Questcor Files sNDA for Treatment of Infantile Spasms with H.P. Acthar® Gel; FDA Accepts Application for Review

Business Wire, August 23, 2006

UNION CITY, Calif. -- Questcor Pharmaceuticals, Inc. (AMEX:QSC) announced today that the U.S. Food and Drug Administration (FDA) has accepted for review its supplemental new drug application (sNDA) seeking approval for H.P. Acthar(R) Gel (repository corticotropin injection) for the treatment of infantile spasms. Questcor anticipates that the FDA will take action on the sNDA during the second quarter of 2007. No drug is currently approved in the United States for the treatment of infantile spasms.

"Today's announcement demonstrates our continued commitment to the treatment of central nervous system diseases and disorders," said James Fares, Questcor's president and chief executive officer. "Acthar Gel is an important drug today in the treatment of infantile spasms. However, we believe this filing supports an even greater role for Acthar Gel in managing this life-threatening form of childhood epilepsy. We look forward to working closely with the FDA throughout this review process."

The sNDA provides clinical data to support the addition of the infantile spasms indication to the current Acthar Gel label. Supportive information includes historical data on the use of Acthar Gel in the treatment of infantile spasms, including the results from randomized clinical trials involving greater than 250 patients, which were published in peer-reviewed medical literature.

About Infantile Spasms -- Infantile spasms (IS) is a seizure disorder of early childhood also known as West Syndrome. The onset is predominantly in the first year of life, typically between 3 to 6 months. The typical pattern of IS is a sudden bending forward and stiffening of the body, arms, and legs; although there can also be arching of the torso. Spasms tend to begin soon after arousal from sleep. Individual spasms typically last for 1 to 5 seconds and occur in clusters, ranging from 2 to 100 spasms at a time. Infants may have dozens of clusters and several hundred spasms per day. Infantile spasms usually stop by age 5, but are often replaced by other seizure types. IS is characterized by seizures, hypsarrhythmia (abnormal, chaotic brain wave patterns), and mental retardation. Other neurological disorders, such as cerebral palsy, may be seen in 30-50% of those with IS. The incidence of IS is estimated to be about 1 per 2,000 to 4,000 live births. It is the most frequent type of epileptic encephalopathy, the group of conditions in which epilepsy determines cognitive deterioration. No drug is currently approved in the United States for the treatment of IS. Patients diagnosed with this disorder are typically treated with a variety of agents, including Acthar Gel.

About Acthar Gel - H.P. Acthar Gel(R) is a natural adrenocorticotropic hormone (ACTH) designed to provide a prolonged release after intramuscular or subcutaneous injection. Acthar Gel is currently indicated for the treatment of acute exacerbations of multiple sclerosis, and for several other diseases and disorders.

For full prescribing information and safety information on Acthar Gel, please visit http://www.acthar.com.

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 H.P. Acthar(R) Gel (repository corticotropin injection), an injectable drug indicated for the treatment of exacerbations associated with multiple sclerosis and Doral(R) (quazepam) that is indicated for the treatment of insomnia characterized by difficulty in falling asleep, frequent nocturnal awakenings, and/or early morning awakenings. For more information, please visit www.questcor.com.

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 its products, the gross margin achieved from the sale of its products, Questcor's ability to enforce its product returns 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 potential future need for additional funding, Questcor's ability to utilize its net operating loss carry forwards to reduce income taxes on the sale of its non-core products, research and development risks, uncertainties regarding Questcor's intellectual property and the uncertainty of receiving required regulatory approvals in a timely way, or at all, and 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 annual report on Form 10-K for the year ended December 31, 2005 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.