Abstract
The pharmacokinetics of Loprinone hydrochloride, a new cardiotonic agent, was investigated after a single intravenous administration of 14C-labelled compound to dogs.
1. After a single intravenous administration of 14C-Loprinone hydrochloride to dogs, the plasma level of radioactivity rapidly decreased in biexponential manner, with the respective half-lives of 23 min and 5.1 hr.
2. Radioactivity was rapidly distributed to tissues after a dosing. A high level of radioactivity was detected in the kidney and the bile. Radioactivity from all tissues, except choroidea and retina, was rapidly eliminated. And 96 hr after dosing, the levels of radioactivity in all tissues were very low, near the detection limit.
3. Two metabolites of Loprinone hydrochloride were indentified as amine form and enol-O-glucuronide of mother compound in the urine after dosing.
4. Loprinone hydrochloride was hardly metabolized. In the liver, kidney, heart, lung, over 90% of radioactivity corresponded to the unchanged form at 5 min and 1 hr after dosing. And in the urine and feces, the unchanged form was mainly found, however a small amount of metabolites, amine form and enol-O-glucuronide of unchanged form were also detected.
5. Radioactivity, excreted within 24 hr, accounted for 44.7 and 50.1% of dose in urine and feces, respectively, and the total excretion of radioactivity was 99.7% within 96 hr.
