chapter 52- anticoagulant, antiplatelet Flashcards
Anticoagulant drugs
Heparin and warfarin
- the reduce formation of fibrinogen
- All anticoagulants interfere with some point in the coagulation cascade
- These agents can be given parenterally or orally
- Anticoagulants are indicated for both treatment and prophylaxis of thromboembolism
Unfractionated Heparin (UFH) mechanism of action
Antithrombin III undergoes a conformational change that enhances its binding capability
- Heparin has a rapid onset of action. Anticoagulant effects begin as soon as heparin starts binding to antithrombin III.
what does Unfractionated Heparin (UFH) binds to
UFH binds to factor IIa (thrombin) and factor Xa
Unfractionated Heparin (UFH) indications
- Treatment of venous thromboembolism (VTE)
- Prophylaxis of VTE
- Myocardial infarction
- Atrial fibrillation
Unfractionated Heparin adverse effects
- Hemorrhage
- Spinal/epidural hematoma
- Heparin-induced thrombocytopenia (HIT)
Unfractionated Heparin laboratory monitoring
- Activated partial thromboplastin time (aPTT)
- Anti-factor Xa Assay
Reversal of Unfractionated Heparin
Protamine
Administration of protamine
- SLOW IV push
- Rapid administration will cause hypotension
low molecular weigh heparins (LMWH)
Enoxaparin
Dalteparin
low molecular weigh heparins (LMWH) indications
- Prevention of deep vein thrombosis (DVT)
- Treatment of venous thromboembolism (VTE)
- Treatment of myocardial infarction (MI)
pharmokinetics of low molecular weigh heparins (LMWH)
Renally excreted
- Doses must be reduced in renal impairment
low molecular weigh heparins (LMWH) adverse effects
- Hemorrhage
- Spinal/epidural hematoma
- Heparin-induced thrombocytopenia
low molecular weigh heparins (LMWH) monitoring points
not required
Fondaparinux mechanism of action
Pentasacchride binds to antithrombin and causes conformational change
what does Fondaparinux bind to
ONLY binds to factor Xa
Indications of fondaparinux
- Prophylaxis of DVT
- Treatment of VTE
fondaparinux monitoring points
No laboratory monitoring required
adverse effects of fondaparinux
- Hemorrhage
- Spinal/epidural hematoma
- NO risk of HIT
Warfarin Mechanism of Action
Decreases production of clotting factors Seven, Nine, Ten and Two (SNTT)
vitamin K antagonist
warfarin
indications of warfarin
- atrial fibrillation
- mechanical heart valves
- VTE
monitoring points for warfarin
International Normalized Ratio (INR)
pharmacokinetics of warfarin
Full effects in 3 to 5 days
dietary interactions of warfarin
- Vitamin K from diet can ↓ effectiveness of warfarin
- Keep intake of high vitamin K foods consistent
- If vitamin K intake ↑, then warfarin doses need to be ↑
- If vitamin K intake ↓, then warfarin doses need to be ↓
Examples of vitamin K rich foods:
- Mayonnaise
- Green leafy vegetables (spinach, kale)
- Soybean oil
reversal of warfarin effects
- Vitamin K (phytonadione)
- Must also administer fresh frozen plasma (FFP) in life-threatening bleeds
Direct Thrombin Inhibitors (DTI)
Dabigatran (PO)
Bivalirudin (IV)
Argatroban (IV)
Direct Thrombin Inhibitors (DTI) mechanism of action
Bind to and inhibit factor IIa (thrombin)
- NO need for laboratory monitoring with oral medications
adverse effect of Dabigatran
Dyspepsia
monitoring/counseling points of dabigatran
- No laboratory monitoring
- Educate on signs/symptoms of bleeding
- Reversal: Idarucizumab (Praxbind)
Factor Xa Inhibitors
- Rivaroxaban
- Apixaban
monitoring points for Factor Xa Inhibitors
No laboratory monitoring required
Rivaroxaban monitoring points
Take with food
reversal of rivaroxaban and apixaban
Adexanet-alfa
three main groups of Antiplatelet Drugs
- Aspirin
- P2Y12 ADP inhibitors
- GIIb/IIIa inhibitors
aspirin mechanism of action
- Irreversible inhibitor of COX-1 and COX-2
- Prevents production of thromboxane A2 (TXA2)
- TXA2 can promote platelet aggregation
adverse effects of aspirin
GI bleeding and ulcers
indication of aspirin
- Transient ischemic attack (TIA)
- Ischemic stroke
- Acute coronary syndrome
drugs of P2Y12 Adenosine Diphosphate Receptor Antagonists
- Clopidogrel (irreversible inhibitor)
- Prasugrel (irreversible inhibitor)
- Ticagrelor (reversible inhibitor)
ALL ORAL
Clopidogrel monitoring/counseling points
- clopidogrel is a prodrug
- Possible DDI with omeprazole because omeprazole inhibits CYP2C19
Ticagrelor
adverse effects
dyspnea
Glycoprotein IIb/IIIa Receptor Antagonists drugs
- Tirofiban
- Eptifibatide
- Abciximab
Mechanism of action Glycoprotein IIb/IIIa Receptor Antagonists
Reversible blockade of GIIb/IIIa receptors
Glycoprotein IIb/IIIa Receptor Antagonists indications
- acute coronary syndromes (ACS) and undergoing PCI
- Typically only used in the cath lab
Glycoprotein IIb/IIIa Receptor Antagonists are used in combination with?
they are used in combination with heparin during PCI
Thrombolytic (Fibrinolytic) Drugs
- Alteplase (MOST COMMON)
- Tenecteplase
adverse effects of Thrombolytic (Fibrinolytic) Drugs
high risk of bleeding
‘Clot-busting’ drugs
Thrombolytic (Fibrinolytic) Drugs
- Alteplase
- Tenecteplase
when are Thrombolytic (Fibrinolytic) Drugs used
Only used acutely for severe thrombus:
- Ischemic stroke
- Myocardial infarction
- Pulmonary embolism
another name for altepase
- tissue plasminogen activator (tPA)
indications of Alteplase
- Acute ischemic stroke
- Acute myocardial infarction
- Acute pulmonary embolism
Time is issue with alteplase
give these medications as quickly as possible!
adverse effects of alteplase
- Bleeding
- Angioedema
Methods to lower bleeding risk for alteplase
- Avoid SQ or IM injections during administration
- Minimize invasive procedures
- Minimize concurrent use of anticoagulants or antiplatelet drugs
