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The pharmacology of oral anticoagulants: implications for therapy
H G Shetty1, F Woods, P A Routledge
1Department of Pharmacology and Therapeutics, University of Wales College of Medicine, Cardiff, UK.
Abstract:
All oral anticoagulants act by producing a functional deficiency of vitamin K, thereby impairing the normal synthesis of factors II, VII, IX and X. All, except dicumarol, are well absorbed after oral administration. They are highly protein bound and are mainly metabolized in the liver. A number of factors such as altered absorption, distribution, elimination, genetic factors, aging, vitamin K excess or deficiency, alterations in the level of vitamin K-dependent coagulation factors and drug interactions may affect response to oral anticoagulants. Adverse effects include hemorrhage, skin necrosis and teratogenicity. Phenindione can also cause serious hypersensitivity reactions. Five oral anticoagulants are available in Europe, although warfarin, phenprocoumon and nicoumalone (acenocumarol) are the most commonly used agents. The choice of oral anticoagulant is often influenced by previous experience and familiarity, but in a survey of 22 clinical pharmacologists in 12 countries of Europe, warfarin (57%) or phenprocoumon (24%) were the agents recommended most often in clinical practice.
Insights
Oral anticoagulants reduce vitamin K, impacting clotting factors II, VII, IX, and X. Factors like drug interactions and genetics influence patient response to these essential medications.
Area of Science:
- Pharmacology
- Biochemistry
Background:
- Oral anticoagulants function by inducing vitamin K deficiency, which inhibits the synthesis of coagulation factors II, VII, IX, and X.
- These drugs are generally well-absorbed orally, extensively protein-bound, and primarily metabolized by the liver.
Purpose of the Study:
- To review the mechanisms of action, influencing factors, adverse effects, and clinical usage of oral anticoagulants.
- To identify the most commonly used oral anticoagulants in Europe and their recommended agents in clinical practice.
Main Methods:
- Literature review of oral anticoagulant mechanisms, pharmacokinetics, pharmacodynamics, and clinical applications.
- Analysis of survey data on the preferences of European clinical pharmacologists regarding oral anticoagulant selection.
Main Results:
- Response to oral anticoagulants can be affected by absorption, distribution, elimination, genetics, age, vitamin K status, and drug interactions.
- Common adverse effects include hemorrhage, skin necrosis, and teratogenicity, with phenindione also posing a risk of hypersensitivity.
- Warfarin, phenprocoumon, and nicoumalone are the most frequently used oral anticoagulants in Europe.
- A survey indicated that warfarin (57%) and phenprocoumon (24%) are the most recommended agents by European clinical pharmacologists.
Conclusions:
- The selection of oral anticoagulants is often based on clinician experience and familiarity.
- Warfarin and phenprocoumon remain the preferred agents in European clinical practice for anticoagulation therapy.