1 From the Cardiac Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114.
The pharmacokinetics of acetyl strophanthidin (AS) were studied in dogs and human subjects by the use of a newly developed radioimmunoassay. This method has a sensitivity of 0.1 ng of AS per ml and is applicable to direct measurement of AS in unextracted plasma, urine, or bile. After administration of a single intravenous (i.v.) dose of 1.0 mg of AS to 17-25-kg mongrel dogs, the principal exponential decline of plasma AS concentration began 20-60 min after the injection and had a mean half-life (T
Submitted on November 17, 1972
© 1973 American Heart Association, Inc.
Plasma Concentration and Urinary Excretion Kinetics of Acetyl Strophanthidin
) of 83 ± 19 min (sd). Mean total urinary excretion of AS was 13.3 ± 4.8% of the i.v. dose and occurred with a mean T of 79 ± 10 min. Biliary excretion of AS accounted for only 1.5-2.1% of the i.v. dose. After i.v. administration of 1.0 mg of AS to seven human subjects, the principal exponential decline of plasma AS concentration began 10-30 min after the infusion and had a mean T of 2.3 ± 0.2 hours. Urinary excretion of AS, studied in two patients, accounted for an average of 21.8% of the i.v. dose and occurred with a mean T of 2.4 hours. Thus the plasma level T of AS in human subjects is about tenfold shorter than the 22-hour T previously observed for the relatively short-acting cardiac glycoside ouabain, in agreement with the known brief duration of pharmacologic effects of acetyl strophanthidin.
Key Words: Digitalis • Radioimmunoassay • Pharmacokinetics • Biliary excretion
Accepted on December 26, 1972