ICU Primary PrepCast #012- Haematology Part 1- Anticoagulants in ICU
Nov 6, 2018
Dive into the complexities of anticoagulants in intensive care. Explore the pharmacology and uses of warfarin, including its mechanism and risks. Discover the nuances of newer oral anticoagulants like apixaban and rivaroxaban, from their advantages to dosing challenges. Compare heparin with low molecular weight heparins, focusing on their origins and adverse effects. Get insights into monitoring techniques and reversal strategies, all while enjoying a light-hearted quiz at the end!
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Warfarin Mechanism And Delayed Effect
- Warfarin inhibits vitamin K epoxide reductase and prevents activation of factors II, VII, IX, X and proteins C and S.
- Full anticoagulant effect takes 3–5 days and protein C/S short half-lives can cause early procoagulant effect.
Regular INR Monitoring Is Essential
- Monitor INR regularly because warfarin has a narrow therapeutic index and many interactions.
- Target INR is generally 2–3 (2.5–3.5 for mechanical valves).
Why Warfarin Has Many Interactions
- Warfarin interactions occur via pharmacokinetic (enzyme induction/inhibition, protein binding) and pharmacodynamic mechanisms.
- Examples include rifampicin decreasing INR and metronidazole or amiodarone increasing INR.