6. Antiplatelet And Fibrinolytic Drugs Flashcards
Which drugs are used in platelet rich ‘white’ arterial thrombi?
Antiplatelet and fibrinolytic drugs
Which drugs are used in lower platelet content, ‘red’ venous thrombi?
Parenteral anticoagulants and oral anticoagulants
Name a cyclo-oxygenase inhibitor
Aspirin
What is the action of cyclo-oxygenate inhibitors?
Inhibits COX-1 mediated production of TXA2 and reduces platelet aggregation - irreversible
What are the adverse affects of aspirin?
GI irritation, GI bleeding, haemorrhage, hypersensitivity
What are the contraindications of aspirin?
Reye’s syndrome - avoid <16 years Hypersensitivity 3rd trimester (premature closure of ductus arteriosus)
What are the important drug interactions with aspirin?
Other antiplatelet and anticoagulants
What are some indications of aspirin?
Antithrombotic
Atrial fibrillation
Secondary retention of stroke and TIA
Secondary prevention of acute coronary syndromes
Often co prescribed with other antiplatelet drugs
NSTEMI/STEMI
Acute ischaemic stroke
What is required in long term use of aspirin?
Gastric protection - proton pump inhibitor
Name some ADP receptor antagonists
Clopidogrel
Prasugrel
Ticagrelor
What is the action of ADP receptor antagonists?
Inhibit dining of ADP to P2Y12 receptor, therefore inhibiting activation of GPIIb/IIIa receptors
Which ADP receptor antagonists have slow onset of action and which have fast?
Clopidogrel has slow onset of action without a loading dose
Ticagrelor and prasugrel have a more rapid onset of action
What are the adverse effects of ADP receptor antagonists?
Bleeding
GI upset - dyspepsia, diarrhoea
Rarely thrombocytopenia
What are the contraindications of ADP receptor antagonists?
Caution in high bleed risk patients with renal and hepatic impairment
What are the important drug reactions wit ADP receptor antagonists?
Clopidogrel requires CYPs for activation therefore:
- CYP inhibitors (omeprazole, ciprofloxacin, erythromycin, some SSRIs
Ticagrelor can interact with CYP inhibitors and inducers
Caution when co prescribed with other antiplatelet and anticoagulant agents or NSAIDs
When would clopidogrel need to be stopped?
7 days prior to surgery
When are ADP receptor antagonists used?
Clopidogrel as mono therapy when aspirin is contraindicated
NSTEMI patients up to 3 months
STEMI patients up to 4 weeks
Ischaemic stroke and TIA long term secondary prevention
Name a phosphodiesterase inhibitor
Dipyridamole
What is the action of phosphodiesterase inhibitors?
Dipyridamole inhibits cellular reuptake of adenosine, this increases [adenosine], which inhibits platelet aggregation via adenosine receptors
Also prevents cAMP degradation which inhibits expression of GPIIb/IIIa
What are the adverse effects of phosphodiesterase inhibitors?
V and D
Dizziness
What are the important drug reactions with phosphodiesterase inhibitors?
Antiplatelets and anticoagulants, adenosine
When are phosphodiesterase inhibitors used?
Antiplatelet
Secondary prevention of ischaemic stroke and TIAs
Adjunct for prophylaxis of thromboembolism following valve replacement
Stroke
Give an example of glycoprotein IIb/IIIa inhibitors
Abciximab
What is the action of glycoproteins IIb/IIIa inhibitors?
Blocks binding of fibrinogen and vWF
Target final common pathway leading to more complete platelet aggregation
What are the adverse effects of glycoprotein IIb/IIIa inhibitors?
Bleeding
What are the important drug interactions with abciximab?
Caution with other antiplatelet and anticoagulant agents
When is abciximab used?
Specialist use in high risk percutaneous transluminal coronary angioplasty patients with other drugs
How do fibrinolytic agents work?
Dissolve the fibrin mesh work of thrombus
What are the adverse effects of fibrinolytic agents?
Bleeding
What are the important drug reactions with fibrinolytic agents?
Antiplatelets and anticoagulants
What are some fibrinolytic agents?
Streptokinase
Alteplase
Tranexamic acid - stops bleeding
Why can streptokinase not be used more than once?
Antibodies develop
