Haematology Flashcards
What is the mechanism of action of Dabigatran?
Direct thrombin inhibitor
What is the reversal agent for Dabigatran?
Idarucizumab
What is the mechanism of action of apixaban and rivaroxaban?
Direct factor Xa inhibitor
What is the reversal agent for apixaban and rivaroxaban?
Andexanet alfa (recombinant form of factor Xa)
What is the mechanism of action of fondaparinux?
Activates antithrombin III
What is an example of a direct thrombin inhibitor other than dabigatran?
Bivalirudin usually IV
What does unfractionated heparin inhibit?
Thrombin, factors Xa, IXa, XIa, XIIa
What is the mechanism of action of LMWH?
Activates the action of antithrombin III on factor Xa
What are the benefits of LMWH vs standard heparin?
Less risk of heparin induced thrombocytopenia and osteoporosis
How do you monitor standard heparin?
Activated partial thromboplastin time
How do you monitor LMWH?
Anti-factor Xa
How do you reverse heparin overdose?
Protamine sulphate (only partially reverses LMWH)
What is the mechanism of action of warfarin?
Inhibits epoxide reductase preventing the reduction of vitamin K to its active form
This usually works on clotting factors II, VII, IX, X and protein C
What is target INR for mitral valve?
3.5
What things potentiate warfarin?
Liver disease
P450 enzyme inhibitors e.g. amiodarone, ciprofloxacin
Cranberry juice
Drugs which displace warfarin from plasma albumin e.g. NSAIDs
Drugs that inhibit platelet function e.g. NSAIDs
What are inducers of the P450 system?
Antiepileptics e.g. phenytoin, carbamazepine
Barbiturates e.g. phenobarbitone
Rifampicin
St John’s Wort
Chronic alcohol intake
Griseofulvin
Smoking
What are inhibitors of the P450 system?
Antibiotics e.g. cirpofloxacin, clarithromycin
Isoniazid
Cimetidine, omeprazole
Amiodarone
Allopurinol
Imidazoles e.g. ketoconazole, fluconazole
SSRIs e.g. fluoxetine, sertraline
Ritonavir
Sodium valproate
Acute alcohol intake
Quinupristin
Do inhibitors or inducers of the P450 system increase INR?
Inhibitors
How do you reverse warfarin in major bleeding?
Give IV Vitamin K 5mg
Prothrombin complex concentrate (FFP if not available)
How do you manage INR > 8?
Minor bleeding: Stop warfarin, IV Vitamin K 1-3mg, repeat if necessary, restart warfarin when INR <5
No bleeding: Stop warfarin, give oral Vitamin K 1-5mg using IV preparation, repeat if necessary, restart warfarin when INR <5
How do you manage INR 5-8?
Minor bleeding: Stop warfarin, give IV Vitamin K 1-3mg, restart when INR <5
No bleeding: withhold 1 or 2 doses of warfarin and reduce subsequent maintenance dose
What antiplatelets are first line for ACS?
Aspirin and ticagrelor (12 months)
What antiplatelet is second line in ACS if aspirin CI?
Clopidogrel
What antiplatelets are first line for PCI?
Aspirin and prasugrel or ticagrelor (12 months)
Which antiplatelet is first line for TIA, stroke, PAD?
Clopidogrel lifelong
Which antiplatelets are second line for TIA and stroke if clopidogrel CI?
Aspirin (lifelong) and dipyridamole (lifelong)
Which antiplatelet is second line for PAD if clopidogrel CI?
Aspirin lifelong
Which blood product is used for chronic anaemia?
Packed red cells