The absorption of [G-3H]-acetylglycyrrhetate after oral administration to rats.

A tritium-labelled form of aluminium acetylglycyrrhetate has been synthesised by catalytic exchange with tritiated water. An oral dose of aluminium [3H]-acetylglycyrrhetate to rats was mainly excreted in the faeces (a mean of 73%). A mean of 4% was excreted in the urine and after five days 17% of the radioactivity was retained in the carcass. The amounts of non-volatile (drug-related radioactivity excreted in faeces and urine during five days were 65% and 3%, respectively, while 6% was retained in the carcass. The total amount of tritiated water produced was 24% of the dose. Experiments in rats with cannulated bile ducts indicated that much of the faecal radioactivity represented unabsorbed drug. 15% of an oral dose was eliminated in bile during 2 days. A minimum value for the extent of absorption of an oral dose was estimated as 21%. Plasma levels of radioactivity were very low and peak levels of drug-related radioactivity were reached at 30 min and represented about 0.2% of the dose in total plasma.