KOS AND BARR ANNOUNCE DEFINITIVE CO-PROMOTION, MANUFACTURING, AND SETTLEMENT AGREEMENTS

Exhibit 99.1

KOS AND BARR ANNOUNCE DEFINITIVE CO-PROMOTION, MANUFACTURING, AND
SETTLEMENT AGREEMENTS

WOODCLIFF, NJ and CRANBURY, NJ, April X, 2005 – Kos Pharmaceuticals, Inc. (Nasdaq: KOSP) and Barr Pharmaceuticals, Inc. (NYSE: BRL) today announced that that they have signed Co-Promotion, Licensing and Manufacturing, and Settlement and License Agreements relating to the resolution of the patent litigation involving Kos’ Niaspan ^® products. The United States District Court for the Southern District of New York entered into a Consent Dismissal ending the pending litigation between the two companies. These arrangements have been established to provide benefits to millions of female patients who have multiple lipid disorders and are candidates for Kos’ niacin-based pharmaceutical cholesterol products.

Co-Promotion Agreement

The Co-Promotion Agreement provides that Kos and Duramed Pharmaceuticals, a subsidiary of Barr Pharmaceuticals, will co-promote the current Niaspan and Advicor ^® products, as well as future dosage formulations, strengths or modified versions of those products (“the Products”), to obstetricians, gynecologists and other practitioners with a focus on women’s healthcare in the United States using a Duramed specialty sales force. Under the terms of the seven-year agreement (with renewal rights), Kos will train a 40-person Duramed specialty sales force, which will begin promoting the Products in mid-2005. In consideration of the Co-Promotion, Kos will pay Duramed royalties based on quarterly and yearly net sales of the Products, subject to certain maximum sales levels. The Co-Promotion would address a new discrete population of obstetricians, gynecologists and other practitioners with a focus on women’s healthcare who have not previously been detailed on Kos’ cholesterol products. Kos’ cholesterol products could directly serve the growing need to treat the risks of cardiovascular disease in the 28 million women identified by the American Heart Association (AHA) who require HDL-C (the “good” cholesterol) raising therapy.

In February 2004, the AHA raised its guidelines for HDL-C in women from 40 mg/dl to 50 mg/dl. The new guidelines also recommended that women maintain triglycerides levels below 150 mg/dl, a 25% change from past guidelines. These new guidelines essentially tripled the number of women who are candidates for Niaspan and Advicor therapy to about 28 million.

At the same time, a second study published in Circulation found that nearly two-thirds of women at highest risk for a heart attack receive no treatment at all, despite having levels of “good” and “bad” cholesterol that endanger them . Only 7 percent of women had lipid levels considered optimal by the AHA women’s guidelines issued last year (LDL-C of less than 100mg/dL and HDL-C above 50 mg/dL).

Settlement and License Agreement

The Settlement and License Agreement permits Barr Laboratories to launch generic versions of Niaspan and Advicor , as well as future dosage formulations, strengths or modified versions of the Products, under terms of an exclusive license commencing on September 20, 2013, approximately four years earlier than the last-to-expire Kos patent. Upon launch, Barr would pay Kos a royalty equal to a portion of profits generated from the sales of generic versions of the Products. As part of the settlement, Barr admits that Kos’ patents are valid and enforceable and that Barr infringes the Kos patents.

License and Manufacturing Agreement

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