NOACS

Question 1

How are NOACs excreted?

Answer 1

Renally
Rivaroxaban is METABOLISED by the liver though, so moderate to severe impairment may incrase levels

Cutoff is less than 25 cr cl for apixaban and 30 ml/min for the others.

Question 2

MOA Dabigatran

Answer 2

Direct thrombin inhibition

Question 3

t1/2 Dabigatran

Answer 3

12-17 hours

Question 4

Which NAOC do you have to be careful of CYP 3A4 inducers/inhibitors?

Answer 4

Rivaroxaban

Question 5

For which NOAC are p glycoprotein inhibitors (eg verapamil) particuarly relevant?

Answer 5

Dabigatran

Question 6

Can you give the NOACs in pregnancy and breastfeeding?

Answer 6

No

Question 7

Dabigatran: most sensitive test for determining if present

Answer 7

Thrombin time

• Normal TT will exclude presence
• Normal APTT suggests unlikely that a high level is contributing to bleeding

No Chromogenic Xa assay
Can check the dilute thrombin clotting time assay - prolonged in confirmatory test

If APTT prolonged, exclude heparin and low fibrinogen

Question 8

Rivaroxaban: most sensitive coagulation assay

Answer 8

PT- normal suggests not high but does not exclude presence
APTT and PT cannot estimate intensity of anticoagulant effect
Does NOT prolong TT
APTT is prolonged dose dependently but is less sensitive than PT

Specific anti-factor Xa chromogenic assay for quantitative measurement - not the regular anti Xa assay

If PT prolonged, exclude warfarin and liver disease

Question 9

Apixaban: most sensitive coagulation assay

Answer 9

Need anti-factor Xa chromogenic assay to estimate accurately
Normal PT and APTT does NOT rule out significant anticoagulant effect- but unlikely if PT is normal

Question 10

How long should you stop the NOAC before an epidural goes in? After it goes in?

Answer 10

24 hours for all three
After it is in, don’t give dabigatran at all. 22-26 hours for rivarox and 26-30 hours for apixaban
After removal, wait 6 hours for all three before next dose.

Question 11

Dialysis works for…

Answer 11

Speed up elimination with dabigatran only

Question 12

If there is need for urgent surgery and still therapeutic effect, what experimental treatment could be discussed with haem?

Answer 12

activated prothrombin complex concentrate , prothrombinex, tranexamic acid
Restrict use to when supportive measures alone will not be enough

Note if normal PT or APTT for the relevent drug, unlikely to help if given pro haemostatic agents.

Question 13

How would you convert to heparin from a noac?

Answer 13

Rivarox/apix:Wait one half life after last dose then dont use loading dose of heparin

Dabig: 12-24 hours where crcl over 30
wait 48 hours if less than 30 (remember LMWH not recommended if Cr Cl under 30)

Question 14

how do you switch from warfarin?

Answer 14

When INR is 2.5 or less, then start NOAC the next day

Question 15

How do you switch TO warfarin?

Answer 15

a few days after starting warfarin, stop NOAC- depends on renal function as this will influence warfarin onset Stop NOAC when INR over 2 for 2 days

Question 16

Should activated charcoal be considered?

Answer 16

If within 2 hours of last dose

Question 17

Rivaroxaban trial for AF?

Answer 17

ROCKET-AF

• Rivarox vs Warfarin in non valvular AF
• Noninferior to warfarin for stroke and bleeding risk
• Less ICH and fatal bleeding
• No difference in rates for major bleeding

Question 18

Apixaban AF trial?

Answer 18

ARISTOTLE

• Apix vs warfarin
• Nonvalvular AF, no DAPT patients
• Improved mortality, bleeding, stroke rates

Question 19

DABIGATRAN AF trial?

Answer 19

RELY
150mg- Dabig less stroke than warfarin, similar bleeding risk
110mg lower major bleeding, similar stroke, embolism
Both reduced ICH, increased GI bleeding and common dyspepsia