IMPAX Announces Shire's Lawsuit Related to Generic Version of Adderall XR

October 24, 2005

HAYWARD, Calif.--(BUSINESS WIRE)--Oct. 24, 2005--IMPAX Laboratories, Inc. (OTC:IPXL) today announced that an affiliate of Britain's Shire Pharmaceuticals Group Plc ("Shire") has filed a complaint against the Company in the United States District Court for the Southern District of New York, alleging patent infringement related to a third patent for Adderall XR. The Company has not yet been served with the complaint. IMPAX has submitted its ANDA filing with the U.S. Food and Drug Administration (FDA) under Paragraph IV of the Hatch-Waxman Amendments, stating that it believes its generic versions of Adderall XR tablets do not infringe the two patents listed in the FDA's "Orange Book" or that those two listed patents are invalid or unenforceable. The Company is currently in litigation with Shire in the United States District Court for the District of Delaware regarding Shire's claim that the Company's ANDA infringes the two Orange Book listed patents, with a trial date scheduled for February, 2006. The patent at issue in this recent complaint was not listed in the FDA "Orange Book" and therefore was not included in the Company's previous Paragraph IV certification, however, the Company believes that its generic versions of Adderall XR tablets do not infringe this third patent or that this patent is also invalid or unenforceable.

Adderall XR is marketed by Shire for attention deficit hyperactivity disorder (ADHD). According to NDCHealth, U.S. sales of Adderall XR tablets were approximately $770 million in the 12 months ended July 31, 2005.

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 intends to market 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. In particular, the forward-looking statements include statements about IMPAX's estimated timelines and new application filing goals. 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 and its Form 10-Q's for the first two quarters of 2005, 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.
Barry R. Edwards, 215-933-0323 Ext. 4360
Arthur A. Koch, Jr., 215-933-0351
Larry Hsu, Ph.D., 510-476-2000 Ext. 1111
Investor Relations Contacts:
Lippert/Heilshorn & Associates, Inc.
Kim Sutton Golodetz, 212-838-3777
Bruce Voss, 310-691-7100

SOURCE: IMPAX Laboratories, Inc.