antiplatelets and anticoagulants Flashcards
What classess of antiplatelets are there? examples from each?
COX-1 inhibitor
- aspirin
PY12 inhibitor
- clopidogrel
- ticagrelor
- ticopidine
- prasugrel
Phosphodiesterase inhibitor
- dipyridamole
- cilostazol
common side effect aspirin
dyspepsia, hameorrhage
how to prevent a common adverse effect aspirin
prescribe PPI if risk of gastric complications eg >65, previous peptic ulcer disease, comorbidities, taking other gastric damaging drugs eg NSAIDs and steroids
contraindications to aspirin
children under 16 (risk of reyes syndrome- brain swelling and liver damage), allergy to aspirin or another NSAID, avoid in 3rd trimester as prostaglandin inhibition may prematurely close ductus arteriosus,
medical
ischemic stroke 300 mg for 2 weeks then 75mg
75mg clopidogrel for secondary prevention of isc stroke
dose aspirin ACS
300mg once-only dose then 75 mg daily
what class of drug is clopidogrel
P2Y12 inhibitor
what class of drug is ticagrelor
P2Y12 inhibitor
what class is prasugrel
P2Y12 inhibitor
what is your DOAC of choice for PSA
rivaroxaban
what is your LMWH of choice for PSA
enoxaparin
what classes of antiplatelets are there
Direct
Factor Xa inhibitors
- rivaroxaban
- apixaban
- edoxaban
Thrombin inhibitors
- dabigatran
Indirect:
Vitamin K antagonist (oral)
- warfarin
Heparin
- UFH
- LMWH
Fondaparinux
interpretation of wells score for PE
PE likely - more than 4 points
1. arranage immediate CTPA
+ if delay in CTPA, interim therapeutic anticoagulation = direct oral anticoagulant (DOAC) such as apixaban or rivaroxaban
if the CTPA is positive then a PE is diagnosed
if the CTPA is negative then consider a proximal leg vein ultrasound scan if DVT is suspected
PE unlikely - 4 points or less
1. d-dimer
2. if +ve –> CTPA and interim therapeutic anticoagualtion if delay
ECG changes PE
most common = sinus tachycardia
classical = ‘S1Q3T3’ a large S wave in lead I, a large Q wave in lead III and an inverted T wave in lead III
what other invetsigation shoult pts with ?PE get?
a chest x-ray is recommended for all patients to exclude other pathology
however, it is typically normal in PE
possible findings include a wedge-shaped opacification
First line anticoagulant therapy for PE
RIVAROXABAN or apixaban
Second line treatment for PE if DOAC CI
LMWH followed by dabigatran or edoxaban OR LMWH followed by a vitamin K antagonist (VKA, i.e. warfarin)
Management of PE if severe renal impairment eg egfr <15/min
LMWH, unfractionated heparin or LMWH followed by a VKA
Management of PE in antiphospholipid syndrome
LMWH followed by a VKA should be used
length of anticoagulation for PE
provoked = 3 months
active cancer = 3-6 months
unprovoked = 6 months
Management of PE with haemodynamic instability ie circulatory failure (e.g. hypotension)
thrombolysis
what score should you calculate if DVT is a ddx
Two-level DVT Wells score
DVT likely: 2 points or more
DVT unlikely: 1 point or less
how many points is ‘likely’ for dvt on two level wells score? management
2 or more
1. a proximal leg vein ultrasound scan should be carried out within 4 hours
- if +ve = start anticoagulant
- if -ve = a D-dimer test should be arranged. A negative scan and negative D-dimer makes the diagnosis unlikely and alternative diagnoses should be considered
- If proximal leg vein ultrasound cannot be performed within 4 hours then a D-dimer test should be performed and interim therapeutic anticoagulation administered whilst waiting for the proximal leg vein ultrasound scan (which should be performed within 24 hours)
- rivaroxaban or apixaban
- if the scan is negative but the D-dimer is positive:
stop interim therapeutic anticoagulation
offer a repeat proximal leg vein ultrasound scan 6 to 8 days later
how many points is ‘unlikely’ for dvt on two level wells score? management?
- perform a D-dimer test
- this should be done within 4 hours. If not, interim therapeutic anticoagulation should be given until the result is available
if the result is positive then a proximal leg vein ultrasound scan should be carried out within 4 hours
if a proximal leg vein ultrasound scan cannot be carried out within 4 hours interim therapeutic anticoagulation should be administered whilst waiting for the proximal leg vein ultrasound scan
if the result is negative then DVT is unlikely and alternative diagnoses should be considered
How long should anticoagulation be continued DVT
provoked - 3 months
active cancer - 3-6 months
unprovoked - 6 months
define provoked dvt
due to an obvious precipitating event
e.g. immobilisation following major surgery.
The implication is that this event was transient and the patient is no longer at increased risk
what score should be used to assess bleeding risk anticoagulation
ORBIT score
