[Pharmacokinetics of epirubicin in cancer patients]

The plasma levels of epirubicin and its metabolite, epirubicinol, were measured by HPLC following intravenous administration of epirubicin to cancer patients at doses of 40, 60, 80, and 100 mg/m2. The blood concentration/time curve declined as a tri-phasic function. The mean t1/2 alpha, beta, and gamma were 4.67 min, 1.15 h, and 36.5 h, respectively, which were characterized by a short distribution phase (alpha) and a prolonged elimination phase (gamma). The distribution volume of the central compartment (V1 = 0.351 l/kg) was small, while that of the tissue compartment (V2 = 0.254, V3 = 45.8 l/kg) was large, which could be explained by the binding of the drug to cellular components. The concentration of epirubicinol, although having a wide variation among individuals, was less than that of the unchanged drug and showed a gradual decline. The area under the curve (AUC) of epirubicin increased in proportion to the increase of dosage. These types of pharmacokinetic behavior of epirubicin appeared to be similar to those of doxorubicin.