Digoxin およびβ-methyldigoxin のTDM

抄録

The relationships between serum glycoside concentrations, which were obtained from patients during maintenance therapy with digoxin (D3) or β-methyldigoxin (β-MD), and patient factors (age, sex, body weight and renal function) were investigated. Serum concentrations were measured by fluorescence polarization immunoassay with TDx digoxin assay kit (Dainabot). From February 1983 to July 1987, a total of 729 serum samples was received by our laboratory for therapeutic drug monitoring of D3 and β-MD and 182 of these samples were used for this study (D3-treated group, n=50; β-MD-treated group, n=132). For the patients with normal renal function (serum creatinine level≤1.3mg/dl) in each group, no significant differences of mean serum glycoside concentrations were observed between male and female, and none were also observed between patients aged over 60yr and ones aged under 60yr. Each serum glycoside concentration was correlated significantly with dose/kg of body weight [D3, r=0.412 (P<0.01); β-MD, r=0.415 (P<0.001)] and also with creatinine clearance [0.25mg D3, r=0.463 (P<0.01); 0.1mg β-MD, r=0.658 (P<0.001)]. When the serum glycoside concentrations were compared between the D3-treated group and the β-MD-treated group, the dosage ratio (β-MD/D3) to obtain the same serum concentrations was 0.6. However, over 60% of patients were given 0.25mg D3- or 0.1mg β-MD as daily dose and its dosage ratio was 1:0.4 (D3-: β-MD). On comparing the distribution of serum glycoside concentrations between both groups during maintenance therapy, the serum concentrations of the β-MD-treated group were found to be lower than those of the D3-treated group (Kolmogorov-Smirnov test: P<0.005).