warfarin Flashcards
(27 cards)
warfarin colours and mechanism of action
white= 0.5
brown= 1mg
3mg=blue
pink=5mg
antagonise vit k prevent coagulation works in 48-72hrs
missed dose warfarin
<od
dose
5mg initially then monitor 1-2 days
maintenance = 3-9mg same time each day
monitoring warfarin
INR every 3 months once stable, for warfarin doses and change in clinical conditions
report calciphylaxis painful skin rash - sign of end stage renal disease
duration of tx warfarin
isolated calf dvt= 6 weeks
provoked dvt( coc, leg cast, preg)= 3 months
unprovoked (fib)= 3 months plus / ling term
warfarin and preg
teratogenic
target inr’s (within 0.5u)
2.5: VTE,MI, af, cardioersion mitral vavlves
3.5: recurrent vte if on anticoag and INR >2
S/E warfarin
bleeding;
inr 5.0-8.0/ no bleed= withheld 1-2 dosesreduce maintenance dose measure inr after 2/3 days
if minor bleed at this inr =omit warfarin iv phytomenadione,repeat if inr high after 24hrs, restart when warfarin <5
inr >8/ no bleed = oral phytomenadione,repest if inr still high after 24hr , restart inr <5
if minor bleed at this INR=stop warfarin, iv phytomenadione repeat after 24 restart when inr <5
if major bleed add fresh frozen plasma or dried prothrombin
bleeding rules
symptoms : nose bleed10mins + , cuts that dont stop bleed , red uirne, blood in vomit , tarry stool subarachnoid haemorrhage seizure h/a
1) easy bruise avoid contact spot
2) use soft toothbrush avoid bleeding gums easy bruise
counselling:
bleeding rules,pil, yellow booklet, food interaction ; alcohol binge , cranberry juice ,green leafy veg
etc interaction; miconazole, nsaid , vit e and K supplement
counselling:
bleeding rules,pil, yellow booklet, food interaction ; alcohol binge , cranberry juice ,green leafy veg
etc interaction; miconazole, nsaid , vit e and K supplement
Warfarin and surgery
elective?
VTE high risk
emergency
elective-stop warfarin 5 days before
vte risk; switch to LMWH
high bleed risk= LMWH 48hrs before
eMERGENCY: where warfarin wasn’t stopped give iv phytomenadione alongside
interaction warfarin
increase bleed (nsaid, anticoag heparin doac antiplately ,ssri, venlafaxine tetracycline)
increase anticoag effect (enzyme inhibitors)
decrease anticoag effect (enzyme inducers)
why nsaid and warfarin interact
increase bleed because nsaid has a greater affinity to albumin so more warfarin = more bleed risk
DOAC moa
directly inhibit factor 10a or IIa (thrombin)
DOAC uses and why preferred over warfarin
VTE,non valvular af
preferred: fixed dose regimen ,no monitoring , less food interaction
missed dose doac, how long lasts and types
> 6hrs = missed
lasts 12-24hrs
doc’s = apixaban, dabigatran (special container 4m expiry), edoxaban, rivaroxaban (MHRA ; after food crush tabs)
counselling doac, s/e and monitor
carry alert cards all times
1) bleeding (monitor signs bleed and anemia and rft’s in renal impairment)
if renal impair reduce dose and monitor
c/I doac
1) prosthetic heart vale
2) antiphospholipid syndrome
2) taking other anticoag and significant bleed risk
Rivaroxaban vte prevention dose (recurrent, high risk), vte tx, stroke prevention non valvular , pred atherothrombotic event
Vte prev: replacement 10mg od hip 35 days knee 14
Recurrent vte 10mg OD 6M+ , high risk vte= 20mg od
Vte tx 15mg bd 21 days - 20mg od
Stroke prevention - 20mg 0d
Atherothrombotic event = 2.5mg Bd (12month if after acs - only disc used after artherothrimboticcevent)
Apixaban Eliquis dose
Vte prophylaxis ; replacement 2.5mg bd hip 32-38 days or knee 10-14days
Recurrent vte = 2.5mg bd
Vte tx 10mg bd 7 days , - 5mg bd
Prevention stroke in af ; 5mg bd (2.5mg bd if 80+, <61kg, creatinine 133+
Edoxaban lixiana
Vte prophy, tx , stroke prevention ; 30mg 0d
61+kg = 60mg od
Dabigatran (pradaxa)
VTE PREV 220MG OD HIP 35 KNEE 14
150MG OD (75+, amiodarone, verapamil)
VTE TX / STROKE PREV AF ; 150MG BD
110-150mg; (75+ mod ri, bleed risk,
110mg bd = 80+ verspamil
Interaction doac
Inc bleed- antiplatelet, anticoagulant, ssri,tca, nsaid
Inc anticoagulant effect- enzyme inhibitor
Reduce effect - enzyme inducers
