Pharmacokinetic-metabolic studies with 14C-aloe emodin after oral administration to male and female rats.

After oral administration of 4.5 mg/kg 14C-aloe emodin (AE) to rats 20-30% of the dose was excreted in urine and the rest in feces. AE was quickly metabolized to rhein, to an unknown metabolite and to conjugates of all three. In the plasma about 10% of 14C-activity was identified as free AE. Maximum plasma values were reached 1.5-3 h p.a. with 248 (male) and 441 (female) ng equivalents AE/ml. Maximum concentrations in plasma were about 3 times higher than those in ovaries and 10 times higher than those in testes. Only liver, kidney and intestinal tract showed higher concentrations than plasma. Terminal half-life (for radioactivity) in blood was about 50 h.