0000000000215340
AUTHOR
Svein ØIe
Factors responsible for interindividual differences in the dose requirement of phenprocoumon
The total and unbound plasma concentrations of phenprocoumon and the prothrombin complex activity were determined in 51 patients on phenprocoumon. A 7-fold difference in the dosing rate (10-70 micrograms/kg/day) was required to maintain the prothrombin complex activity at 11-30% of normal. The variation in dosing requirement was mainly due to interindividual differences in the intrinsic clearance of phenprocoumon and only to a minor degree to differences in sensitivity to it. On average patients with myocardial infarction required only 2/3 of the daily dose of phenprocoumon of post cardiac surgery patients and patients with thrombosis and emboli. That difference appeared to be due to higher…
Dose-dependent metabolism and hepatic distribution of phenprocoumon in rats
The dose-dependency of phenprocoumon disposition was determined in rats by iv administration of 0.1 and 1.0 mg/kg doses to separate groups of animals. The intrinsic clearance (unbound clearance) was 33% lower in the animals given 1.0 mg/kg dose than in the animals given 0.1 mg/kg dose. The apparent unbound volume of distribution was 55% lower and the elimination rate constant 54% higher in the high dose group than in the lower dose group. Binding of phenprocoumon to liver showed saturability with a two- to threefold higher apparent unbound fraction of phenprocoumon in liver in animals given the high dose in comparison to animals given the low dose.
Sex-related Differences in Disposition and Response to Phenprocoumon in Rats
Abstract The pharmacokinetics and the pharmacological response to phenprocoumon have been studied in female and male inbred Lewis-Wistar rats. A significantly lower clearance was found in female than in male rats (7.9 ± 1.4 vs 24.5 ± 2.5 mL h−1 kg−1, respectively; t = 15.09, P < 0.001) as well as a lower apparent volume of distribution (288 ± 46 vs 617 ± 105 mL kg−1; t = 7.58, P < 0.001) and a longer half-life (25.5 ± 3.4 vs 17.5 ± 1.8 h; t = 5.16, P < 0.001). The binding of phenprocoumon was higher in female than in male rats (fu: 0.0096 ± 0.0008 vs 0.0124 ± 0.0007, respectively; t = 6.66, P < 0.001). The total (C) as well as the unbound concentration (Cu) neede…