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pre reg afsha > blood thinners > Flashcards

blood thinners Flashcards

1
Q

Vit K antagonists - food interactions

A
  • vitamin K found in health foods, food supplements, enteral feeds, large amounts of some green veg or green tea
  • major changes in diet esp involving salads and veg and alcohol can affect AC control
  • pomegranate juice increases INR
  • heavy alcohol can decrease AC effect
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2
Q

warfarin dose

A
  • initially 5-10mg on day 1, subsequent doses dependent on prothrombin time, reported as INR
  • lower induction dose can be given over 3-4 weeks in pt who don’t require rapid AC
  • lower induction dose in elderly
  • maintenance 3mg - 9mg daily, take at same time each day
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3
Q

Name the 3 vitamin K antagonists

A
  • warfarin
  • acenocoumarol
  • phenindione
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4
Q

how do vitamin k antagonists work

A
  • antagonist effects of vitamin k
  • take at least 48-72 hours for AC effect to fully develop
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5
Q

what to do if immediate effect is required with warfarin

A
  • warfarin takes at least 48-72h for AC effect to develop fully
  • immediate effect needed: give unfractionated or LMWH concomitantly
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6
Q

target INRs - 2.5 and 3.5

A
  • 3.5 for recurrent DVT or PE in pt currently receiving AC and with an INR above 2
  • 2.5 for everything else, including AF, treatment of DVT or PE, MI etc
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7
Q

An INR that is within …. units of the target value is generally satisfactory, larger deviations require….

A

0.5 units
dose adjustments

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8
Q

target INR for mechanical prosthetic heart valves depends on…

A
  • depends on type and location of valve and pt-related RF
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9
Q

what to consider if embolic event occurs while anti coagulated at the target INR for mechanical prosthetic heart valves

A
  • consider increasing INR target or adding anti platelet
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10
Q

do not use vitamin K antagonists 1st line in

A
  • cerebral artery thrombosis or peripheral artery occlusion
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11
Q

what is more appropriate for reduction of risk in TIA

A

aspirin

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12
Q

unfractionated or LMWH is usually preferred for…

A

prophylaxis of VTE in pt undergoing surgery

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13
Q

main adverse effect of all oral ACs

A

haemorrhage

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14
Q

What to do if a pt is on warfarin and has major bleeding

A
  • stop warfarin
  • give phytomenadione by slow IV injection
  • give dried prothrombin complex
  • if dried prothrombin complex unavailable, fresh frozen plasma (but less effective)
  • recombinant factor VIIa not recommended for emergency AC reversal
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15
Q

what to do if a pt is on warfarin and INR >8.0 with minor bleeding

A
  • stop warfarin
  • give phytomenadione by slow IV injection
  • repeat dose if INR still too high after 24h
  • restart warfarin when INR <5
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16
Q

what to do if pt on warfarin and has INR >8.0 and no bleeding

A
  • stop warfarin
  • give phytomenadione by mouth using IV prep orally (unlicensed use)
  • repeat dose if INR still too high after 24h
  • restart warfarin when INR <5
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17
Q

what to do if pt on warfarin has INR 5.0-8.0 and minor bleeding

A
  • stop warfarin
  • give phyomenadione by slow IV Injection
  • restart warfarin when INR <5
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18
Q

what to do if pt on warfarin has INR 5.0-8.0 and n bleeding

A

withhold 1-2 doses and reduce subsequent maintenance dose

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19
Q

what to do if pt on warfarin has unexpected bleeding at therapeutic levels

A

always investigate possibility of underlying cause e.g. unsuspected renal or GIT pathology

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20
Q

when to usually stop warfarin before elective surgery

A

5 days before

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21
Q

what to do if INR on day before surgery is ≥1.5 (and warfarin has been stopped for 5 days)

A

give phytomenadione by mouth using IV prep orally (unlicensed use)

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22
Q

what to do with warfarin if haemostasis (bleeding stopped) is adequate following surgery

A

can resume warfarin at normal maintenance dose on evening or surgery or on next day

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23
Q

which pt may require interim therapy (bridging) with LMWH (using treatment dose)

A
  • pt stopping warfarin before surgery who are considered to be at high risk of TE (eg. TE event within last 3 months, AF with previous stroke or TIA, mitral mechanical heart valve)
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24
Q

when to stop LMWH bridging therapy for warfarin before surgery and when to restart

A
  • stop LMWH at least 24h before surgery
  • if surgery high risk of bleeding, do not restart LMWH until at least 48h after surgery
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25
Q

how to reverse AC effect for pt on warfarin who require emergency surgery

A
  • if emergency surgery can be delayed 6-12 hours, give IV phytomenadione to reverse AC effect
  • if surgery can’t be delayed, give IV phytomenadione + dread prothrombin complex and check INR before surgery
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26
Q

Risk of bleeding with aspirin and warfarin DAT & clopidogrel and warfarin DAT - which one is lower?

A

lower bleeding risk with aspirin & warfarin

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27
Q

name the 4 DOACs

A

apixaban, dabigatran, edoxaban, rivaroxaban

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28
Q

Dabigatran is a reversible inhibitor of…

A

free thrombin, fibrin-bound thrombin and thrombin-induced platelet aggregation

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29
Q

apixaban, edoxaban and rivaroxaban are reversible inhibitors of…

A

activated factor Xa which prevents thrombin generation and thrombus development

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30
Q

omitted or delayed doses of DOACs

A

can lead to reduction in AC effect as effect diminishes 12-24h after lose dose taken

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31
Q

reversible agents are available for which DOACs?

A

dabigatran, apixaban, rivaroxaban

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32
Q

reversal agent for dabigatran

A

idarucizumab provides rapid reversal in life threatening or uncontrolled bleeding, or emergency surgery, or urgent procedures

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33
Q

reversal agent for apixaban, rivaroxabam

A

andexanet alfa for reversal in life threatening or uncontrolled bleeding

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34
Q

apixaban indications

A
  • prophylaxis VTE (+ following knee, hip replacement surgery)
  • prophylaxis recurrent DVT, PE
  • treatment DVT, PE
  • prophylaxis stroke and systemic embolism in non valvular AF and at least one RF (previous stroke or TIA, symptomatic HF, DM, hypertension, 75 and over)
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35
Q

indications: edoxaban

A
  • prophylaxis stroke and systemic embolism in non valvular AF in pt with at least one RF (congestive HF, hypertensive, 75 and over, DM, previous stroke or TIA)
  • treatment DVT, PE
  • prophylaxis recurrent DVT, PE
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36
Q

indications rivaroxaban

A
  • prophylaxis VTE (+ following knee, hip replacement surgery)
  • treatment DVT, PE
  • prophylaxis recurrent DVT, PE
  • prophylaxis storke and systemic embolism in pt with non valvular AF and at least one RF: congestive HF, hypertensive, previous stroke or TIA, 75 or over, DM
  • prophylaxis atherothrombotic events following an ACS with elevated cardiac biomarkers (in combination with aspirin alone, or aspirin + clopidogrel)
  • prophylaxis atherothrombotic events in pt with CAD or symptoms PAD at high risk ischaemic events (in combination with aspirin)
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37
Q

indications dabigatran

A
  • prophylaxis VTE following total knee replacement surgery (+ in pt taking concomitant amiodarone or verapamil)
  • prophylaxis VTE following total hip replacement surgery (+ in pt taking concomitant amiodarone or veramapil)
  • treatment and prophylaxis if DVT, PE (+ in pt with moderate RI, increased risk bleeding, + in pt taking concomitant veramapil)
  • prophylaxis stroke and systemic embolism in non-valvular AF with one or more RF e.g. previous stroke or TIA, symptomatic HF, 75 or over, DM, hypertension, concomitant verapamil, moderate RI, in creased risk of bleeding
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38
Q

increased risk of bleeding with these drugs

A
  • acenocoumarol, warfarin, phenindione
  • alprostadil
  • aspirin, ticagrelor, clopidogrel, prasugrel
  • dipyrimadone, prasugrel
  • NSAIDs: caution or avoid
  • citalopram, duloxetine, escitalopram, fluoxetine, sertraline, paroxetine, vortioxetine, venlafaxine
  • omega-3-acid ethyl esters - caution or avoid
  • -tinibs
  • alteplase, tecteplase
  • apixaban, edoxaban, rivaroxaban
  • bemiparin, dalteparin, enoxaparin, heparin, tinzaparin
  • fondaparinux
  • bismuth - caution
  • nicotinic acid
  • streptokinase, urokinase
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39
Q

the following drugs increase exposure to dabigatran, apixaban, rivaroxaban, edoxaban

A
  • fluconazole, itraconazole, ketoconazole - avoid
  • posaconazole - caution
  • nirmatrelvir - avoid
  • mirabegron
  • ranolazine
  • ritonavir - avoid
  • tacrolimus - avoid
  • ticagrelor - monitor and adjust dose
  • verapamil, amiodarone - monitor and adjust dose
  • clarithromycin - monitor
  • dronedarone, avoid
  • azithromycin, erythromycin
  • Cs - avoid
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40
Q

the following drugs decrease exposure to dabigatran, edoxaban, rivaroxaban, apixaban

A
  • fosphenytoin, phenytoin, carbamazepine - avoid
  • rifampicin - avoid
  • st johns wort
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41
Q

effect of alcohol on warfarin

A

heavy drinks: decreased AC effect

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42
Q

abx interactions: warfarin

A

basically they increase AC effect!!
- amox, ampicillin, benzathine benzylpenicillin, benzylpenicillin, fluclox, phenoxy, piperacillin, pivmecillinam : alters AC effect, monitor INR and adjust dose
- azithromycin, clarith, erythromycin: monitor, may increase bleeding
- ceftriaxone - increased bleeding
- chloramphenicol - increased AC effect
- ciproflox: increased AC effect, monitor INR
- demeclocycline, doxy, lymecycline, minocycline, oxytetrea, tetracycline: increased AC effect, monitor INR
- levofloxacin, moxifloxacin, ofloxacin: increases AC effect, monitor INR
- metro: increases AC effect, monitor INR and adjust dose
- trimethoprim: increase AC effect

43
Q

anti-arrhythmic interactions warfarin

A
  • amiodarone increases AC effect, monitor INR
  • dronedarone might increase AC effect, monitor
  • propafenone increases AC effect, monitor and adjust dose
44
Q

warfarin and aprepitant

A

aprepitant decreases AC effect, monitor INR during treatment and for 14 days after

45
Q

autoimmune drugs interactions warfarin

A
  • azathioprine: decreases ac effect, monitor inr
  • leflunomide increases ac effect, monitor inr
  • mercaptopruine decreases ac effect, monitor inr
46
Q

glucocorticoid interactions with warfarin

A

e.g. beclo, beta, hydrocortisone, dexamethasone
- these increase effects of warfarin, monitor inr

47
Q

antiepileptic drugs and warfarin

A

e.g. carbamazepine, phenytoin, fosphenytoin
- decrease effects warfarin, monitor and adjust dose

48
Q

fibrates and statins interaction with warfarin

A
  • bezafibrate, ciprofibrate, fenofibrate, fluvastatin, rosuvastatin - increase AC effect, monitor INR and adjust dose
49
Q

cimetidine and warfarin

A

increases AC effect

50
Q

cranberry, pomegranate, grapefruit - which one to avoid with warfarin

A

all potentially increase effect, esp pomegranate so avoid

51
Q

disulfuram and warfarin

A

increases AC effect, monitor and adjust dose

52
Q

enteral feeds and warfarin

A

vit K containing potentially decrease AC effect

53
Q

anti-fungals and warfarin interactions

A
  • fluconazole, ketoconazole, increases AC effect, monitor INR and adjust dose
  • miconazole greatly increases AC effect of warfarin, avoid unless INR can be monitored closely and monitor for signs of bleeding
54
Q

A pt on warfarin comes in wanting to buy a vitamin she had heard is good for joint pain. What do you do

A

avoid glucosamine, increases AC effect of warfarin!!

55
Q

A patient on warfarin comes in to buy miconazole oral gel for some oral thrush. is this appropriate

A

no, avoid. greatly increases AC effect!!

56
Q

paracetamol and warfarin - is this safe

A

increases AC effect of warfarin, monitor INR

57
Q

tamoxifen and warfarin interaction

A

increases AC effect of warfarin, monitor INR

58
Q

tramadol and warfarin

A

has been reported to increase AC effect of warfarin, caution

59
Q

A patient on warfarin is to be started on a statin. Which ones do you recommend, which ones do you avoid and why

A
  • Avoid fluvastatin and rosuvastatin - increased AC effect, requires monitoring
  • Can use atorvastatin, simvastatin, pravastatin
60
Q

how long after surgery would you start apixaban for prophylaxis of VTE following knee/hip replacement surgery

A

12-24h after surgery

61
Q

Dose for apixaban: prophylaxis of VTE following knee replacement surgery & hip replacement surgery

A
  • hip : 2.5mg BD 32-38 days, to be started 12-24h after surgery
  • knee: 2.5mg BD for 10-14 days, to be started 12-24h after surgery
62
Q

apixaban: treatment of DVT and PE dose, and maintenance

A

10mg BD for 7 days, maintenance 5mg BD

63
Q

apixaban dose: prophylaxis of recurrent DVT or PE

A

2.5mg BD following completion of 6 months AC treatment

64
Q

apixaban dose: prophylaxis of stroke and systemic embolism in non-valvular AF with at least 1 RF

A
  • 5mg BD
  • 2.5 BD in pt with at least 2 of the following: 80 or over, 60kg or less, serum creatinine 133mmol/L and over
65
Q

MHRA DOACs - increased risk recurrent thrombotic events in pt with antiphospholipid syndrome

A
  • increased risk of recurrent thrombotic events associated with rivaroxaban compared to warfarin in pt with antiphosholipid syndrome and Hx thrombosis
  • may be similar risk associated with other DOACs
  • thus DOACs contraindicated in pt with antiphospholipid syndrome
  • consider warfarin instead
66
Q

reversal effects of andexanet alfa should be monitored using…

A

clinical parameters as anti-FXa assay results may not be reliable

67
Q

what to do if pt are switched from warfarin to apixaban

A

stop warfarin before apixaban to reduce risk of over-AC and bleeding

68
Q

DOACs and RI

A
  • exposure to DOACs e.g. apixaban is increased in pt with RI so dose adjustments needed
  • review pt regularly during treatment to ensure dose appropriate
69
Q

Avoid apixaban if CrCl is

A

less than 15ml/min

70
Q

Apixaban dose adjustment when used for prophylaxis of stroke and systemic embolism in non AF in pt with RI

A

2.5mg BD is serum creatinine 133mmol/l and over, 80 years and over, 60kg or less or if CrCl 15-29

71
Q

apixaban monitoring of pt parameters

A
  • signs of bleeding or anaemia
  • stop treatment if severe bleeding
72
Q

apixaban pregnant and BF

A

avoid

73
Q

Edoxaban doses

A
  • body weight <61kg: 30mg OD
  • body weight 61kg and above: 60mg OD
74
Q

Edoxaban max dose if concurrent Cs, dronedarone, erythromycin, ketoconazole

A

30mg

75
Q

exposure of DOACs is increased in pt with

A

RI - dose adjustment

76
Q

discontinue edoxaban …. hours before surgical procedure

A

at least 24h

77
Q

edoxaban pregnancy and BF

A
  • avoid
78
Q

edoxaban RI dose adjustments

A
  • avoid if CrCl <15
  • if CrCl 15-30: 30mg OD
79
Q

monitoring requirements edoxaban

A
  • renal function before treatment and when clinically indicated during treatment
  • hepatic function before treatment and repeat periodically if treatment duration >1 year
  • signs of mucosal bleeding and anaemia in pt at increased risk
80
Q

rivaroxaban dose: prophylaxis of VTE following knee and hip replacement surgery

A

knee: 10mg OD for 2 weeks, to be started 6-10h after surgery
hip: 10mg OD for 5 weeks, to be started 6-10h after surgery

81
Q

rivaroxaban: dose for treatment of DVT/PE

A
  • initially 15mg BD 21 days with food
  • maintenance 20mg OD with food
82
Q

rivaroxaban: dose for prophylaxis of recurrent DVT/PE

A

-10mg OD to be given following completion of at least 6 months of AC treatment
- consider 20mg OD with food in pt at high risk of recurrence

83
Q

rivaroxaban: dose for prophylaxis of stroke and systemic embolism in pt with non valvular AF with at least one RF

A

20mg OD with food

84
Q

rivaroxaban dose for prophylaxis of atherothrombotic events following ACS with elevated cardiac biomarkers in combo with aspirin alone or aspirin plus clopidogrel

A

2.5 BD usually 12 months

85
Q

rivaroxaban dose for prophylaxis atherothrombotic events in pt with CAD or symptoms PAD at high risk of ischaemic events in combination with aspirin

A

2.5 mg BD

86
Q

MHRA: rivaroxaban after trans catheter aortic valve replacement

A
  • increase in all cause mortality, thromboembolic and bleeding events in clinical trial
  • do not use rivaroxaban for thromboprophylaxis in pt with prosthetic heart valves
87
Q

which tablets of rivaroxaban need to be taken with food

advice for people who have difficulty swallowing

A

15mg and 20mg
(can be crushed and mixed with water or apple puree immediately before, and followed by food immediately after, ingestion in pt who have difficulty swallowing

88
Q

can two ACs be prescribed to one patient

A

never (except when switching therapy, or when unfractionated heparin is given at doses necessary to maintain an open central venous or arterial catheter or for catheter ablation)

89
Q

RI and rivaroxaban - cautions and when to avoid

A

caution if CrCl 15-29
avoid if CrCl <15

90
Q

Rivaroxaban renal impairment: dose reduction when used for prophylaxis stroke and systemic embolism in pt with non valvular AF

A
  • reduce dose to 15mg OD if CrCl 15-49
91
Q

warfarin tablet colours

A

0.5mg: white
1mg: brown
3mg: blue
5mg: pink

92
Q

warfarin cautionary and advisory label

A

warning: read the additional info given with this medicine

93
Q

rivaroxaban cautionary and advisory labels:

A

for 15mg and 20mg tabs: take with or just after food, or a meal
for all: warning: read the additional info given with this medicine

94
Q

contraindications for all vitamin K antagonists

A

avoid use within 48h pp
haemorrhagic stroke
significant bleeding

95
Q

All vitamin K antagonists should be used with caution in bacterial endocarditis. if it is otherwise indicated, which one should be given

A

only warfarin

96
Q

non-obvious cautions for all vit K antagonists

A

hyperthyroidism, hypothyroidism, uncontrolled hypertension, peptic ulcer

97
Q

conception and contraception for all vit K antagonists

A

women of CB age should be warned of teratogenicity

98
Q

use of vitamin K antagonists in pregnancy

A
  • if possible avoid in pregnancy, esp in 1st and 3rd trimesters - difficult decisions may have to be made
  • avoid in BF, risk of haemorrhage; increased by vitamin K deficiency
99
Q

which vit K antagonist can colour urine

A

pheninidione - pink or orange

100
Q

vit K antagonists - monitoring

A
  • base line prothrombin determined, but do not delay initial dose whilst awaiting result
  • INR determined daily or alternate days in early days of treatment, then at longer intervals (depending on response), then up to every 12 weeks
  • more frequent testing if change in clinical condition, esp if associated with liver disease, intercurrent illness or drug administration
101
Q

pheninidone labels

A
  • this may colour your urine. this is harmless (orange pink)
  • read the additional info given
102
Q

cautionary labels for dabigatran

A

swallow whole, do not chew or crush
read addition info given with this medicine

103
Q

once a bottle of dabigatran is opened, use within

A

4 months

pre reg afsha (51 decks)

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