Chapter 19
Agents Affecting
Blood Clotting
Anticoagulants
 Inhibit
the action or formation of one
or more clotting factors
 Heparin-potent inhibitor of the clotting
process
 Used in the prophylaxis and treatment
of clotting disorders
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Anticoagulants
 Heparin
Indirectly
interferes with the conversion
of prothrombin to thrombin
The deficiency of thrombin prevents the
conversion of fibrinogen to fibrin
Inhibits the formation of clots
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Anticoagulants
 Heparin
Given
subcutaneously of intravenously
(continuous infusion)
Rapid and predictable action
First drug used in anticoagulant therapy
Patient changed to an oral anticoagulant
when a desired prothrombin time is
achieved
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Anticoagulants
 Adverse
effects
subcutaneous
bleeding
blood in the stool, hematuria
bleeding gums
nosebleeds
bruising
hypersensitivity
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Anticoagulants
 Treatment
of overdose
1% protamine sulfate
Inactivates heparin
Slow infusion
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Anticoagulants
 Many
drug-drug and drug-herb
interactions to heparin that increase
bleeding and delay clotting time
 Many drug-drug and drug-herb
interactions that decrease the effect
of heparin
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Anticoagulants
 Lovenox
Low
molecular weight heparin
anticoagulant
Only given subcutaneously
Prophylaxis and treatment of DVT
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Anticoagulants
 Adverse
effects
bleeding
gums
nose bleeds
bruising
hematuria
blood in stool
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Oral Anticoagulants
 Inhibits
blood clotting by interfering
with the synthesis of vitamin Kdependent clotting factors in the
liver
 Action is not evident for 12-24 hours
after the first dose
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Oral Anticoagulants
 warfarin
(Coumadin)
More predictable action
 lower incidence of adverse effects
Close monitoring of the patient
Dosages are individualized and
dependant on INR
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Oral Anticoagulants
 warfarin
(Coumadin)
therapeutic INR 2-3
Many drug-drug and drug-herb
interactions
Overdosage: Vitamin K
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Antiplatelet Agents
 clopidogrel
(Plavix)
Inhibit the aggregation of platelets
Patients following a CVA or MI
May help prevent recurrence
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Antiplatelet Agents
 Patients
should avoid using
medications that contain aspirin
 Avoid using non-steroidal antiinflammatory drugs
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Antiplatelet Agents
 clopidogrel
(Plavix)
Adverse effects
 dizziness
 nose
bleeds
 GI bleeding
 bleeding
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Thrombolytic Agents
 Enzyme
that dissolves fibrin clots
 Indicated for the lysis of pulmonary
emboli and for clearing clots from
central venous catheters
streptokinase
urokinase
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Thrombolytic Agents
 urokinase
Drug
of choice for clearing central
venous catheters
Patients should be monitored for
bleeding
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