Transient cardiac arrhythmias after single daily maintenance doses of digoxin.

Ten digitalized patients were monitored for detection of cardiac arrhythmias 0 to 8 hr after daily maintenance dose of digoxin in the fasting state. Transient cardiac arrhythmias attributable to digoxin were seen at 2 to 5 hr in 5 subjects. Initial serum concentrations of digoxin were within standard clinical limits in all subjects, but, higher steady-state levels were present in patients with arrhythmias (1.2 to 1.7 ng/ml) than in the others (0.7 to 1.2 ng/ml). The postadministrative serum peak concentrations were also higher in the patients with arrhythmias.

Human serum and myocardium digoxin.

Linear correlation was demonstrated between serum digoxin and papillary muscle digoxin concentrations in patients undergoing mitral valve surgery. The mean ratio of myocardial tissue to serum digoxin concentrations was 6711. This result supports the use of serum digoxin as a guide for assessing the degree of digitalization under steady-state conditions.

Effect of administration of activated charcoal and fibre on absorption, excretion and steady state blood levels of digoxin and digitoxin. Evidence for intestinal secretion of the glycosides.

The effects of activated charcoal and fibre on absorption and stationary plasma levels of digoxin and digitoxin have been studied. The effect of fibre alone is small but an interactive effect on absorption may occur if fibre and digoxin are ingested simultaneously. Charcoal effectively decreases glycoside absorption even when administered after the glycosides. During maintenance therapy with digoxin or digitoxin, charcoal administration decreased the glycoside plasma levels by 31.2% and 18.3% respectively. It is suggested that even digoxin may have a significant biliary excretion and enterohepatic circulation or that this glycoside has a significant intestinal secretion. The therapeutic implication of this study is that charcoal may be of value, not only in the management of acute glycoside poisoning, but also in some cases of more chronic intoxication.

Maximal bioavailability of digoxin from tablets and oral solution in steady state.

Comparison has been made between the absorption of digoxin from Lanoxin tablets and the absorption of international chemical reference substance digoxin from an oral solution. Plasma levels, areas under 24-hour plasma concentration curves and urinary excretion were similar by both formulations in steady state. 78% of the digoxin administered was absorbed from the tablets and 76% from the solution. Rapid dissolution in the intestinal fluids accounts for the high digoxin bioavailability of the tablets.

Thin-layer electrophoresis of serum lipoproteins.

A method is described for semiquantitative study of serum lipoproteins, with particular reference to the very low density fractions involved in transport of triglycerides. Serum samples were subjected to electrophoresis in thin layers of starch granules; lipids were extracted from starch segments and subjected to thin-layer chromatography; lipid fractions were recovered from the adsorbent and quantified colorimetrically. The procedure is applicable to the study of alimentary and endogenous hyperlipidemias in man, and to radioactive tracer experiments. Over-all recoveries of lipids were variable and averaged 81% for cholesterol and 76% for triglycerides.