MSD's Investigational MK-0524 Significantly Reduced Flushing Caused By Extended-Release Niacin in Phase II Study

In data presented today at the American Heart Association's
Scientific Sessions 2006 in Chicago, coadministration of MK-0524, an
investigational DP1-receptor antagonist, with extended-release niacin
(ERN) significantly reduced flushing in patients with dyslipidemia
compared to those patients who took ERN alone. Flushing, characterized
by redness of the skin with warming or burning on the face and neck
caused by the dilation of blood vessels near the skin, is a common
niacin-induced side effect that can cause discomfort to patients and
is a significant factor leading to discontinuation of niacin therapy.

Merck & Co., Inc., Whitehouse Station, NJ, USA, known as Merck
Sharp & Dohme (MSD) in many other parts of the world, is developing
MK-0524A. MK-0524A is an investigational compound that combines the
Company's own extended-release niacin with MK-0524, with the intent to
deliver niacin in a pill with reduced flushing. MK-0524A is currently
in Phase III clinical trials for use as monotherapy or when
administered with a statin.

"Previous outcomes studies have shown that niacin has proven
efficacy in reducing cardiovascular events and favorable effects on
HDL cholesterol and triglyceride levels. It has been frustrating
because its use has been limited by flushing," said Christie M.
Ballantyne, M.D., associate chief and professor of medicine, Baylor
College of Medicine, and co-author of the study. "These data
demonstrated that MK-0524 significantly decreased the incidence and
intensity of the flushing that occurred in many patients taking
extended-release niacin compared to that experienced by patients
taking extended-release niacin plus placebo."

About the Study

In the eight-week Phase II study, 412 patients with dyslipidemia
were randomized to one of four groups: 1) ERN 1 g (given as
Niaspan(R)), 2) ERN 1 g plus MK-0524, 3) ERN 1 g plus placebo, or 4)
double placebo daily, for four weeks, with doubling of the respective
doses for the remaining four weeks. After starting treatment, patients
reported flushing intensity in an electronic diary using the validated
numerical and descriptive 11-point Global Flushing Severity Score
(none (GFSS 0), mild (1-3), moderate (4-6), severe (7-9) or extreme
(10)).

All doses of MK-0524 plus ERN were effective in significantly
reducing flushing intensity during both the initiation phase (week 1)
and maintenance phase (week 2-8) when compared to patients taking ERN
alone. During the first week of therapy with ERN alone, 61 percent of
patients (42/69) reported clinically significant moderate, severe or
extreme flushing (GFSS greater than or equal to 4) compared to 37
percent of patients (97/266) treated with ERN administered with
MK-0524 (pooled data from all doses). Thirteen percent of patients
(9/67) treated with double placebo experienced moderate or worse
flushing. During the maintenance phase (weeks 6 to 8), the rate of
moderate or severe ERN-induced flushing for patients treated with
MK-0524 given with ERN was similar to patients treated with placebo.

Over the eight-week treatment period, all measured lipid
parameters were very favorably affected; ERN + MK-0524 increased HDL-C
by 22.9 percent and reduced LDL-C and TG by 13.2 percent and 26.5
percent, respectively. There was no difference in lipid response when
MK-0524 with ERN was compared to treatment with ERN alone. There was a
low incidence of adverse experiences in this study.

Ongoing Clinical Program

"MK-0524A is currently being studied in a large Phase III program.
MSD's commitment to the development of MK-0524A is supported by our
ongoing clinical program, which includes a cardiovascular events
outcomes study and a newly announced surrogate endpoint study," said
John F. Paolini, M.D., Ph.D, senior director clinical research,
cardiovascular disease, MSD. Late-stage clinical trials to support
MK-0524B continue, with MK-0524A coadministered with simvastatin, as
the Company continues to work on developing the fixed-dose combination
formulation.

MSD has recently begun screening patients for ACHIEVE (An
Assessment of Coronary Health Using an Intima-Media Thickness Endpoint
for Vascular Effects Study), a two-year multinational carotid
ultrasound study in 900 patients with heterozygous familial
hypercholesterolemia to assess the effect of MK-0524A on the change in
carotid artery intima-media thickness. Patients will receive intensive
LDL-C lowering therapy throughout the study and will be randomized to
receive MK-0524A or placebo at 2 g/day for up to 96 weeks.

As previously announced, in early 2007 investigators will begin
screening patients with vascular disease into the HPS2-THRIVE
(Treatment of HDL to Reduce the Incidence of Vascular Events) study to
investigate whether MK-0524A can further reduce the risk of heart
attacks, strokes and revascularization procedures among people who are
already being treated to lower their LDL, or "bad" cholesterol levels.
The researchers also will be examining the long-term safety profile of
MK-0524A.

A total of 20,000 men and women aged 50 to 80 years with a history
of heart attack, stroke, peripheral arterial disease, or other
coronary disease in the presence of diabetes are being recruited in
three regions: the UK (7,500), China (7,500) and Scandinavia (5,000
from Denmark, Norway, Finland and Sweden). Up to 7,000 patients in the
study will have diabetes. HPS2-THRIVE is being coordinated at Oxford
University by the Clinical Trial Service Unit (CTSU), with a grant
from MSD.

About Merck & Co., Inc. (Whitehouse Station, NJ, USA)

Merck & Co., Inc., which operates in many countries as Merck Sharp
& Dohme (MSD) is a global research-driven pharmaceutical company
dedicated to putting patients first. Established in 1891, Merck
currently discovers, develops, manufactures and markets vaccines and
medicines to address unmet medical needs. The Company devotes
extensive efforts to increase access to medicines through far-reaching
programs that not only donate Merck medicines but help deliver them to
the people who need them. Merck also publishes unbiased health
information as a not-for-profit service. For more information, visit
www.merck.com.

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