Kybernin P 500

0 to 18 Years Old

40-60 IU antithrombin per kg of body weight per day depending on the coagulation status. If required by the clinical condition higher dosages may be necessary in individual cases. The antithrombin activity must then be monitored more frequently and should not exceed 120%.

18 Years Old and Above

In congenital deficiency, dosage should be individualised for each patient taking into account the family history with regard to thromboembolic events, the actual clinical risk factors and the laboratory assessment.

The dosage and duration of the substitution therapy in acquired deficiency depend on the plasma antithrombin level, the presence of signs for increased turnover, the underlying disorder, and severity of the clinical condition. The amount to be administered and the frequency of administration should always be based on the clinical efficacy and laboratory assessment in the individual case.

The number of units of antithrombin administered is expressed in International Units (IU), which are related to the current WHO standard for antithrombin. Antithrombin activity in plasma is expressed either as percentage (relative to normal human plasma) or in International Units (relative to the International Standard for antithrombin in plasma).

One international unit (IU) of antithrombin activity is equivalent to that quantity of antithrombin in one ml normal human plasma. The calculation of the required dosage of antithrombin is based on the empirical finding that 1 International unit (IU) antithrombin per kg body weight raises the plasma antithrombin activity by approximately 1.5%.

The initial dose is determined using the following formula:
Required units = body weight [kg] x (100-actual antithrombin activity [%]) x 2/3.

The initial target antithrombin activity depends on the clinical situation. When the indication for antithrombin substitution is established, the dosage should be sufficient to reach the target antithrombin activity, and to maintain an effective level. The dosage should determined and monitored on the basis of laboratory measurements of the antithrombin activity, which should be performed at least twice a day until the patient is stabilized, thereafter once a day, preferably immediately before the next infusion. Correction of the dosage should take into account both signs of increased antithrombin turnover according to laboratory controls and clinical course. The antithrombin activity should be maintained above 80% for the duration of the treatment, unless clinical particulars would indicate a different effective level.

It should be kept in mind that the half-life of antithrombin may be substantially shortened in certain clinical conditions, such as disseminated intravascular coagulation.

The usual starting dose in congenital deficiency would be 30-50 IU/kg. Thereafter, dosage and frequency, as well as duration of treatment should be adjusted to the biological data and clinical situation.