Anticoagulation for Dentistry

Question 1

Thrombosis
Types
Characteristics

Answer 1

Inappropriate blood coagulation within a vessel 
Arterial
Fast flowing
high pressure 
platelet rich

Venous
involves coagulation cascade
low pressure
fibrin rich

Question 2

Appropriate blood coagulation occurs when

Failure

Answer 2

blood escapes from vessel

bleeding

Question 3

Thrombosis treatment
Arterial
Venous

Answer 3

Anti platelet drugs

Anticoagulant drugs

Question 4

Guidelines

Answer 4

Scottish Dental Clinical Effectiveness guideline 
Evidence based
Up to date 
Freely available 
Printed advice for patients 
DOAC guideline less cautious

Question 5

Anti platelet drugs - aspirin

Answer 5

Inhibits COX irreversibly
Acts for lifetime of platelet i.e 7-10 days
75-300mg/day

Question 6

Anti platelet drugs - clopidogrel

Answer 6

Blocks ADP receptor (on platelet surface) irreversibly
Acts for lifetime of platelet i.e. 7-10 days
75mg/day

Question 7

Anti platelet drugs - prasugrel

Answer 7

Blocks ADP receptor
irreversibly
blocks ALL platelets
Acts for lifetime of platelet i.e. 7-10 days
More rapid and consistent inhibition than clopidogrel

Question 8

Anti platelet drugs and dental procedures

Answer 8

Balance risk of bleeding vs risk of thrombosis

Anti platelet medications do not have be stopped during PRIMARY care dental procedures

Question 9

Anticoagulant drugs

Answer 9

Intravenous
Subcutaneous
Oral

Question 10

Anticoagulant drugs - IV

Answer 10

Unfractionated heparin

Question 11

Anticoagulant drugs - subcutaneous

Answer 11

Low molecular weight heparins e.g enoxaparin, tinzaparin, dalteparin

Question 12

Anticoagulant drugs - oral

Answer 12

Warfarin, dabigatran, rivaroxaban, apixoban, edoxaban

Question 13

Heparin 
Source
Mechanism? 
Delivery 
Who to
Monitored with?

Answer 13

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

Question 14

Low molecular weight heparin

structure?
Delivery
Excretion and frequency of delivery

Used for

Timings

Answer 14

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

Question 15

Warfarin - pharmacology
Delivery
Bound to
Mechanism?

Answer 15

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

Question 16

Warfarin interactions

Answer 16

Potentiation of anticoagulation

Inhibition of anticoagulation

Question 17

Warfarin - Potentiation of anticoagulation

Answer 17

Reduced warfarin binding to albumin e.g by phenytoin

Inhibition of hepatic microsomal degradation of warfarin e.g by erythromycin

Question 18

Warfarin interactions - inhibition of anticoagulation

Answer 18

Acceleration of hepatic microsomal degradation of warfarin e.g by carbamazepine
Enhanced synthesis of clotting factors e.g by vitamin K

Question 19

Warfarin monitoring
Test
Dose based on
FREQUENCY DEPENDS ON

Answer 19

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

Question 20

Anticoag INR targets

Answer 20

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

Question 21

Warfarin side effects

Annual risk

Answer 21

3% bleeding 
1% serious
0.3% death due to bleeding 
Skin necrosis 
Embryopathy

Question 22

Warfarin reversal options

Answer 22

Stop warfarin
Vitamin K - IV preparation, 80% correction
Fresh frozen plasma - large vole
Clotting factor concentrate -

Question 23

Clotting factor concentrate -

Answer 23

Factors II, VII, IX, X - IN 10 MINS

Question 24

Warfarin warnings

Answer 24

No IM injections 
No aspirin, NSAID without consultation 
No contact sports m
moderate alcohol
signify changes in diet

Question 25

Dental extractions and warfarin

Answer 25

Lower risk nowadays of thrombotic episode

Question 26

Safe to perform X-LA on warfarin when

Metal heart valve patients will

Answer 26

INR < 4.0

Remain on warfarin

Question 27

New non warfarin oral anticoagulants

Answer 27

NOACS -new oral anticoagulants

DOACS

Question 28

RIVAROXABAN, PIXABAN, ADOXABAN

DABIGATRAN A

Answer 28

Inhibit Fx Xa
inhibits thrombin factor ii

may replace low molecular weight heparin for prophylaxis
also treats thrombosis and AF

Question 29

DOACs

Answer 29

Prevention and treatment of thrombosis 
Replacing warfarin 
No monitoring 
No alcohol/food interactions 
Half life 6-15
 hrs 
Dabigattran is mainly recalled excreted

Question 30

DOACs in dental surgery

Answer 30

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

Question 31

APIXABAN/DABIGATRAN

Answer 31

2x a day
Miss morning dose pre treatment
Given at usual time in evening

Question 32

Rivaroxaban

Answer 32

once a day
delay morning dose pre treatment for later effect
resume 4hrs after haemostasis
Partially really excreted

Question 33

Edoxaban

Answer 33

Once a day - evening
Doesn’t need to delay in morning
Resume at usual time