Absorption, distribution and excretion of [3h]rubescensine a in mice

Rubescensine A was isolated from Rabdosia rubescens Hemsl. [3H]rubescensine A was injected ip 3.03 mg (1 mCi)/kg to mice. The drug was rapidly taken up by various organs. The highest radioactivities were found in gall bladder, intestine, liver and kidney, then the pancreas and esophagus. The lowest radioactivities were found in thymus, bone marrow, heart and brain. The excretion amounted t0 53% of the injected radioactivity within 24 h in feces and urine. Atter iv, the plasma radioactivify showed an initial rapid drop and a subsequent slow decline. The disappearance curve was analysed on the basis of a triexponential curve representing a model consisting of 3 compartments. T1/2 =1.5+0.4 min,T1/2a = 181+ 4 min and T1/2b = 202+13 min. The central volume (Ve) = 0.41+0.91 l/kg.