DOACs and Warfarin Flashcards
what does apixaban inhibit
direct inhibitor of FXa
mechanism of action of Apixaban
potent oral reversible direct and selective active site inhibitor of FXa
inhibits free and clot bound FXa and prothrombinase activity
what effect does Apixaban have on platelet aggregation
has no direct effect - indirectly inhibits aggregation induced by thrombin
prevents thrombin generation and thrombus development
dosing of Apixaban
10mg BD for 7 days
then 5mg BD for duration of treatment
when is dose reduction available for Apixaban
two of the following:
- > 80
- <60kg
- creatinine >133
true or false: dabigatran is a prodrug
true - it is a prodrug with no activity
mechanism of action of Dabigatran
competitive reversible direct thrombin inhibitor
following oral administration, dabigatran etexilate is rapidly absorbed and converted to active dabigatran by esterase catalysed hydrolysis in the liver and plasma
what does thrombin enable the conversion of
fibrinogen to fibrin during the coagulation cascade
therefore thrombin inhibition prevents the development of a thrombus
dosing of dabigatran
150mg BD following 5 days of parenteral therapy
when is dose reduction available on dabigatran
available to 110mg BD for those >80 years or also on verapamil
edoxaban mode of action
direct inhibitor of FXa
inhibits free FXa and prothrombinase activity
prevents thrombin generation and thrombus development
dosing of edoxaban
60mg OD following 5 days of parenteral therapy
when is dose reduction available on Edoxaban
dose reduction available to 30 mg OD when 1 or more of these are true:
- renal function between 15 and 50 ml/min
- <60kg
- use of certain medications such as erythromycin and cetoconazol
mode of action of rivaroxaban
direct inhibitor of FXa
prevents thrombus development in the same way as apixaban and edoxaban
dosing of rivaroxaban
15mg BD for 3 weeks then 20mg OD
when is dose reduction of rivaroxaban available
considered reduction to 15mg OD if clinical risk of bleeding and poor renal function is high
mode of action of warfarin
inhibits synthesis of vitamin K
mode of action of warfarin
inhibits synthesis of vitamin k dependent clotting factors
e.g F11, FV11, FIX, FX, protein C and protein S
dosing of warfarin
individualised to maintain target INR for that patient
diagram of mechanism of action of drugs
what is Option A
daily subcutaneous injections of low molecular weight heparin (LMWH) and to start on oral warfarin therapy at the same time
requirements for Option A
- need to see if patient is willing to inject themselves and show them how and confirm technique
- includes provision of a yellow book
what makes option A. a burden on working people
regular INR tests are required
main side effect of option A
heavy bleeding
what happens if you miss a dose of Option A
- if dose is missed before midnight, it should still be taken
- if does is missed after midnight then the dose should not be caught up - patient should tell the clinician of a missed dose at next INR checkup
what can increase INR value
alcohol intake
what is included in option B
direct oral anticoagulant therapy (DOAC)
how is medication of DOACs started
some require 5 days of parenteral therapy before initiation - tablets started after 5 days of injections, not at the same time
what happens if rivaroxaban is taken
4 week initiation pack is commercially available to facilitate the change from 15mg BD to 20mg OD
what happens if there’s a missed dose of dabigatran
if remembered within 6 hours it should be taken, not If after the 6 hours
what medications can be crushed up for use with feeding tubes and go in blister packs of required
apixaban
edoxiban
rivarocxaban
what happens if warfarin is given via feeding tube
enteral feeds required 2 hours before and after each dose - due to vitamin K content of feeds.
what medications are considered safer than warfarin
apixaban and edoxaban
benefits of DOACs
not known to have many interactions with food drink or alcohol
what is praxbind
is an IV infusion to be given if there is emergency surgery requirement of life threatening uncontrolled bleeding - it is a humanised monoclonal antibody that neutralises its anticoagulant effect but is very expensive
what interact with Warfarin
clarithromycin and ibuprofen
commercially available reversal agent for dabigatran
praxbind
commercially available reversal agent for apixaban and rivaroxaban
ondexxya
which drug does not have an available reversal agent
edoxaban
