Medical Information: Oral Anticoagulation

It is vital that the haemostatic and anti-haemostatic mechanisms are fully functional and in balance. Even a slight change in certain coagulation factors or inhibitors can lead to excessive blood coagulation and thus to thromboembolism.

More and more persons require life-long oral anticoagulation with vitamin K antagonists, also called coumarin derivatives, as a result of various medical conditions. Some internal and external experts expect the figure of vitamin K antagonist-treated patients globally to reach 10 millions in 2010. For this staggering number of patients, anticoagulation is an important and necessary life-long commitment.

Indication for Anticoagulation

The purpose of anticoagulation by means of drugs is to ensure that the organs are properly supplied with blood despite its altered flow behaviour. The indication must be given careful thought by balancing the benefit for the patient versus the risk of haemorrhagic complications as a result of taking excessive anticoagulation. more

Adjustment of Coagulation

The efficacy of the treatment hinges quite decisively on the adjustment of coagulation to a steady figure within the therapeutic corridor. This can only be achieved through a regime of regular monitoring of values (1). The CoaguChek family of instruments offers a fast, safe and convenient alternative to laboratory testing by either use at the local clinic or by allowing patients to monitor themselves at home. It allows immediate therapeutic decisions anytime, anywhere.

Why regular Anticoagulation Monitoring is important

Oral anticoagulants have a narrow therapeutic range and the response to a standard dose varies widely both between patients and within patients over time. Changes in patient health, lifestyle or diet and other drugs can alter the effectiveness of the medication.

Potential interferences with coumarins requiring anticoagulation monitoring

• Diet: foods high in vitamin K such as sprouts, cabbage, etc.
  
• Alcohol
  
• Drugs: some painkillers, some antibiotics
  
• Stress
  
• Ilnesses: e.g. diarrohea

These potential interferences, added to the fact that each individual has a different reaction to vitamin K antagonists, require that prothrombin time (PT)/International normalised ratio (INR) is monitored regularly. The time within the therapeutic range is considered as a key indicator of the patient's safety in terms of less potential complications such as haemorrhage or thrombosis. Oral anticoagulant dosages are then adjusted by the healthcare professional according to the results of the PT/INR test.

Pomiar co drugi dzie?

Fig. Example of fluctuating INR values of one patient over time. Frequent PT/INR measurements are necessary since an individual patient pattern is not predictable

PT/INR Self-Testing: More responsibility for the patient

Following the adjustment phase and appropriate instruction in the doctor's office or in a specialized training centre, most patients are able to assume responsibility for their own medication. They continue to be supervised and monitored by their physician, but are empowered to be more in control of their condition, hence being more compliant. There are two possibilities for PT/INR testing today:

• The traditional way: A venous sample is tested in a laboratory. It often requires a second visit to the treating healthcare professional.
  
• The self-testing way: A capillary sample is used. The results are ready within 1 minute with the CoaguChek family of instruments and allow immediate therapeutic decision. Testing is done at the doctor's or by the patient himself.

The CoaguChek family of instruments helps benefit from the Coagulation Self-Testing both you and your patient

Statements based on references

Handin RL. Anticoagulant, fibrinolytic, and antiplatelet therapy. In: Braunwald E, Fauci AS, Kasper DL, Hauser SL, Longo DL, Jameson JL, eds. Harrison's.

Please do not hesitate to contact your local Roche representative if you need further information or references.