[Analysis of phenprocoumon dose regulation based on measurement of coagulation factors II, VII and X]

One hundred anticoagulation treatment records were reviewed retrospectively using stepwise regression analysis to determine the influence of phenprocoumaron on the levels of coagulation factors 2, 7 and 10 (KF) measured relative to normal. The phenprocoumaron dose was expressed relative to the correct maintenance dose determined from the entire record ("overdose", OD measured in mg). Phenprocoumaron treatment influenced the KF over two days, approximately 50% on each day, the total change being -0.03 x OD. Continuous incorrect dosage resulted in KF change, equilibrating at a new level after about four weeks at -0.47 x OD. Similarly, continuous correct dosage in patients with a non-therapeutic FK resulted in equilibration within the therapeutic range after four weeks. For long-term treatment, the dosage was likely to be inaccurate under the following circumstances: 1) if the KF was outside the therapeutic range and moving away from it; 2) if the KF was inside the therapeutic range and the change was greater than 0.05. Algorithms for calculation of phenprocoumaron therapy are presented.