patients receiving placebo, and the drug was also well-tolerated. Previous clinical studies of the compound have demonstrated favorable safety and pharmacokinetic profiles.

About Irritable Bowel Syndrome (IBS)

Irritable bowel syndrome is a chronic condition that is believed to be caused by the dysfunction of the muscles and/or nerves of the organs of the GI tract. Patients with IBS experience abdominal pain, discomfort and bloating accompanied by altered bowel habit that can include either diarrhea, constipation or both. IBS has prevalence of up to 12% of the general population, and females account for 80% of the patient population with severe cases. It is the most common disease diagnosed by gastroenterologists and one of the most common disorders seen by primary care physicians.

About Nocturnal Gastroesophageal Reflux Disease (NGERD)

Gastroesophageal reflux disease (GERD) is a chronic condition that afflicts over 20 percent of adults in the United States. Persistent heartburn is the most frequent symptom of GERD, but patients may also experience acid regurgitation into the esophagus, dyspepsia (stomach pain) and dysphagia (difficulty swallowing). GERD affects all age groups, although the incidence increases markedly after the age of 40. If left untreated, complications of GERD can include esophageal erosions or ulcers and abnormal narrowing of the esophagus. Years of chronic heartburn, left untreated, can lead to aggressive esophageal cancer, currently the fastest growing cancer in the United States. NGERD is the occurrence of GERD at night, typically while lying down to sleep. Symptoms associated with stomach reflux are exacerbated by the lack of assistance from gravity while lying recumbent. NGERD is commonly associated with a higher risk and a higher degree of esophagitis: acid remains in the esophagus for prolonged periods because there is less swallowing and less saliva produced to neutralize the acid. It is estimated that approximately one-third of patients suffering from GERD also suffer from NGERD.

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 untapped 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. Dynogen currently has multiple double-blind, placebo-controlled Phase 2 studies underway. www.dynogen.com