Pharmacokinetics and serum concentration--effect relationship of intravenous deslanoside

The antibodies of two commercially available digoxin-radioimmunoassay kits showed complete equimolar cross-reactivity with deslanoside and were used to determine serum levels of the latter glycoside. The serum concentrations of deslanoside were measured after a single intravenous dose of 1.2 mg in four patients recuperating after acute myocardial infarction. A phase of log-linear elimination (pseudoequilibrium) was reached after 4--8 h, and the biological half-life was 38-77 h (median 51 h). In a second study, the serum concentration was determined daily in 15 patients given multiple intravenous doses of the drug for atrial fibrillation and/or congestive heart failure. Symptoms or signs of digitalis toxicity occurred in six patients given a loading dose of deslanoside followed by daily maintenance doses of 0.4--0.6 mg. One of the patients tolerated a steady-state serum concentration of 3.9 micrograms/L (4.1 nmol/L) without toxicity symptoms. The findings in the remaining 14 patients suggest that the upper limit of the "therapeutic" concentration range is approximately 2.5 micrograms/L (2.7 nmol/L). A significant positive correlation (p less than 0.001) was found between the serum concentration of the drug and serum creatinine. Reduction of the maintenance dose of deslanoside is recommended in patients with impaired renal function.