[Anticoagulation with phenprocoumon in early childhood: dosage, complications, effectiveness]

The dose-response relationship of the Vitamine-K-antagonist Phenprocoumon (Marcumar) was studied in a group of 11 children and 10 adults receiving anticoagulation postoperatively after mechanical valve replacement. The dose in children was found to be lineally correlated to the body surface area and similar to that in adults (saturation dose: 16.0 +/- 3.2 mg/m2; maintenance dose: 11.2 +/- 1.6 mg/m2/week). During the follow up period (265 patient months) one child died from mitral valve thrombosis, two children developed traumatic haematomas, and in one child interactions with 2 other drugs were observed. The incidence of thrombembolism or serious bleeding complications was 4.5 and 9.0 instances per 100 patient-years, respectively. The efficiency of prothrombin time control was established over a six months period and showed 70.3% of the values within, 23.% above, and 6.5% below the therapeutic range. During this period, the prothrombin time was measured 2.5 times per patient and month at the average. We conclude from our experience, that an anticoagulation therapy with Phenprocoumon can be performed in children with only mildly elevated risk of bleeding complications as effectively as in adults provided it is monitored closely.