Metabolism and disposition of kyushin, a drug containing senso (ch'an su).

The method of enzyme immunoassay (EIA) was developed for measurement of anti-resibufogenin IgG reactive substance (RRS) in plasma and urine of healthy volunteers receiving a Senso containing drug, Kyushin (KY). Unchanged bufalin (BF), cinobufagin (CB), and resibufogenin (RB) and their metabolites in plasma and urine were also measured by EIA after the separation of these compounds by high performance liquid chromatography. In a single dosing study, the concentration of BF, CB and RB in plasma reached maximum at 1-2 hr after drug administration, and the half-lives (T1/2 of these were 15.8, 8.94 and 11.5 hr, respectively. In a multiple dosing study, the concentration of BF, CB and RB measured fitted on the estimated curve calculated from data of the single dosing study. These results suggest that BF, CB and RB, important components of Senso, do not have a cumulative nature.