Dainippon Acquires Exclusive Rights to Proprietary Drug Research Technology From Questcor.

Business Editors/Health &Medical Writers

HAYWARD, Calif.--(BW HealthWire)--Feb. 3, 2000

Questcor Pharmaceuticals, Inc. (AMEX:QSC) today announced that it has agreed to license exclusive rights to certain aspects of Questcor's proprietary drug research technology to Dainippon Pharmaceutical Co. Ltd., Osaka, Japan.

A memorandum of understanding was signed between the two companies on January 26, 2000 amending the original collaboration agreements between Questcor and Dainippon.

In exchange for a $2 million cash payment, future milestone payments and royalty payments, Questcor has granted an exclusive, world-wide license to Dainippon to use Questcor ppGpp Degradase and Peptide Deformylase technology for the research, development and commercialization of pharmaceutical products.

Questcor has retained the right, as provided in the original collaboration and licensing agreements between the companies, to co-promote, in Europe and the United States, certain products resulting from the arrangement. Both companies have agreed to terminate the antibacterial research collaboration that was established on January 27, 1998 between the two companies.

The original agreement anticipated a third year of research collaboration between the two firms. However, the progress of the program has resulted in Dainippon's desire to have greater participation than originally anticipated. Hence, all drug discovery efforts at Questcor will cease and will be transferred to Dainippon in Osaka.

&uot;We are very pleased to have quickly come to terms with Dainippon for the acquisition of exclusive rights to our ppGpp Degradase and Peptide Deformylase research technology. During the past 2 years, this technology has been the basis for a very productive research collaboration between Dainippon and Questcor, which targets novel anti-bacterial compounds. We are looking forward to Dainippon continuing the effort to commercialize our technology,&uot; commented Charles J. Casamento, Chairman, President and CEO of Questcor.

Upon closing the merger between Cypros and RiboGene on November 17, 1999, Questcor made a commitment to a strategy of development and marketing of late stage specialty pharmaceutical products. &uot;Now that Dainippon has assumed the responsibility to continue the program of discovery and development of our antibacterial compounds,&uot; said Mr. Casamento, &uot;we will be able to re-deploy our financial resources toward the development of our late stage products in phase II and phase III clinical research.&uot;

Dainippon is a 100 year old pharmaceutical company with its principal offices located in Osaka, Japan and has over 2,600 employees. Infectious disease is one of Dainippon's four principal areas of product development focus. Dainippon has over 30 years of experience in the development and marketing of quinolone antibacterial drugs and in 1998, approximately 23% of their pharmaceutical revenues resulted from the sale of antiinfectives.

Questcor Pharmaceuticals, Inc. is a fully integrated specialty pharmaceutical company whose focus is to serve the needs of the acute care and critical care hospital market. The Company's strategy includes the acquisition and marketing of hospital pharmaceutical products, the generation of revenue streams from these products and the continued funding of late stage, acute care and critical care pharmaceutical research and development programs.

Questcor was created as a result of the merger, on November 17, 1999, of RiboGene, Inc. and Cypros Pharmaceutical Corp.

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 the companies' results to differ. Factors that may cause such differences include, but are not limited to, the company's need for additional funding, uncertainties regarding the company's intellectual property and other research, development, marketing and regulatory risks as well as the risks discussed in Cypros' Annual Report on Form 10-K for the fiscal year ended July 31, 1999 and the Risk Factor section of Cypros' Registration Statement (No. 333-25661), RiboGene's Annual Report on Form 10-K for the fiscal year ended December 31, 1998 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.