IMPAX Announces Court of Appeals Remands Earlier Riluzole Patent Validity Decision Back to Lower Court

November 22, 2006

HAYWARD, Calif.--(BUSINESS WIRE)--Nov. 22, 2006--IMPAX Laboratories, Inc. (OTC: IPXL) ("IMPAX" or "the Company") today announced that the United States Court of Appeals for the Federal Circuit ruled that the district court had erred in deciding, after trial, that the patent relating to the use of riluzole in treating ALS (Pat. No. 5,527,814) was valid and has vacated that decision and remanded it back to the district court for further proceedings related to the validity issue of anticipation. On December 12, 2002, in an earlier decision, the United States District Court for the District of Delaware granted a preliminary injunction motion brought by Aventis on October 15, 2002, which delayed IMPAX's entry into the market. IMPAX's ANDA for its generic version of Rilutek(R) (riluzole) 50mg tablets was approved on January 29, 2003. IMPAX expects to request that the injunction preventing the Company from launching its generic version of Rilutek(R) be lifted upon return of the case to the lower court.

Rilutek(R), marketed by Aventis for the treatment of amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease, had U.S. sales of approximately $37 million for the 12 months ended August 31, 2006, according to Wolters Kluwer Health.

"We are pleased that the Federal Circuit decided to remand this case back to the lower court as we believe that it is important to make an affordable alternative available to patients suffering from ALS," commented Larry Hsu, Ph.D., President and CEO of IMPAX Laboratories. "We continue to remain optimistic about the eventual outcome of this patent validity challenge."

About IMPAX Laboratories, Inc.

IMPAX Laboratories, Inc. is a technology based specialty pharmaceutical company applying its formulation expertise and drug delivery technology to the development of controlled-release and specialty generics in addition to the development of branded products. IMPAX markets its generic products through its Global Pharmaceuticals division and markets its branded products through the IMPAX Pharmaceuticals division. Additionally, where strategically appropriate, IMPAX has developed marketing partnerships to fully leverage its technology platform. IMPAX Laboratories is headquartered in Hayward, California, and has a full range of capabilities in its Hayward and Philadelphia facilities. For more information, please visit the Company's Web site at:

"Safe Harbor" statement under the Private Securities Litigation Reform Act of 1995:

To the extent any statements made in this news release contain information that is not historical, these statements are forward-looking in nature and express the beliefs and expectations of management. Such statements are based on current expectations and involve a number of known and unknown risks and uncertainties that could cause IMPAX's future results, performance or achievements to differ significantly from the results, performance or achievements expressed or implied by such forward-looking statements. Such risks and uncertainties include, but are not limited to, possible adverse effects resulting from the delisting of IMPAX's stock, IMPAX's delay in filing its 2004 Form 10-K, its Form 10-Q for each of the first three quarters of 2005, its Form 10-K for 2005, and its Form 10-Q for each of the first two quarters of 2006, IMPAX's ability to obtain sufficient capital to fund its operations, the difficulty of predicting FDA filings and approvals, consumer acceptance and demand for new pharmaceutical products, the impact of competitive products and pricing, IMPAX's ability to successfully develop and commercialize pharmaceutical products, IMPAX's reliance on key strategic alliances, the uncertainty of patent litigation, the availability of raw materials, the regulatory environment, dependence on patent and other protection for innovative products, exposure to product liability claims, fluctuations in operating results and other risks detailed from time to time in IMPAX's filings with the Securities and Exchange Commission. Forward-looking statements speak only as to the date on which they are made, and IMPAX undertakes no obligation to update publicly or revise any forward-looking statement, regardless of whether new information becomes available, future developments occur or otherwise.

CONTACT: IMPAX Laboratories, Inc.
Larry Hsu,
Ph.D. President & CEO,
Ext. 1111
Arthur Koch,
Investor Relations Contacts:
Lippert/Heilshorn & Associates, Inc.
Kim Sutton Golodetz,
Bruce Voss,

SOURCE: IMPAX Laboratories, Inc.