Digoxin kinetics in the elderly.

Digoxin elimination phase kinetics have been studied in 24 hospital in-patients (mean age 79 years), six of whom showed no evidence of digoxin toxicity. The others, with suspected toxicity, have been grouped according to the nature of the drug effects observed. Renal function, digoxin elimination half-life, apparent volume of digoxin distribution, and notional body content of digoxin have been compared between the groups. Apart from two hyperthyroid patients, the volumes of distribution averaged 6.1 1/kg. Toxic patients tended to have lower creatinine clearances, longer digoxin half-lives, and higher body contents of digoxin than the nontoxic, but the highest body contents were found in those with systemic toxicity. Thyrotoxicosis increases the apparent volume of digoxin distribution in the elderly.