Pharmacokinetic Comparison of Warfarin and Heparin

Running head: PRINCIPLES OF PHARMACOLOGY AND THERAPEUTICS 1
Principles of Pharmacology and Therapeutics
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PRINCIPLES OF PHARMACOLOGY AND THERAPEUTICS 2
My profile drug is warfarin and its generic name is Coumadin. The relevant drug classes
based on ATC classification system of warfarin include:
B- Blood and blood forming organs
B01-Antithrombotic agents
B01A- Antithrombotic agents and
B01AA- Vitamin K antagonists
Warfarin is anticoagulant drug that is used to reduce the risk of blood clotting. It prevents blood
from forming coagulating to form a clot in sensitive organs like lungs, brain and heart. Its indica-
tion includes
-Prophylaxis and treatment of venous thrombosis
-Prophylaxis and treatment of thromboembotic complications that are linked with cardiac valve
replacement and atrial fibrillation.
-Reduction in the risk of death as a result of stroke or systemic embolization, and recurrent my-
ocardial infarction.
-Heart attack

PRINCIPLES OF PHARMACOLOGY AND THERAPEUTICS 3
- Heparin and aspirin

PRINCIPLES OF PHARMACOLOGY AND THERAPEUTICS 4
A study was done to determine the effectiveness of warfarin among ischemic stroke patients
who had atrial fibrillation. Among the participants were 12000 survivors of stroke. Out of
11000, 88 % were treated with warfarin (Ahmed et al., 2010). According to the findings of
the study, patients that were treated with warfarin had more days at home than 1000
patients who had no warfarin therapy. Besides, patients that were discharged on warfarin
therapy had reduced risk of recurrent ischemic stroke. This study provides crucial evidence
that warfarin therapy is effective in treatment of ischemic stroke disease as it improved the
clinical outcomes of the participants with stroke conditions (Adam et al., 2012).
Another study was carried out to compare the efficacy and safety of warfarin therapy verses
left atrial appendage therapy in prevention of stroke in patients with atrial fibrillation.
According to the findings of the research, the efficacy of percutaneous closure of left atrial
appendage was inferior to the warfarin therapy.
A randomized study was carried out to determine the safety and efficacy drug in
comparison to dextron 40 in the prevention of venous thrombosis. The patients who were
selected in the study had a high risk for deep vein thrombosis after elective total knee
replacement. Medication f warfarin was done in a two-step approach in order to avoid any
bleeding complications. Among the participants, 53 patients were treated with warfarin and
37 treated with dextron. According to the findings of the study, measures of blood loss
indicated that there are no difference between patients that were treated with dextran with
these who were treated with warfarin. Also, the findings showed that excessive

PRINCIPLES OF PHARMACOLOGY AND THERAPEUTICS 5
postoperative bleeding was infrequent besides being similar in both therapy groups. The
study demonstrated that the two step approach of warfarin treatment gives highly effective
prophylaxis of postoperative venous thrombosis after knee surgery when compared to
dextron therapy (Adam et al., 2012).
Chemically heparin is a glycosaminoglycan polymer whereas warfarin is organic compound
known as 4-hydroxycoumarins. Both medication works in different ways to inhibit the
production of cofactors of blood clotting.
Warfarin is anticoagulant drug that acts by blocking the formation of clotting factors that
are dependent on vitamin K. This action decreases the ability of the body to form blood
clots. On the other hand, Heparin is anticoagulant drug which acts by binding different
proteins and enzymes thereby preventing fibrin and thrombin from working correctly in the
blood hence making the process of blood clotting and coagulation to stop (Dans et al.,
2013).
Once administered, Warfarin medication requires enough time to build a therapeutic level
in the blood whereas Heparin acts quickly thus mostly used during emergence situation to
quickly stabilize blood circulation to the body. Warfarin is supplied through injectable
intravenous, subcutaneous medication or oral tablet whereas heparin is supplied as an
injectable medication thus it can be administered through intravenous or subcutaneous route
(Dans et al., 2013).
Warfarin is mostly used anticoagulants but since human being differs in their physiological
function, its dosage differs from each individual. Patients under warfarin therapy are
supposed to take their blood tests for every 2 to 3 weeks for confirmation of their blood
thinning degree. On the other hand, heparin is commonly used in hospitals to prevent

PRINCIPLES OF PHARMACOLOGY AND THERAPEUTICS 6
emergence clot and mostly recommended for pregnant women when antiphospholipid
antibodies are discovered. The recommendation for heparin instead of warfarin for pregnant
women is because warfarin can harm the foetus (Björck et al., 2013).
Both warfarin and heparin are anticoagulant used to treat thrombosis and stroke. Besides
both have almost similar side effects which include bleeding, rash, headache and elevated
enzymes. Both drugs have the same indication that is treatment of stroke,
thromboembolism, transient ischemic attack and myocardial infarction.
Although Warfarin has various indications, its mechanism of action is the same with that of
heparin. Its mechanism of action for these multiple indications is antagonising the action of
vitamin K that leads to production of clotting proteins. It acts by blocking the formation of
clotting factors that are dependent on vitamin K. This action decreases the ability of the
body to form blood clots. After its action, the medication is cleared through the cytochrome
P450 enzymes found in the liver (Carlquist et al., 2013). Heparin acts by binding different
proteins and enzymes thereby preventing fibrin and thrombin from working correctly in the
blood hence making the process of blood clotting and coagulation to stop. It is metabolized
through the liver and through endothelial system. It is eliminated by reticuloendothelial
system and small fractions excreted via urine.