Kos Reports Summary Results of Key Phase IV Research and Development Studies

Kos Pharmaceuticals, Inc. (Nasdaq:KOSP)
-- Kos' optimized Niaspan(R) modified formulation ("MF") shows an
improved overall flushing profile vs. commercialized Niaspan,
with a 42 percent reduction in severity, and a 43 percent
reduction in duration of flushing.

-- COMPELL Study shows significantly greater reductions in
triglycerides and Lp(a), as well as superior 2.5-3.5 fold
increases in HDL-C versus Crestor(R) and Zocor(R)/Zetia(R) and
comparable lowering of LDL-C with Niaspan Combination Therapy.

Kos Pharmaceuticals, Inc. (Nasdaq:KOSP) announced today resultsfrom two studies that represent significant milestones in its researchand development activities: data from a study with an optimizedNiaspan(R) MF dosage strength and data from the COMPELL (COMParativeEffects on Lipid Levels of Niaspan and Statins Versus Other LipidTherapies) Phase IV efficacy trial.

The Niaspan MF Study

This study was a single dose, double-blind, randomized,placebo-controlled three-way crossover, human study (N=156) evaluatinga Niaspan (niacin extended-release tablets) modified formulation forreduction in severity and duration of flushing, a relatively commonand transient nuisance side effect for patients who take Niaspan toincrease HDL-C, or "good" cholesterol.

Niaspan MF is one of the first products to emerge from a dedicatedresearch and development program designed to further enhance thetolerability profile of Niaspan products by taking advantage of Kosexpertise in formulation development. In a study designed to provokeflushing, patients received a single dose of Niaspan MF 2000 mg,regular Niaspan 2000 mg, or placebo. Flushing symptoms and durationwere recorded on an electronic diary. Niaspan MF showed asignificantly improved (p<0.0001) overall flushing profilevs. commercialized Niaspan, with a 42 percent reduction in severity,and a 43 percent reduction in duration of flushing.

Notably, significant reductions in flushing severity and durationwere achieved in the absence of aspirin or other NSAIDco-administration, which is often recommended to mitigate flushingduring the first weeks of therapy when the side effect is most likelyto occur. Most patients will experience at least one flushing episodewhile on Niaspan, and tolerance generally develops during long-termuse.

The COMPELL Study

COMPELL was a 12-week, randomized, multicenter, open-label studyin 292 patients comparing the efficacy of combination therapy withNiaspan and low to moderate doses of Lipitor(R) and Crestor(R) againstmoderate to high dose Crestor and Zocor(R)/Zetia(R) (sold as thefixed-dose combination tablet, Vytorin(R)). In a dose-escalation studydesign, Niaspan 1000 mg with Crestor 10 mg, 20 mg, and Lipitor 20 mg,and Niaspan 2000 mg with Lipitor 40 mg, were compared with Crestor 20mg and 40 mg and Zocor/Zetia 20mg/10mg and 40mg/10 mg.

Study results showed that, for LDL-C, all treatments wereequivalent in their ability to lower LDL-C, achieving ~50% or greaterlowering in LDL-C at both time points evaluated (weeks 8 and 12).However, both Niaspan combinations achieved significantly greater (2.5- 3.5 fold) increases in HDL-C, and significantly greater reductionsin triglycerides and Lp(a) compared to the other two treatment arms.All treatments were well tolerated, with similar numbers of patientsreporting adverse events and serious adverse events. No drug-relatedmyopathy was observed.

"We do not believe that lowering LDL to ultra-low levels is enoughto protect against heart disease," said Adrian Adams, President andCEO of Kos Pharmaceuticals, "There seems to be a diminishing rate ofreturn in the benefit for reducing coronary events as LDL is loweredprogressively below 100 mg/dL. Most LDL-lowering trials show thattwo-thirds to three-quarters of statin-treated patients who are atrisk in fact progress to a cardiovascular event despite treatment."

"Aggressively treating multiple lipid parameters simultaneously isimportant in combating the worldwide epidemic of heart disease," Adamscontinued. "Attention is shifting to raising HDL cholesterol in lightof recent landmark clinical trials demonstrating that lowering LDLcholesterol may have reached its peak in its ability to reduce heartattacks or strokes. HDL is emerging as a major focus as physiciansbegin to look beyond LDL, and Niaspan and its combinations remain wellpositioned for growth, particularly given their highly differentiatedclinical profiles."

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 isindicated to reduce the risk of recurrent non-fatal myocardialinfarction or coronary artery disease and hypercholesterolemia.Niacin, in combination with a bile acid binding resin, is indicated toslow progression or promote regression of 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

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(R) andAdvicor(R) for the treatment of cholesterol disorders, Azmacort(R) forthe treatment of asthma, Cardizem(R)LA for the treatment ofhypertension and angina, and Teveten(R) and Teveten(R)HCT for thetreatment of hypertension. Kos has a strong and growing research anddevelopment pipeline including proprietary drug delivery technologiesin solid-dose, inhalation and aerosol metered-dose deviceadministration to help fuel sustained, organic sales growth into thefuture.

Certain statements in this press release, including statementsrelating to Niaspan, Niaspan MF, the results of the Niaspan MF studyand COMPELL study, the growth prospects of the markets in which theCompany's products compete, including Niaspan and its combinations,are forward-looking and are subject to risks and uncertainties whichmay cause actual results to differ materially from those projected ina forward-looking statement. These risks and uncertainties include,the Company's ability to grow revenue and control expenses, theprotection afforded by the Company's patents and those related to theacquired and licensed products, the ability to build awareness forNiaspan, Advicor, Azmacort, Cardizem LA, Teveten and Teveten HCTwithin the medical community, the continued success of the allianceswith Takeda, Merck KGaA, Oryx, Arisaph, Barr, Biovail and Jerini, thecontinuing growth of the cardiovascular and respiratory markets, theCompany's ability to maintain its compliance with FDA regulations andstandards without adversely affecting the Company's manufacturingcapability or ability to meet its production requirements or profitmargins, the Company's ability to increase the size of its sales forceand to attract and retain sales professionals, and, ensure compliancewith prescription drug sales and marketing laws and regulations,changes in the regulatory environment governing the Company'scompliance with the FDA, PTO, tax and competition issues, the impactof a possible generic version of the Cardizem LA product or otherproducts sold by the Company, the ability of third party suppliers tothe Company continuing to be able to perform their supply obligations,the Company's ability to achieve regulatory approvals for its productsunder development in a timely manner, such as the modified formulationof Niaspan and others, the Company's ability to establish a footprintand generate sales in the hypertension and angina markets, theCompany's ability to successfully negotiate additional importantstrategic business development opportunities, the progress of theCompany's research and development pipeline, fluctuating buyingpatterns by the Company's wholesalers and distributors, the Company'sability to maintain coverage of its products by government agenciesand the effects of the loss of such coverage with such agencies, suchas the Centers for Medicare and Medicaid Services, the effect ofconditions in the pharmaceutical industry and the economy in general,as well as certain other risks. A more detailed discussion of risksattendant to the forward-looking statements included in this pressrelease are set forth in the "Forward-Looking Information: CertainCautionary Statements" section of the Company's Annual Report on Form10-K for the year ended December 31, 2004, filed with the Securitiesand Exchange Commission, and in other reports filed with the SEC. Allinformation in this press release is as of February 23, 2006 and theCompany undertakes no duty to update this information.

Crestor is a registered trademark of AstraZeneca group ofcompanies. Zocor is a registered trademark of Merck & Co, Inc. Zetiaand Vytorin are registered trademarks of MPS Singapore Company, Inc.