Synthesis and disposition of 14C-labelled 81/470, a new anthelminthic agent in rats.

CDRI compound 81/470 (AH) is a new broad-spectrum anthelminthic agent under development for clinical and veterinary application. We herewith report the synthesis of 14C-labelled AH, and a study of the tissue distribution and excretion of radioactivity after administering a single 1 mg/kg p.o. or i.v. dose in young male rats. After oral administration of the dose, percent radioactivity recovered in 24-h urine, faeces and tissues were 17.9, 59.7 and 22.9 respectively. The levels were below detection limit in brain and gonads up to 24 h. In bile-duct-cannulated rats, the majority (37.8 +/- 2.8 and 43.8 +/- 6.4) of the radioactivity was excreted in the bile within 24 h of p.o. and i.v. administration, respectively. After an oral dose (1 mg/kg), the urinary excretion of radioactivity in rats was found to be approximately one-half (21 +/- 5.7, 18.3 +/- 2.1) of that obtained by i.v. administration of an equal dose (40.2 +/- 3.1 and 35 +/- 1.3), in bile-duct-intact and cannulated rats respectively.