Pharmacology: Anticoagulants and Antiplatelets Unit 6.2

Anticoagulants, Antiplatelets, and Thrombolytics

• Anticoagulants prevent clot formation.
• Antiplatelets prevent platelet aggregation.
• Thrombolytics dissolve existing clots.

Thrombus Formation - Pathophysiology

• Clots form in arteries or veins.
• Decreased circulation, vessel wall platelet aggregation, and blood coagulation cause clots.
• Arterial clots involve platelets.
• Fibrin formation traps red blood cells (RBCs) in clots.
• Venous clots involve platelet aggregation and fibrin attaching to RBCs.

Drugs Used to Maintain or Restore Circulation

• Antiplatelets: aspirin, clopidogrel
• Anticoagulants: warfarin, heparin, enoxaparin
• Thrombolytics: alteplase

Antiplatelet Drugs - Aspirin

• Effective and inexpensive for suppressing platelet aggregation.
• Low-dose therapy.
• Inhibits platelet aggregation by inhibiting COX 1.
• Use: Prevention of myocardial infarction (MI) and stroke.

Antiplatelets - Clopidogrel Bisulfate

• Action: Suppresses platelet aggregation.
• Used to prevent thrombosis in arteries, prevent myocardial infarction or stroke (especially in clients with a family history), prevent repeat myocardial infarction or stroke, and prevent stroke from transient ischemic attacks.

Side Effects/Adverse Reactions - Clopidogrel Bisulfate

• Abdominal pain
• Bleeding
• Hypotension

Contraindications - Clopidogrel Bisulfate

• Bleeding
• Peptic ulcer
• Liver disease
• Renal disease

Interactions - Clopidogrel Bisulfate

• Other drugs that cause bleeding (e.g., 5 G's: ginger, garlic, ginseng, ginkgo biloba, green tea)

Oral Anticoagulants - Warfarin

• Action: Inhibits hepatic synthesis of vitamin K, impacting clotting factors II, VII, IX, and X.
• Use: Prevents and treats blood clotting, used for treatment and prevention of deep vein thrombosis (DVT), pulmonary embolism, and stroke.
• Monitoring: PT and INR (2-3)

Side Effects/Adverse Reactions - Warfarin

• Gastrointestinal (GI) upset
• Bleeding

Vitamin K

• Antidote for warfarin overdose.
• Effective 24-48 hours after administration.
• For acute bleeding, fresh frozen plasma or platelets are administered.

Contraindications - Warfarin

• Blood dyscrasias
• Alcoholism
• Head trauma
• Diabetes mellitus

Interactions - Warfarin

• Other drugs/herbs causing bleeding.
• Medications increasing warfarin effect.
• Maintaining consistent vitamin K food intake.

Oral Anticoagulants - Apixaban

• Action: Selectively blocks clotting factor Xa to prevent clot formation.
• Use: Prevents and treats DVT and PE, preventing stroke and atrial fibrillation.
• Monitoring: Does not require routine coagulation monitoring.

Side Effects/Adverse Reactions - Apixaban

• Bleeding
• Hypotension

Contraindications - Apixaban

• Clients weighing less than 50 kg (increased risk of bleeding)

Interactions - Apixaban

• Other drugs/herbs causing bleeding.

Anticoagulants - Heparin

• Action: Inhibits thrombin, fibrinogen-to-fibrin conversion, and clot formation.
• Use: Prevents or treats venous thrombosis.
• Administration: Subcutaneous or intravenous.
• Monitoring: Frequent lab monitoring (PTT 1.5-2.5 times normal, aPTT 1.5-2.5 times normal).

Side Effects/Adverse Reactions - Heparin

• Bleeding
• Injection site irritation

Contraindications - Heparin

• Hemorrhagic stroke
• Bleeding issues
• Use caution in clients with peptic ulcer disease
• Interactions: Other drugs/herbs causing bleeding.

Anticoagulants - Enoxaparin

• Type: Low-molecular-weight heparin (LMWH).
• Action: Inactivates factor Xa.
• Use: Prevent DVT and PE after orthopedic or abdominal surgery.
• Precautions: Do not take aspirin concurrently or other drugs causing bleeding,
• Administration: Subcutaneous, once or twice daily.

Thrombolytics - Alteplase

• Action: Converts plasminogen to plasmin, degrading fibrin and other clotting factors, dissolving clots.
• Uses: Dissolves clots following acute MI, pulmonary embolism, ischemic stroke, and DVT; all end in -ase.

Side Effects/Adverse Reactions - Alteplase

• Anaphylaxis
• Hemorrhage

Contraindications - Alteplase

• Bleeding
• Recent surgery/trauma
• Severe liver dysfunction
• Head trauma
• Interactions: Other drugs/herbs causing bleeding (NSAIDs)

Nursing Process - Anticoagulants - Assessment

• Baseline vital signs
• Complete blood count (CBC), PT, INR, and PTT.
• Medical history
• Recent surgeries/trauma
• Time of event onset.
• History of blood thinners (including ibuprofen) and other drugs causing bleeding
• For thrombolytics, focus on recent surgeries/trauma, time of event onset.

Interventions - Anticoagulants

• Monitor vital signs.
• Monitor lab values (CBC, PT/INR for warfarin, PTT for heparin, all for alteplase).
• Monitor for bleeding; Use soft toothbrush, electric razor, etc.
• Have antidote available (heparin, warfarin).
• Monitor for allergic reactions.
• Avoid unnecessary venipunctures.

Teaching - Anticoagulants

• Signs/symptoms of bleeding to report.
• Use soft toothbrush, electric razor.
• Inform dentists about medications.
• Medic alert bracelet.
• Stop smoking.
• Avoid NSAIDs and other drugs, herbal products, that cause bleeding.
• Maintain consistent vitamin K intake for warfarin diet.

Practice Questions (and answers are implied from provided text)

• Detailed answers to all practice questions are provided in the document..