Axonyx Expands Ongoing Phenserine Clinical Program.

Business Editors/Health/Medical Writers

NEW YORK--(BUSINESS WIRE)--Sept. 18, 2003

Axonyx Inc. (NASDAQ:AXYX) today announced that it intends to provide Alzheimer's disease (AD) patients in the ongoing Phase IIB and Phase III clinical trials the opportunity to receive Phenserine treatment in a formal open label six-month extension study. Phenserine is a dual action acetylcholinesterase and beta amyloid precursor protein (B-APP) inhibitor currently in clinical development for the treatment of mild-to-moderate Alzheimer's disease.

All patients that have completed the previously announced and ongoing 75 patient Phase IIB and the 375 patient Phase III clinical trials will be given the opportunity to receive six months of Phenserine treatment in an open-label extension study. Patients previously treated with Phenserine can receive Phenserine for an additional six months, while patients previously treated with placebo can receive their initial six-month treatment period with Phenserine. The Phase IIB double-blind placebo-controlled clinical study is designed to examine the effects following six months of Phenserine treatment on the levels of B-APP and amyloid beta (A-B) in the spinal fluid and plasma of mild-to-moderate AD patients. The Phase III double-blind placebo-controlled study will provide efficacy and safety data in mild-to-moderate AD patients following six months of Phenserine treatment.

Open label extension studies are often conducted to generate safety and efficacy data from patients on long-term treatment. Such data could be valuable in order to potentially meet long-term drug exposure requirements that support the safety and chronic use of a drug, set by Regulatory Authorities.

"We feel that it is appropriate to expand the ongoing program to generate these additional long term data following our successful recently completed financing", stated Gosse B. Bruinsma, M.D., Chief Operating Officer, Axonyx Inc. "The ongoing clinical studies are progressing and we expect that the first patients could choose to enter this open label study at the conclusion of their clinical trial protocol."

About Axonyx

Axonyx Inc. is a U.S.-based biopharmaceutical company engaged in the acquisition and development of proprietary pharmaceutical compounds and new technologies useful in the diagnosis and treatment of Alzheimer's disease, human memory disorders and prion-based illnesses such as Mad Cow disease.

This press release may contain forward-looking statements or predictions. These statements represent our judgment to date, and are subject to risks and uncertainties that could materially affect the Company including those risks and uncertainties described in the documents Axonyx files from time to time with the SEC, specifically Axonyx's annual report on Form 10-K. Axonyx cannot assure that the Phase IIB and/or the Phase III clinical trial, or others, if any, with Phenserine will prove successful, that the safety and efficacy profile of Phenserine exhibited in the previous small Phase II trial will remain the same in the Phase IIB and Phase III clinical trials, or future clinical trials, if any, that the preclinical results related to the regulation of beta-APP will be substantiated by the Phenserine Phase IIB clinical trial and that Phenserine will be able to slow the progression of Alzheimer's disease, that the Phase IIB clinical trial data will differentiate Phenserine from the currently marketed drugs, that the efficacy results of the Phase III trial will prove pivotal, that the efficacy data from the Phase IIB clinical trial will be able to be used in the Phase III trial efficacy data, that Axonyx will obtain the necessary financing to complete the Phase III Phenserine trials, that the Company's development work on Phenserine will support an NDA filing, that the results of the Phase III trials will allow Phenserine to be approved by the FDA, that the FDA will grant marketing approval for Phenserine, that if Phenserine is approved by the FDA, it will prove competitive in the market, and that Axonyx will obtain licensing or corporate partnership agreements that will enable acceleration of the development of and optimize marketing opportunities for, Phenserine, or that Axonyx will be able to advance any other potential memory enhancing compound toward IND status. Axonyx undertakes no obligation to publicly release the result of any revisions to such forward-looking statements that may be made to reflect events or circumstances after the date hereof or to reflect the occurrence of unanticipated events.