Haematological system Flashcards
Anticoagulation: What is thrombosis?
Inappropriate blood coagulation within a vessel is called thrombosis
Anticoagulation: What is appropriate blood coagulation?
when blood escapes from a vessel (failure of this results in bleeding)
Anticoagulation: What are the two types of coagulation?
In the arterial circulation:
high pressure system
platelet rich
In the venous circulation:
low pressure system
fibrin rich
Anticoagulation: How is arterial thrombosis treated?
Antiplatelet
Anticoagulation: How is venous thrombosis treated?
Anticoagulant
Anticoagulation: What are 3 common anti platelet drugs? How do they work? What is the lifetime of the drug? What is the dose?
Aspirin
Inhibits cyclo-oxygenase (platelet enzyme) irreversibly
Act for lifetime of platelet ie 7-10 days
Dose 75-300mg per day
Clopidogrel
Blocks ADP receptor (on platelet surface) irreversibly
Acts for lifetime of platelet ie 7-10 days
Dose 75mg per day
Prasugrel
Blocks ADP receptor irreversibly
Acts for lifetime of platelet ie 7-10days
More rapid and consistent inhibition than clopidogrel
Anticoagulation: What type of medication does not have to be stopped before dental procedures?
Antiplatelet
Anticoagulation: What are the common anticoagulants and via what route are they taken?
Intravenous
Unfractionated heparin
Subcutaneous
Low molecular weight heparins eg enoxaparin, tinzaparin, dalteparin
Oral
Warfarin, dabigatran, rivaroxaban, apixaban, edoxaban
Anticoagulation: What does heparin bind to?
Antithrombin which increases the activity of antithrombin
it’s an indirect thrombin inhibitor as it enhances the activity of antithrombin
Anticoagulation: How is heparin given in hospital and monitored?
continuous infusion
APTT test - aim for ratio 1.8-2.8
Anticoagulation: What is low molecular weight heparin and how is it given? What is it used for?
Smaller molecule made from unfractionated heparin Given subcutaneously Renally excreted Given once daily. Weight adjusted dosing No monitoring necessary
Used for treatment and prophylaxis
In Sheffield – Dalteparin is used
Anticoagulation: When is low molecular weight heparin stopped and started after dental treatment?
For dental work give last dose 24 hours before dental surgery
Next dose 4 hours after dental surgery
Anticoagulation: What does warfarin inhibit?
factors II, VII, IX, X - 2, 7, 9, 10 (vitamin K dependent)
protein C and protein S
Anticoagulation: Where is warfarin metabolised?
the liver via cytochrome P450
Anticoagulation: When do the effects of warfarin start and continue after being stopped?
Peak effect 3-4 days after starting, and effect still present 4-5 days after stopping
ie slow on and slow off action
Anticoagulation: What drug may reduce warfarin binding to albumin?
phenytoin
Anticoagulation: What drug may inhibit hepatic microsomal degradation of warfarin?
Erythromycin - strong interaction, stays in blood stream longer - cerebral bleed