Pharmacokinetics of digoxin.

The pharmacokinetics of digoxin, the most frequently used digitalis preparation, are reviewed. The dominate serum turnover time is about 34 hours, and is not affected by the route of administration. Excretion is largely as unchanged digoxin in the urine and this excretion is compromised in renal failure. Serum levels of digoxin (determined by radioimmunoassay) are generally available and are useful clinically in assessment of both toxicity and the state of underdigitalization, even though significant overlap exists. Special problems are presented in patients with myocardial infarction, pulmonary heart disease, and thyroid disease.