Anticoagulation for dentists - Haematological disorders Flashcards
What do to regarding dental procedures when the pt is on antiplatelets?
Balance risk of bleeding vs risk of thrombosis if drugs are discontinued
Antiplatelets do NOT have to be stopped before primary care dental surgical procedures
List the intravenous, subcutaneous and oral anticoagulants
Intravenous = unfractionated heparin
Subcutaneous = low molecular weight heparins e.g. enoxaparin, tinzaparin, delteparin
Oral = warfarin, dabigatran, rivaroxaban, apixaban, edoxaban
How does prasugrel work?
Blocks ADP receptor irreversibly
Acts for lifetime of platelet 7-10days
More rapid and consistent inhibition than clopidogrel
What is heparin?
How does it work?
Glycoseaminoglycan derived from porcine mucosa
Binds to antithrombin and increases its activity
Indirect thrombin inhibitor
Given by continuous infusion - hospital pts only
How to monitor heparin?
Monitor with APTT test - aim for ratio 1.8-2.8
What is low molecular weight heparin?
Smaller molecule made from unfractionated heparin
How is low molecular weight heparin given?
Given subcutaneously and renally excreted
Once daily - weight adjusted dosing
No monitoring necessary
Low molecular weight heparin and dentistry?
For dental work give last dose 24hrs before dental surgery
Next dose 4hrs after dental surgery
How is warfarin given?
By mouth and rapidly absorbed
What does warfarin do?
Inhibits production of:
Factors II, VII, IX, X
Protein C and protein S
Metabolised by the liver via cytochrome P450
Peak effect 3-4 days after starting
Effect present 4-5 days after stopping
What drugs do warfarin interact with?
Potentiation of anticoagulation:
- Reduced warfarin binding to albumin
e. g. Phenytoin - Inhibition of hepatic microsomal degradation of warfarin
e. g. Erythromycin
Inhibition of anticoagulation:
- Acceleration of hepatic microsomal degradation of warfarin
e. g. Carbamazepine - Enhanced synthesis of clotting factors e.g. vitamin K
How to monitor warfarin?
INR
Dose of warfarin depends of INR
Frequency of monitoring depends on stability of INR
Measure before surgery or invasive procedure
When is the INR of 2-3 a target?
Treatment of DVT/PE (6 months) Atrial fibrillation (life-long)
When is the INR of 3-4.5 a target?
Recurrent DVT/PE on warfarin
Mechanical heart valves
Side effects of warfarin?
3% any bleeding 1% serious/life threatening 0.3% death due to bleeding Skin necrosis Embryopathy (if used in 1st trimester of pregnancy)
How to reverse warfarin?
Stop warfarin - takes 2-3 days Vitamin K - 80% correction in 6hrs Fresh frozen plasma - only partial correction Clotting factor concentrate - Containing factors II, VII, IX, X - Complete correction in 10 mins
What to warn pts on warfarin?
No IM injections
No aspirin, NSAID without consultation
No contact sports
Excessive alcohol intake is harmful
Significant changes in diet should be reported
Consult doctor or pharmacist before any new meds including OTC
Evidence of issues with dental extractions when on warfarin?
Wahl 1998 - 12 episodes of serious bleeding
When is it safe to extract teeth when on warfarin?
INR less than 4
Check INR within 24hrs of extraction
Name the new oral anticoagulants
NOACs
DOACs
- Rivaroxaban, apixaban, edoxaban (Xa inhibitors)
Dabigatran (thrombin inhibitor)
Pros of DOACs
Standard oral doses No alcohol or food interactions Fewer drug interactions No major adverse events other than bleeding Half life 6-15hrs
Negatives of DOACs
No antidote
More expensive than warfarin
DOAC and dental surgery?
Use LA with vasoconstrictor
Use infiltration or intraligamentary injection
If IAN used - inject slowing with aspiration
If on short term anticoagulation treatment = delay dental work until not on meds if possible
Do not take anticoagulant on morning of dental work
Restart 4hrs post prcedure
Taking apixaban, dabigatran, rivaroxaban and edoxaban before and after dental surgery?
Apixaban or dabigatran = miss morning dose, post treatment usual time in evening as long as at least 4hrs after haemostasis
Rivaroxaban = delay morning dose, evening = 4hrs after haemostasis Edoxaban = not applicable in morning, usual time in evening if 4hrs after haemostasis
