W14 49 anticoagulants, steroids, insulin Flashcards
What drugs affect clotting?
Aspirin
Clopidogrel
Heparins
Warfarin
Non-vitamin K oral anticoagulants (NOACs)
Thrombolytics (not used much anymore’
What are the problems with anticoagulants for dentists?
- excessive bleeding after oral or periodontal surgery
- modification of regimen might predispose patients to thromboembolic events
- danger of drug interactions
Assess benefit vs harm = clot vs bleed balance
What considerations are there for bleeding risk?
High vs low risk of bleeding from treatment
Lifelong or limited treatment
Bleeding history
What effect does aspirin have?
Antiplatelet effect. Lasts 7-10 days (life of a platelet)
What mechanism does aspirin work by?
Irreversible cyclo-oxygenate (COX) inhibition. Prevents thromboxane A2 production.
What are the uses of aspirin and usual dose?
Uses - stroke, TIA, ischaemic heart/peripheral vascular disease
Dose - 75mg (baby aspirin) to 300mg daily
What are the problems with taking aspirin in dental patients?
Increased bleeding time
Problems of oozing from sockets
May require increased local haemostatic measures
What other Antiplatelet drugs are there?
Clopidogrel, dipyridamole, prasugrel and ticagrelor
What does clopidogrel do?
Selectively inhibits ADP-induced platelet aggregation (by PY12 receptor inhibition)
What does stopping Antiplatelet mono therapy do?
Stopping anti-platelet therapy increases the risk of stroke or MI (especially if recent coronary stent). Patients are more at risk of permanent disability or death if Rc stopped prior to a procedure than if they continue it. Bleeding complications are inconvenient but not as risky to life.
What should you do for patients on anti-platelet dual therapy?
Treatment with aspirin and clopidogrel increases bleeding time more than either alone. Might need to consult with cardiologist and treat at hospital-based clinic, potentially will say to go back on aspirin only for a little bit.
What are heparins?
Not oral anticoagulants
What does unfractionated heparin do? Describe its effects and when to use it. (RARELY USED!)
Inactivates multiple coagulation factors. Used IV or subcutaneously.
Can be used prophylactically to stop patients getting clots in the perioperative period.
Invasive dental procedures should be avoided during active treatment
Used infrequently compared with LMWH except in dialysis patients
Short t1/2 effects last a few hours
Procedures safe 12-24hrs after last administration
What are LMWH and give some example?
Low molecular weight heparins eg enoxaparin, dalteparin
What do LMWH do?
Inhibits activated factor X (Xa)
When are LMWH used and can you do dental procedures during treatment?
Used subcutaneously for prophylaxis of DVT and treatment of acute coronary syndromes and DVT/PE
Longer t1/2 - effects last upto 24hrs
Procedures safe with prophylactic doses
High (treatment) doses can usually be stopped for one day the day before surgery then resumed post-op following haemostasis.
What is warfarin and what does it do?
Vitamin K antagonist - inhibits vitamin K dependent clotting factors (2,7,9,10)
Increases clotting times (increases PT and INR)
What is the half life of warfarin?
3 days - so if stopped can still have prolonged clotting time for days after treatment
What is warfarin used for?
DVT/PE, atrial fibrillation, metallic heart valves etc
How is warfarin monitored?
INR (internationalised normalised ratio)
INR = prothrombin time / standard prothrombin time
What should the target INR’s be?
2.0-3.0 (average 2.5) for: treatment of DVT or PE, valvular heart disease, atrial fibrillation
3.0-4.0 (average 3.5) for: mechanical prosthetic heart valves
What does it mean if you have a higher INR?
The higher the INR, the more thinned the blood and the harder it is to clot.
What are the adverse effects of warfarin?
Bleeding (from anywhere!)
Skin rashes
Slope is
Diarrhoea, skin necrosis, jaundice
Bleeding peptic ulcer (from taking NSAIDs and warfarin eg)
Subconjuctival haemorrhage