Anticoagulants Flashcards
Warfarin inducers? (less drug)
CRAP gpS
C arbamazepine
R ifampicin
A lcohol - chronic
P henytoin
(griseolfin)
(phenobarbitone)
St John’s Wort & Sulfonylurea
Warfarin inhibitors? (more drug)
SiCkfAcE.com + grapefruit juice
S imvastatin (isoniazid) C iprofloxacin - tendonitis/rupture (ketconazole/antifungals) (fluoxetine) A lcohol acute (cardiac/LF) E rythromycin (sulphonamides & Na+ Valproate) (cimetidine) (omeprazole) (metronidazole)
what is never prescribed w/ warfarin?
DOAC
prophylactic LMWH
therapeutic LMWH (unless “bridging”)
normal INR?
0.8 - 1.2
target INR in AF?
2 - 3
target INR in metallic valve?
2.5-3.5 / 3-4
if raised INR, but NOT bleeding, Tx for INR:
- <6
- 6 - 8
- > 8
- minor bleeding + INR>5?
- reduce dose
- omit dose for 2 days, then reduce
- oral Vit K 1-5mg
- IV Vit K 1-3mg
(restart doses when INR <5)
Tx for bleeding, with any raised INR:
- minor
- major
- life threatening
- oral Vit K
- 5-10mg IV Vit K
- prothrombin complex concentrate (Beriplex)
drugs that increase risk of bleeding even if INR in range?
NSAIDs
steroids
aspirin
clopidogrel
how does warfarin work?
Vit K reductase inhibitor
- less reduced Vit K
- less 1972 factor production
- less of clotting cascade
how does heparin or LMWH work?
activates antithrombin III & inhibits thrombin
- therefore less clotting cascade
how do DOACs work?
inhibit factor Xa
- less prothrombin to thrombin
- less fibrin, less clots
what drugs to STOP if Sx of bleeding/ tarry stools/ haemoptysis/ haemaemesis?
warfarin
DOAC
LMWH
antiplatelet
what kind of thrombophrophylaxis is given on admission to hospital?
prophylactic LMWH (dalteparin 5000 U daily S/C)
compression stockings
when would you not give compression stockings?
in PAD
(absent foot pulses)
may cause acute limb ischaemia
monitoring when starting someone on warfarin?
INR daily, or alternate days, until 2-3 on two consecutive occasions
(a meaningful INR can only be obtained 3–4 days after starting Tx)
Then, twice weekly for 1–2 weeks (this should be continued if HT, RF or bleed risk)
Then, weekly measurements until > two INR measurements are 2-3
Thereafter, longer intervals (for example, < 12 weeks, if agreed locally)
Once stable, changes seldom required.
painkiller to avoid prescribing with warfarin?
NSAID (stomach ulcers will be at risk of bleed)
if INR is >1.5 perioperatively?
give 5mg oral Vit K