Warfarin And Noacs Flashcards
what is measured to assess effectiveness of Warfarin
prothrombin time reported as INR
what is the initial dose of warfarin
5-10mg
what is the usual maintenance dose of warfarin
3-9mg daily depedning on INR
name three conraindications to warfarin
within 48hours post partum
haemorrhagic stroke
significant bleeding
can warfarin be used in pregnancy
no stop 6 weeks before conception
can warfarin be used while breast feeding
yes but increased risk of haemorrhage in baby
patients on long term arfarin get their INR checekd how often
every 12 weeks
what are general factors which may potentiate warfarin
liver disease p450 enzyme inhibitors cranberry juice drugs which displace warfarin from plasma albumin such as nsaids drugs that inhibit platelet fn: NSAIDS
inducers of the p450 system do what to the INR
decrease it
inhibitors of the p450 system do what to the INR
increase it
name p450 system inducers
antiepileptics - phenytoin, carbemazepine barbituates st johns wart chronic alcohol intake griseofulvin smoking
name inhibitors of the p450 system
ciprofloxacin omeprazole allopurinol ketoconazole SSRIs sodium valproate acute alcohol intake
when is unfractionated heparin used for VTE prophylaxis
in renal failure
when are patient deemed at high risk of developing a VTE
medical pts with significant reduction in mobility for three days or more
surgical/ trauma pts - particularly ortho pts
anaesthetic over 90 minutes
what are general risk factors for VTE
active cancer or chemo age 60> thrombophilia bmi>35 dehydration HRT / pill varicose veins pregnant or <6wks post partum
what are the three main meds used for vte prophylaxis
fondoparinux (sc injection)
LMWH - enoxaparin
unfractionated heparin
what are the three ops which require vte prophylaxis no matter what
elective hip
elective knee
fragility fractures of pelvis, hip and proximal femur
what are the three options for vte prophylaxis in elective hip
lmwh 10 days following by 75-150mg for further 28 days
lmwh 28 days with stockings
rivaroxaban
what are the three options for vte prophylaxis in elective knee replacemenet
aspirin 75-150mg 14 days
lmwh 14 days and stockings
rivaroxaban
what is given for vte prophylaxis in fragility fractures of pelvis hip or proximal femur
lmwh
fondoparinux sodium
what are the types of LMWH
dalteparin
enoxaparin
tinzaparin
what is fragmin
lmwh - dalteparin
what are contraindications to heparin
endocarditis major trauma epidural haemophilia peptic ulcer cerebral haemorrhage recent surgery to eye or NS thrombocytopenia
he cautious when prescribing heparin in
elderly
severe hypertension
how do you monitor heparin
platelet count should be measured just before treatment
if given for longer than 4 days platelet count should be regularly monitored
what is a common electrolyte abn caused by heparin
hyperkalaemia
if someone is on heparin and are requiring monitoring due to their increased risk of bleeding what is tested
anti factor Xa activity
what else other than heparins and warfarin and noacs can be used in vte
fondoparinux - synthetic but inhibits factor 5
whatn are the tow contraindications to fondoparinux
active bleeding
bacterial endocarditis
what is a common side effect of fondoparinux not including haemorrhage
anaemia
which anti vte drugs are commonly given orally
NOACS
what type of drug is rivaroxaban
direct inhibitor of factor xa
give 3 cautions related to noacs
- increased risk of recurrent thrombotic events in antiphospholipid syndrome
- should be taken with food as less efficient when on empty stomach
- bleeding risk
what is a common side effect of dabigatran
hepatic fn abnormal
what should be assessed before starting dabigatran
renal fn
what coprescribing edoxaban with what do you need to alter the dose of edoxaban because of interactions
concurrent ciclosporin, dronedarone, erythromycin, or ketoconazole.
when stop edoxaban before surgery
at least 24 hours before
how long should a patient be on vte prophylaxis after sugrery
Pharmacological prophylaxis in general surgery should usually continue for at least 7 days post-surgery, or until sufficient mobility has been re-established. Pharmacological prophylaxis should be extended to 28 days after major cancer surgery in the abdomen, and to 30 days in spinal surgery.
what is first line in vte prophylaxis
LMWH
what is first line for treatment of dvt or pe
apixaban or rivaroxaban
provoked dvt
3 mths so long as provokative factor removed
unporvoked
6mths
what is used for rapid reversal of heparin
protamine sulphate
how long does it take for warfarin to work when initiated
2-3 days
if prescribing warfarin and you want the effect to be immediate what do uou need to do
concomitantly prescirbe unfractionated or LMW heparin
for people on anticoagulation inr target is
2.5
for peiple with recurrent dvt/pe with INR>2 then target INR should be
3.5
when should warfarin be stopped before surgery
5 days before elective surgery
if INR>1.5 before surgery what should you do
vitamin K1 (phytomenadione)
emergent surgery on warfarin
if cen be delayed 6-12 hrs then give iv vit k
if not give dried prothrombin complex and IV vitK
