Chapter 2: Cardiovascular system Flashcards
(472 cards)
Which DOAC has twice daily dosing? Which has once daily dosing?
READ- R E (OD) AD (BD)
Once daily: Rivaroxiban (20mg OD), Edoxaban (30-60mg OD)
Twice daily: Apixaban (5mg BD), Dabigatran (150mg BD)
Which DOAC requires loading?
Treatment of deep-vein thrombosis
Treatment of pulmonary embolism
Apixaban 10mg BD x 7 days
followed by 5mg BD maintenance (loading dose not required for prophylaxis)
Which DOAC interacts with Verapamil and subsequently requires a dose reduction? What other medication has the same interaction?
Dabigatran
Verapamil increases dabigatran levels, so reduce dose of dabigatran (110mg BD as opposed to 150mg BD)
Same with amiodarone- use max dose of 110mg dabigatran with amiodarone
Which one of the DOACs is a DIRECT THROMBIN inhibitor?
Dabigatran is a direct thrombin inhibitor
An INR within ____ units of the target range is generally satisfactory
0.5 units
A target INR of ____ is used for most things! Eg treatment of DVT/PE, AF patients, electrical cardioversion, myocardial infarction…
2.5
Which DOAC needs to be taken with food and at what strength ?
Rivaroxiban 15mg and 20mg needs to be taken with food to increase absorption
Cautionary and advisory labels
Label 10:
Warning: Read the additional information given with this medicine
Label 21 (15 and 20 mg tablets):
Take with or just after food, or a meal
Which DOAC may be crushed an mixed with apple purée/ put through an NG tube before administration?
Rivaroxaban
Which CCBs need to be avoided in Heart failure?
Verapamil and diltiazem and nifedipine, or nicardipine hydrochloride should be avoided in patients who have HF with reduced ejection fraction as these drugs reduce cardiac contractility. Patients with heart failure and angina may safely be treated with amlodipine.
When should a target INR of 3.5 be used? What is the target for most other conditions?
If the patient has a VTE whilst on treatment with warfarin (with an INR above 2).
Mechanical heart valve
Warfarin’s time to peak effect ranges from 3-5 days, so it is not good if immediate effects are needed. DOACs have a much faster onset to action, what is this? Which is the fastest?
1 - 4 hours
Dabigatran fastest: peak action 0.5-2 hours after oral admin
Edoxaban: 1-2 hours onset of action
Apixaban and rivaroxaban take around 2-4 hours to peak
What is the difference between Phytomenadione and Phenindinone?
Phytomenadione (vit k) is the reversal agent for warfarin overdose
*Think phyto fights warfarin
Phenindinone is another oral anticoagulant (coumarin) like warfarin!
*Think phenin is a friend of warfarin
What baseline tests do patients need before commencing on a DOAC? Which DOAC is least likely to be chosen with renal impairment ?
Renal function before treatment in all patients and at least annually thereafter. Dose reduction required in renal impairment
Dabigatran has most caution with renal function: it is CI if CrCl is under 30 ml/min
Which DOACs should not be used in severe liver disease?
Avoid all DOACs in severe liver impairment
We know that warfarin interacts with a lot of the CYP enzyme inhibitors and inducers, Which DOACs also have a similar problem? Can you think of any interactions?
All
CYP3A4 inhibitors (sickfaces.com) effect these: ketoconazole, itraconazole, Inducers effect these: carbamazepine, rifampicin, phenytoin, St. John’s wort
Which DOAC cannot be put in a compliance aid?
Dabigatran
Which DOAC needs the warning label “swallow whole, do not chew or crush”
Dabigatran
Which is more problematic if a dose is missed, warfarin or the DOACs?
DOACs - shorter half life so if dose is missed there is more time without coagulation If dose of DOAC is missed
What is the reversal agent for LMWHs/UH?
Protamine sulfate
Name me three LMWHs
Dalteparin Enoxaparin Tinzaparin
When in pregnancy should warfarin be avoided?
First trimester
Crosses the placenta especially in the third trimester
Safe in breast feeding
*****When used for the prophylaxis of stroke in AF what are the 3 characteristics which are used to identify if a dose reduction is required.
age 80+
body weight 60kg or less
Serum creatinine of 133 or greater
Which DOAC causes the most GI side effects?
Rivaroxaban: constipation, diarrhoea, abdo pain, nausea, vomiting
Also causes: pain in extremities, Pruritis (itching), Rash
What is heparin induced thrombocytopenia and which heparins is it more common with?
HIT= very low platelet count (platelets help blood to clot)
It is an immune mediated reaction that can develop after 5-10 days
More common with UFH than LMWHs
Management: stop the heparin, use Heparinoids