Individualization of drug dosage during long-term treatment with phenprocoumon (Falithrom)

Pharmacokinetic studies were carried out with 3H-phenprocoumon (3H-PPC) during long-term treatment with phenprocoumon (PPC, Falithrom) in 10 female and male patients with thromboembolic diseases. Additionally, 12 mg 3H-PPC were administered per os to 6 male volunteers. Half-life and pattern of urine metabolites were measured and compared with those in patients. The radioactivity decreased independently of the total PPC plasma concentration, which was estimated fluorometrically. An exponential regression with a high coefficient of determination was found between the mean maintenance dose (PPC) and the area under plasma concentration curve of radioactivity. This procedure is considered to be a method to improve long-term treatment with PPC.