In a prospective randomized study 12 patients suffering from
cirrhosis of the liver (stable phase) and 12 healthy volunteers were treated daily with either 0.3 mg
metildigoxin (
Lanitop) or 0.4 mg
beta-acetyldigoxin (
Novodigal) orally. Every day the total serum
digoxin concentrations of the patients and volunteers were measured by radioimmunoassay. Both
digoxin and
beta-methyldigoxin are measured by this method. In patients receiving
metildigoxin therapy the ratio of
beta-methyldigoxin/
digoxin in the serum was determined by HPLC. The
digoxin levels in patients with
cirrhosis treated with
metildigoxin were statistically significantly higher than in healthy volunteers. In patients with
cirrhosis the proportion of serum
beta-methyldigoxin averaged 77.7% of the total
digoxin concentration, whereas the proportion was only 37.5% in healthy volunteers. With
beta-acetyldigoxin there was no statistically significant difference between patients with
cirrhosis and healthy volunteers. The higher total serum-
digoxin levels in patients with
cirrhosis of the liver after moderate saturation with
metildigoxin are caused by reduced demethylation of
beta-methyldigoxin to
digoxin due to impaired liver function. A comparison with healthy volunteers showed that the reduced hepatic metabolism in the cirrhotic patients caused changes in the pharmacokinetics: a reduced
metildigoxin clearance and a smaller distribution volume were found. According to our findings there is more danger of digitalis toxicity in patients with
cirrhosis of the liver on a standard dosage of
metildigoxin than on a standard dosage of
beta-acetyldigoxin.