Kos Reports Summary Results from Clinical Study on Benefits of Combining Aspirin with Optimized Niaspan(R) CF

-- The study shows that 2000 mg of optimized Niaspan(R) CF, when given with aspirin, results in approximately 44% reduction in the incidence, duration and severity of flushing relative to optimized Niaspan CF alone

-- The study results are in addition to previously reported decreases in flushing severity and duration when comparing optimized Niaspan CF to currently available Niaspan in the absence of aspirin

-- A supplemental New Drug Application for a complete dosage range of new Niaspan CF products was recently submitted to the Food and Drug Administration

-- Additional longer term and confirmatory studies are planned

Kos Pharmaceuticals, Inc. (Nasdaq:KOSP) today announced resultsfrom a study that demonstrates the benefits of combining aspirin withits new optimized Niaspan(R) (niacin extended-release tablets) CapletFormulation (CF). This study was a single-dose, placebo-controlledthree-way crossover, flush provocation study (N=156) evaluating thebenefits of aspirin in combination with a maximum dose of optimizedNiaspan CF for reducing the incidence, duration and severity offlushing, a relatively common, but transient effect for patients whotake Niaspan to increase HDL-C, or "good" cholesterol.

In this flush provocation study, subjects were administered 650 mgof aspirin either 30 minutes before or at the same time as a singledose of 2000 mg of optimized Niaspan CF. Results show statisticallysignificant reductions in the incidence (number of subjects reportinga flush) and intensity of flushing, compared to placeboadministration. Flushing symptoms and duration data were recorded inan electronic diary. Even though the study was specifically designedto provoke flushing by administering 2000 mg of optimized Niaspan CFto treatment-naive subjects, only about one-half of the subjectsreported a flush with optimized Niaspan CF plus aspirin. In addition,the flushing that did occur was generally reported to be mild.Flushing duration was also reduced. There were no significantdifferences in the incidence, duration or severity of flushing whenaspirin was administered either 30 minutes prior to, or simultaneouswith, the dosing of optimized Niaspan CF. Other characteristics offlushing including redness, warmth, tingling and itching, were allalso reduced with optimized Niaspan CF and aspirin compared toplacebo.

"Data from this study represents the latest output from a longterm, multifaceted development program initiated several years agowhich was designed to enhance the tolerability of Niaspan bycapitalizing on Kos' expertise, knowledge and strengths inreformulation and product development," said Adrian Adams, Presidentand CEO of Kos Pharmaceuticals. "The benefits of aspirin in reducingniacin-induced flushing have been known for many years, and so thenext stage in the natural evolution and life-cycle management of ourHDL boosting franchise was to test the combination of aspirin with thenew optimized Niaspan CF, a reformulation of Niaspan that was recentlyshown in a previously announced clinical study to decrease theseverity and duration of flushing by around 42%." He continued,"Furthermore, aspirin use is well established and is not known to beassociated with adverse cardiovascular side effects that have recentlycome to light with some other, non-aspirin nonsteroidalanti-inflammatory agents."

Kos recently announced the submission of a supplemental New DrugApplication for a complete dosage range of Niaspan CF products forreview to the U.S. Food and Drug Administration. The Company isplanning for a first quarter 2007 launch of the new range of NiaspanCF products.

About Niaspan

Available since 1997, Niaspan is the only FDA-approved, once-dailyextended-release prescription formulation of niacin for treatingabnormal cholesterol levels. Niaspan is indicated as an adjunct todiet when the response to a diet restricted in saturated fat andcholesterol and other nonpharmacologic measures alone has beeninadequate, to reduce elevated total cholesterol, LDL-C, Apo B, andtriglyceride levels, and to increase HDL-C in patients with primaryhypercholesterolemia and mixed dyslipidemia. In patients with ahistory of myocardial infarction and hypercholesterolemia, niacin theactive ingredient in Niaspan, is indicated to reduce the risk ofrecurrent non-fatal myocardial infarction or coronary artery diseaseand hypercholesterolemia. Niacin, in combination with a bile acidbinding resin, is indicated to slow progression or promote regressionof atherosclerotic disease.

Niaspan is contraindicated in patients with allergies to any ofits ingredients, active peptic ulcer disease, significant orunexplained persistent liver dysfunction, or arterial bleeding.Niaspan should not be substituted for equivalent doses ofimmediate-release niacin. Niaspan should be prescribed with caution inpatients who consume substantial amounts of alcohol and/or have a pasthistory of liver disease. Liver function tests should be performed onall patients during therapy with Niaspan. Use of Niaspan with otherlipid-altering medications called statins may increase the risk ofrhabdomyolysis, a rare condition that causes muscles to breakdown. Themost common side effect with Niaspan is flushing of the skin. Othercommonly reported side effects include indigestion, headache, pain,abdominal pain, nausea, itching, diarrhea, running nose, vomiting andrash. Patients with diabetes should carefully monitor their bloodsugar and report changes to their doctor.

About Kos Pharmaceuticals, Inc.

Kos Pharmaceuticals, Inc. is a fully integrated specialtypharmaceutical company engaged in developing, commercializing,manufacturing and marketing proprietary prescription products for thetreatment of chronic diseases with a particular focus on thecardiovascular, metabolic and respiratory disease areas. The Company'sprincipal product development strategy is to reformulate existingpharmaceutical products with large market potential to improve safety,efficacy, and patient compliance. Kos' strategy also includes makingmeasured investments in new chemical entity research through in-houseand sponsored research, scientific in-licensing and general corporatedevelopment activities. The Company currently markets Niaspan andAdvicor(R), Azmacort(R), Cardizem(R)LA, and Teveten(R) andTeveten(R)HCT. Kos has a strong and growing research and developmentpipeline including proprietary drug delivery technologies insolid-dose, inhalation and aerosol metered-dose device administrationto help fuel sustained, organic sales growth into the future.

Certain statements in this press release, including statementsrelating to Niaspan CF (including optimized Niaspan CF), the timing ofthe launch of the new range of Niaspan CF products (includingoptimized Niaspan CF), the Company's strong and growing research anddevelopment pipeline and future sales growth are forward-looking andare subject to risks and uncertainties which may cause actual resultsto differ materially from those projected in a forward-lookingstatement. These risks and uncertainties include market acceptance ofNiaspan CF (including optimized Niaspan CF), the protection affordedby the Company's patents and those related to its acquired andlicensed products, the ability to build awareness for the Company'sproducts, including Niaspan CF and optimized Niaspan CF, within themedical community, the continuing growth of the cardiovascular,respiratory and allergy markets, the Company's ability to increase thesize of its sales force and to attract and retain sales professionals,the Company's and its licensors' ability to achieve regulatoryapprovals for products under development and to successfully launchsuch products in a timely manner, the ability of third party suppliersto the Company continuing to be able to perform their supplyobligations, the Company's ability to entered into additional newbusiness development opportunities, the progress of the Company'sresearch and development pipeline, the effect of conditions in thepharmaceutical industry and the economy in general, as well as certainother risks. A more detailed discussion of risks attendant to theforward-looking statements included in this press release are setforth in the "Forward-Looking Information: Certain CautionaryStatements" section of the Company's Annual Report on Form 10-K forthe year ended December 31, 2005, filed with the Securities andExchange Commission, and in other reports filed with the SEC. Allinformation in this press release is as of July 25, 2006 and theCompany undertakes no duty to update this information.