Medcan First in Canada to Offer Genetic Testing for Warfarin

    Patients to benefit from reduced risks and side-effects

    TORONTO, Dec. 16 /CNW/ - The Medcan Clinic is the first clinic in Canada
to offer genetic testing to predict a patient's response to warfarin in order
to avoid trial and error prescribing and adverse side-effects.
    "After insulin, the side-effects from warfarin, a popular blood thinner
designed to prevent heart attacks and stroke, send more people to the
emergency room than any other medication," said Medcan's Geneticist, Dr. Lea
Velsher.
    The challenge is that correct dosage of warfarin varies greatly from one
person to the next, which is largely attributable to genetic factors (although
other factors play a role, including an individual's diet, age and other uses
of medications). Precise dosing of warfarin is important since too much can
cause bleeding, leading to devastating, even deadly hemorrhaging. Too little
warfarin can cause clots to form, increasing the risk for stroke.
    This new area of medicine that predicts an individual's response to drugs
based upon genetic makeup is called "pharmacogenomics". By assessing how
specific genetic variants can affect an individual's ability to metabolize
medications, pharmacogenomics allows a physician to reduce trial and error
prescribing and predict which medications and which dosages are least likely
to produce adverse side-effects.
    While genetic testing for the two genes that play a role in how an
individual metabolizes Warfarin is not accessible in Canada, the Medcan Clinic
has formed a relationship with PGXL Laboratories in Louisville Kentucky to
offer testing for warfarin as well as many other drug therapies.

    Two genes have been determined to play in important role in how an
individual processes (metabolizes) warfarin:

    1.  Cytochrome P450 2C9 - this is the primary path of metabolism for
        warfarin. This gene produces an enzyme in the liver, which
        metabolizes warfarin. Some individuals metabolize warfarin more
        slowly based on genetic differences in CYP2C9. These individuals
        would need a lower dose to reach optimal therapeutic levels. 12.2% of
        the population are intermediate metabolizers of CYP2C9; 7.9% of the
        population are slow metabolizers.

    2.  Vitamin K Epoxide Reductase complex 1 (VCORC1) - differences in this
        gene explain approximately 30% of the variation in warfarin dosing in
        the population. Vitamin K is an important component of blood clotting
        and Warfarin inhibits this process. Some genetic mutations in VCORC1
        can cause warfarin to be less active, thereby decreasing its
        effectiveness as a blood thinner. Based on genetic differences in
        VCORC1, individuals may need higher or lower doses for warfarin.

    Combining results of CYP2C9 and VCORC1 testing allows doctors to be more
precise in reaching therapeutic levels of Warfarin and at a faster time.
    In fact, in August of 2007, the FDA updated the labeling for warfarin to
explain that an individual's genetic make up may influence how they respond to
the drug. These labeling updates are based on an analysis of recent studies
that found people respond to the drug differently based, in part, on whether
they have variations of certain genes.
    The Canadian government is also considering revising labeling on warfarin
products.

    About Medcan:

    The Medcan Clinic is a leading preventive health care clinic focused on
identifying health risks before signs and symptoms occur. Medcan offers
individuals, families and corporate executives the most thorough head-to-toe
medical assessment on the market, performed by a top-quality clinical team in
a single 5 hour visit. Medcan also provides an array of in-house health and
wellness services, such as diagnostic imaging, genetics, optometry, fitness
and nutritional counseling, to customize patients' medical care and optimize
healthy outcomes. Patients benefit from Medcan's in-house specialists and
extensive referral network.

For further information: Media Contact: Bronwen Evans, Vice-President,
Corporate Affairs, The Medcan Clinic, (416) 350-8374, bronwenevans@medcan.com;
For information on Medcan Clinic services, contact our bookings team at
bookings@medcan.com or (416) 350-5900