Chapter 28 Coagulation Modifier Drugs

Question 1

Anticoagulants

Answer 1

• Prevent formation of intravascular clot by inhibiting certain clotting factors. Also prevent extension of a preformed clot/thrombus. No direct effect on existing clots or on ischemic injured tissue
• Also called antithrombotic drugs
• Indications: Prevent clot formation for circumstance that may lead to stroke, heart attack, pulmonary embolism, DVT
• Protamine sulfate to reverse anticoagulation
• Adverse effects include: increased bleeding, bleeding gums, bruising, melena (blood in the feces)
• Teach patients about bleeding risk and activity limitations (how to shave)

Question 2

Heparin

Answer 2

• Heparin binds to antithrombin III (AT-III) to shut off:
  Thrombin is the most sensitive to the actions of heparin
• Also used (both heparin & LMWs) as bridge therapy when a patient stops warfarin for surgery or other invasive procedures

Question 3

Low Molecular Weight Heparins

Answer 3

• Much more specific to inhibiting factor X(Xa) than Thrombin
• Results in more predictable anticoagulant response
• Implication: Less lab monitoring so patients can use this therapy safely at home and come in less often for (aPTTs)
• Enoxaparin sodium

Question 4

Warfarin (Coumadin)

Answer 4

• Inhibit Vitamin K synthesis by GI bacteria and results in inhibition of the production of vitamin K dependent clotting factors II, VII, IX, and X
• Vitamin K conversely used to reverse warfarin effects to hasten normal coagulation in the event of complications (excessive bleeding)
• Long term home use (oral route)
• Contraindicated in pregnancy
• Lab tests include INR and PT
• Interactions: furosemide, aspirin, carbemazepine, erythromycin

Question 5

Aspirin

Answer 5

• Inhibits cyclooxygenase in the platelet which prevents TXA2 (TXA2 causes platelet aggregation and vasoconstriction)
• Resultant effect of dilation, platelet aggregation and prevention of clot formation
• May affect vitamin K dependent clotting factors
• Used for stroke prevention (you have seen low dose therapy of 81mg daily)

Question 6

Clopidogrel (Plavix)

Answer 6

• most commonly used ADP inhibitor
• Alters platelet membrane so that it can no longer receive signal to aggregate and form plug
• Shown to be better than aspirin at reducing number of MI’s, strokes and vascular deaths for at-risk patients
  Used for stroke prevention plus preventing TIAs and post MI thrombotic prevention

Question 7

Eptifibatide (Integrilin)

Answer 7

• GP II/IIIa inhibitor
• Newest class of antiplatelet drugs so good to keep in mind
• Block the receptor protein in the platelet membrane
• Used to treat acute unstable angina, MI and during PCI (pericoronary interventions such as angioplasty)

Question 8

Antiplatlets

Answer 8

• Interactions: NSAIDs increased effect, Dipyyridamole increased effect, and enhances effects of oral hypoglycemics (especially large doses of aspirin)
• Adverse effects include: diarrhea, dizziness, bleeding, nausea

Question 9

Thrombolytics

Answer 9

• Activation of the thrombolytic system to actually dissolve clots. Mimic the body’s own process of clot destruction via activating plasmin (breaks down proteins such as fibrin, fibrinogen)
• New thrombolytics have specificity for fibrin and work primarily at the site of the clot
• Resultant effect: re-established venous and/or arterial bloodflow. Minimize tissue injury from ischemia
• Contraindicated with concurrent use of other coagulation modifier drugs
• Adverse effects include internal, intracranial and superficial bleeding
• Relatively short half-life and no specific antidotes
• Inreased bleeding tendency with concurrent use of anticoagulants, antiplatlets, or other drugs that affect platelet functions
• Alteplase (Activase)
• Streptokinase (Streptase)