Questcor Announces FDA Approval of Acthar API Manufacturing Transfer.

UNION CITY, Calif. -- Questcor Pharmaceuticals, Inc. (AMEX:QSC), a specialty pharmaceutical company that develops and commercializes novel therapeutics for the treatment of neurological disorders, today announced that the Food and Drug Administration ("FDA") has approved its application to transfer the manufacturing process of the Active Pharmaceutical Ingredient ("API") of H.P. Acthar(R) Gel, Questcor's largest product. Acthar API will now be manufactured by BioVectra dcl ("BioVectra") of Charlottetown, Prince Edward Island, Canada. Additionally, the FDA approved the transfer of two bioassays required for testing and release of Acthar API and H.P. Acthar(R) Gel finished vials to Product Safety Laboratories of Dayton, New Jersey.

Questcor acquired Acthar from Aventis Pharmaceuticals, Inc. ("Aventis", now ZLB Behring) in 2001, and began the transition of the manufacturing of Acthar API and of Acthar finished vials from Aventis to new contract manufacturers in early 2003. In July 2003, Questcor completed the first step in this transition, the transfer of the Acthar final fill and packaging process to Chesapeake Biological Laboratories of Baltimore, Maryland. This transfer was approved by the FDA in January 2004. Now that the FDA has approved the transfer of the Acthar API manufacturing process and the two bioassays, only the Acthar potency bioassay remains to be transferred to a new contract laboratory and approved by the FDA.

"FDA approval of the Acthar API manufacturing transfer accomplishes a major corporate goal that was established when this product was acquired," said Dave Medeiros, Vice President of Manufacturing at Questcor. "The success of this transfer is directly attributable to strong partnerships between Questcor, BioVectra and ZLB Behring, plus the cooperation and dedication of the BioVectra and ZLB Behring personnel involved with this project."

H.P. Acthar(R) Gel is a natural source, highly purified preparation of the adrenal corticotropin hormone ("ACTH"). Unlike synthetic ACTH, Acthar is specially formulated to provide prolonged release after intramuscular or subcutaneous injection. It works by stimulating the adrenal cortex to secrete the natural endogenous corticosteroids, including cortisol, corticosterone, aldosterone, and a number of weakly androgenic substances.

About Questcor

Questcor Pharmaceuticals, Inc.(R) (AMEX: QSC) is a specialty pharmaceutical company that develops and commercializes novel therapeutics for the treatment of neurological disorders. Questcor currently markets four products in the U.S.: H.P. Acthar(R) Gel (repository corticotropin injection), an injectable drug that is commonly used for certain neurological conditions; Nascobal(R), the only prescription nasal gel formulation of Cyanocobalamin USP (Vitamin B12), that is approved for patients with B12 deficiency caused by malabsorptive disorders resulting from structural or functional damage, such as bariatric surgery, Crohn's disease and certain neurological conditions; Ethamolin(R) (Ethanolamine Oleate), an injectable drug used to treat enlarged weakened blood vessels at the entrance to the stomach that have recently bled, known as esophageal varices; and Glofil-125(R), which is an injectable agent that assesses how well the kidney is working by measuring glomerular filtration rate, or kidney function.

Note: Except for the historical information contained herein, this press release contains forward-looking statements that involve risks and uncertainties. Such statements are subject to certain factors, which may cause Questcor's results to differ from those reported herein. Factors that may cause such differences include, but are not limited to, Questcor's ability to accurately forecast and create the demand for each of its products, the gross margins achieved from the sale of those products, Questcor's ability to enforce its exchange policy, the accuracy of the prescription data purchased from independent third parties by Questcor, the sell-through by Questcor's distributors, the inventories carried by Questcor's distributors, and the expenses and other cash needs for the upcoming periods, Questcor's ability to obtain finished goods from its sole source contract manufacturers on a timely basis if at all, Questcor's need for additional funding, uncertainties regarding Questcor's intellectual property and other research, development, marketing and regulatory risks, and, to the ability of Questcor to implement its strategy and acquire products and, if acquired, to market them successfully as well as the risks discussed in Questcor's report on Form 10-K for the calendar year ended December 31, 2004 and other documents filed with the Securities and Exchange Commission. The risk factors and other information contained in these documents should be considered in evaluating Questcor's prospects and future financial performance.

Questcor undertakes no obligation to publicly release the result of any revisions to these forward-looking statements, which may be made to reflect events or circumstances after the date hereof or to reflect the occurrence of unanticipated events.