Anticoagulant Drugs Flashcards
What are the 2 forms of Heparin?
Unfractioned and Low molecular weight (LMWH)
What does Heparin act on to bring about it’s therapeutic effect?
Anti-thrombin
(It Potentiates Antithrombin which is a naturally occuring anticoagulant)
How is unfractioned monitored?
Activated partial thromboplastin time (APTT)
How is LMWH monitored?
Anti-Xa assay,
However there is not usually any monitoring of LMWH required as it’s more predictable.
What are the potential complications of Heparin?
- Bleeding.
- Heparin induced Thrombocytopenia (HITT).
- Osteoporosis with long term use.
How is the risk of Heparin Induced Thrombocytopenia (HITT) monitored?
Monitoring FBC in patients on Heparin.
What is the Reversal Protocol for Heparin?
Stop the heparin (it has a short half life).
Occasionally in severe bleeding,
- Protamine sulphate. Reverses antithrombin effect.
Complete reversal required for unfractioned. Partial reversal for LMWH.
What are examples of Coumarin Anticoagulants?
Warfarin, Phenindione, Acenocoumarin, Phenprocoumon.
What are the mechanisms of action of coumarins?
Inhibition of Vitamin K
Vitamin K is the final Carboxylation of clotting factors…?
Factors 2 (thrombin) , 7, 9 and 10.
Gives platelets their negative charge.
What are proteins C and S?
Protein C and protein S are two important natural anticoagulants in the body that play a role in regulating blood clot formation.
Where are Protein C and S synthesised and what vitamin do they Require?
in the liver - They Require vitamin K for final carboxylation step essential for function.
How does warfarin act in the liver?
Acts as an anticoagulant by blocking the ability of Vitamin K to carboxylate the Vit.K dependent clotting factors, thereby reducing their coagulant activity.
How would Acute thrombosis be treated in hospital with anticoagulants?
Rapid initiation of Warfarin and Heparin (heparin works while warfarin gets up to therapeutic effect)
What test is used to monitor Warfarin?
Prothrombin Time.
(INR calculated and used)
What are the major potential complications of Warfarin?
Haemorrhage (major adverse effect)
Mild - Skin bruising, Epistaxis, Haematuria.
Severe - GI bleed, Intracerebral, Significant drop in Hb.
What factors influence the reversal of Warfarin requirement?
Depends on severity of bleeding and INR.
What is the speed of action of Vitamin K in Warfarin reversal?
6 hrs.
What is the stepwise process of reversal of Warfarin?
Omit warfarin Dose,
Administer oral Vit K,
Administer clotting factors (factor concentrates),
Monitor response.
What are the 2 types of New Anticoagulants?
Direct Thrombin inhibitors (Dabigatran). - ((Used rarely))
Direct activated factor X inhibitors. (Edoxaban, Rivaroxaban, Apixaban)
