Is there any common english answer explaining how various
anticoagulants work? EDTA,Sodium Fluroide,Sodium Heparin, Lithium
Heparin, Potassium Oxalate.
I am having mid-terms next week and I really have not grasped the concept
yet. All I understand is that they prevent the clotting of blood. That is
not good enough!
Blood clotting is actually a very complicated process. There are two
pathways-the intrinsic system and the extrinsic system and there are 12 steps
in the pathway for a blood clot to form. If you think about it, you don't
want blood clots to form unless you really need them, so there are many steps
which must be completed. When you first get an injury, the cells lining the
capillaries are damaged and they release a chemical which attracts platelets
to the area. The platelets are cells which stick together and form a
temporary plug until a clot can be made. Then platelets release a factor
which starts the clotting process on its way. Each step must happen in the
right order for a clot to be finally formed. Also, some of the steps require
chemicals such as calcium. So.... anticoagulants interrupt the process
somewhere along the way. EDTA, sodium citrate and potassium oxalate for
instance remove calcium from the blood. Heparin interrupts the last few
steps of the process preventing thrombin from becoming fibrin. Diseases like
Hemophilia are caused by lack of certain factors needed in steps along the
way-ie. hemophilia is a lack of factor VIII (not actually the 8th step, they
were named in the order they were discovered!) Hope this helps.
Hi Pat! Yes they are substances that prevent blood
clotting and so they are called anti-coagulants.
Blood coagulation is a very complex phenomena and
it is not easy to explain it without the use of
some biological terms.
The anti-coagulation action is one that cuts
of difficult that process at some of its stages.
Let's see if telling you quite simply the
coagulation process will let you undestand
the anti-coagulation one.
When a blood vessel is broken, blood escapes as
long as the flesh wound still is open, and the
pressure within the vessel exceeds the outside
one.Pressure can be equalized by different factors.
Anyway usually shed blood clots quickly.
Coagulation is a change that is studied by many
scientists with different theories.
The clotting of blood is due to the sudden appearance
of fibres that entangle the blood cells.
During the very complex process, it occours
the formation of a polymerized protein called fibrin
from another protein, the fibrinogen.
Fibrinogen is produced by the liver and is converted
to fibrin by the way of thrombin.
Thrombin does not exist in the normal circulation
but is generated from a precursor, the prothrombin.
Now prothrombin is a rather stable protein formed in
the liver by a process requiring vitamin K,
and any deficiency of this vitamin depress the
production of prothrombin and also of other
Anyway if intravascular blood clotting is not
prevented immediate death happens as the
result. So there are natural inhibitory systems
that destroy every activated clotting factor
within a few seconds in the bloodstream.Their
action, natural or induced (by drugs), correspond
to the inhibition of the clot formation mentioned
above.Six different factors inhibit thrombin
formation. This action is greatly enhanced by
heparin, a substance formed by connective
In a simple way we can say that the anticoagulant
effect of any drug is to disturb the coagulation
process.This can be done at different stages
during that complicated process, acting
differently upon the place and stage.
Hope that helps you, and thanks for
(Dr) Mabel Rodrigues
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Update: June 2012