Anticoagulation for Dentistry Flashcards
Thrombosis
Types
Characteristics
Inappropriate blood coagulation within a vessel Arterial Fast flowing high pressure platelet rich
Venous
involves coagulation cascade
low pressure
fibrin rich
Appropriate blood coagulation occurs when
Failure
blood escapes from vessel
bleeding
Thrombosis treatment
Arterial
Venous
Anti platelet drugs
Anticoagulant drugs
Guidelines
Scottish Dental Clinical Effectiveness guideline Evidence based Up to date Freely available Printed advice for patients DOAC guideline less cautious
Anti platelet drugs - aspirin
Inhibits COX irreversibly
Acts for lifetime of platelet i.e 7-10 days
75-300mg/day
Anti platelet drugs - clopidogrel
Blocks ADP receptor (on platelet surface) irreversibly
Acts for lifetime of platelet i.e. 7-10 days
75mg/day
Anti platelet drugs - prasugrel
Blocks ADP receptor
irreversibly
blocks ALL platelets
Acts for lifetime of platelet i.e. 7-10 days
More rapid and consistent inhibition than clopidogrel
Anti platelet drugs and dental procedures
Balance risk of bleeding vs risk of thrombosis
Anti platelet medications do not have be stopped during PRIMARY care dental procedures
Anticoagulant drugs
Intravenous
Subcutaneous
Oral
Anticoagulant drugs - IV
Unfractionated heparin
Anticoagulant drugs - subcutaneous
Low molecular weight heparins e.g enoxaparin, tinzaparin, dalteparin
Anticoagulant drugs - oral
Warfarin, dabigatran, rivaroxaban, apixoban, edoxaban
Heparin Source Mechanism? Delivery Who to Monitored with?
Glycosaminoglycan from porcine mucosa
Binds to antithrombin and increases activity
Indirection thrombin inhibitor (as acts by enhancing activity of antithrombin)
Continuous infusion
Hospital patients
APTT test
Ratio of 1.8-2.8 desired
Low molecular weight heparin
structure?
Delivery
Excretion and frequency of delivery
Used for
Timings
Smaller molecule from unfractionated heparin SC Really excreted given once daily no monitoring
Treatment and prophylaxis
Give last dose 24 hours before dental surgery
Half life of 12 hrs
Next dose 4 hrs after dental surgery
Warfarin - pharmacology
Delivery
Bound to
Mechanism?
Given orally
99% plasma protein bound
Inhibits production of factors II, VII, IX, X and protein C and S
Metabolised by liver (cytochrome P450)
Has peak effect 3-4 days after start - residual factors have to be used up
Effect still present 4- days after stopping
Warfarin interactions
Potentiation of anticoagulation
Inhibition of anticoagulation
Warfarin - Potentiation of anticoagulation
Reduced warfarin binding to albumin e.g by phenytoin
Inhibition of hepatic microsomal degradation of warfarin e.g by erythromycin
Warfarin interactions - inhibition of anticoagulation
Acceleration of hepatic microsomal degradation of warfarin e.g by carbamazepine
Enhanced synthesis of clotting factors e.g by vitamin K
Warfarin monitoring
Test
Dose based on
FREQUENCY DEPENDS ON
International normalised ratio
INR
Stability of INR e.g 1/week 1-8 weeks
Must be measured before surgery or invasive procedures
Measured using near patient testing device
Uses drop of blood
Anticoag INR targets
INR 2-3 - treatment of DVT , atrial fibrillation - 2 = 2x long for blood to clot
INR 3-4.5 e.g recurrent DVT on warfarin
Mechanical heart valves
Warfarin side effects
Annual risk
3% bleeding 1% serious 0.3% death due to bleeding Skin necrosis Embryopathy
Warfarin reversal options
Stop warfarin
Vitamin K - IV preparation, 80% correction
Fresh frozen plasma - large vole
Clotting factor concentrate -
Clotting factor concentrate -
Factors II, VII, IX, X - IN 10 MINS
Warfarin warnings
No IM injections No aspirin, NSAID without consultation No contact sports m moderate alcohol signify changes in diet
Dental extractions and warfarin
Lower risk nowadays of thrombotic episode
Safe to perform X-LA on warfarin when
Metal heart valve patients will
INR < 4.0
Remain on warfarin
New non warfarin oral anticoagulants
NOACS -new oral anticoagulants
DOACS
RIVAROXABAN, PIXABAN, ADOXABAN
DABIGATRAN A
Inhibit Fx Xa
inhibits thrombin factor ii
may replace low molecular weight heparin for prophylaxis
also treats thrombosis and AF
DOACs
Prevention and treatment of thrombosis Replacing warfarin No monitoring No alcohol/food interactions Half life 6-15 hrs Dabigattran is mainly recalled excreted
DOACs in dental surgery
Use vasoconstrictor in LA
Use infiltration if poss
Delay work until discontinuation if short term
Do not take anticoag on morning of work Restart 4hrs post procedure
APIXABAN/DABIGATRAN
2x a day
Miss morning dose pre treatment
Given at usual time in evening
Rivaroxaban
once a day
delay morning dose pre treatment for later effect
resume 4hrs after haemostasis
Partially really excreted
Edoxaban
Once a day - evening
Doesn’t need to delay in morning
Resume at usual time
