Questcor Updates Revenue Guidance for 2004 and Reports on Progress of Acthar Manufacturing Transfer.

UNION CITY, Calif. -- Questcor Pharmaceuticals, Inc. (AMEX:QSC), a specialty pharmaceutical company, announced today that it has revised its revenue guidance for 2004. The previous guidance for 2004 was $16 million to $17 million in net product sales. The updated guidance is around $18 million in net product sales, due in part to increased sales of and demand for H.P. Acthar(R) Gel in the fourth quarter of 2004. Although this increase in Acthar volume may not be sustainable, preliminary sales data indicates that it has been sustained through early February 2005. Questcor expects to announce results for the fourth quarter and for the full year in early March 2005.

Questcor also announced that the first lot of Acthar Bulk, the active pharmaceutical ingredient in the H.P. Acthar(R) Gel final product, was successfully manufactured by Questcor's new contract manufacturer, BioVectra dcl of Charlottetown, Prince Edward Island, Canada. Testing of this lot was successful in that all test results met specification. Questcor recently filed an NDA Supplement with the FDA seeking approval for this manufacturing site transfer, and will use this Acthar Bulk lot to formulate into Acthar Gel after FDA approval is obtained.

Questcor also announced that it has made a required payment of $2.0 million to Nastech Pharmaceutical Company Inc. following the recent FDA approval of the Nascobal (Cyanocobalamin, USP) spray for intranasal administration. Under the terms of its purchase agreement in 2003 for Nascobal gel, a currently marketed Questcor product, Questcor purchased the rights to the Nascobal spray from Nastech. Questcor is currently assessing the spray and its commercialization plans.

Additionally, Questcor announced that its co-promotion agreement with Sigma-Tau Pharmaceuticals for VSL#3(R) expired in January 2005, in accordance with its terms.

About Questcor

Questcor Pharmaceuticals, Inc.(R) (AMEX:QSC) is a specialty pharmaceutical company that acquires, markets and sells brand name prescription drugs for neurological and gastrointestinal use through a U.S. direct sales force and international distributors. Questcor currently markets four products in the U.S.: 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; H.P. Acthar(R) Gel (repository corticotropin injection), an injectable drug that is commonly used for 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 the demand for each of their 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, 2003 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.