Identification of turkey biliary metabolites of ractopamine hydrochloride and the metabolism and distribution of synthetic [¹⁴C]ractopamine glucuronides in the turkey

Abstract

1. The bile duct cannulated turkey poult (n = 3) dosed orally with [¹⁴C]ractopamine HCl {(1R*,3R*),(1R*,3S*)-4-hydroxy-α-[[[3-(4-hydroxy[¹⁴C]phenyl)-1-methylpropyl]-amino]methyl]-benzenemethanol hydrochloride; 19.9 mg; 9.28 μCi] excreted 37.46 12.1% (mean ± SD) of the administered radioactivity in bile by 24 h post-dosing. 2. A mono-glucuronide, conjugated at C-10 (the methylpropylamino phenol) of ractopamine, accounted for 76.6% of biliary radioactivity. 3. Urine collected from the colostomized turkey poult (n = 3) orally dosed with synthetic [¹⁴C]ractopamine-glucuronides (10.1 mg; 3.6 μCi) contained 11.96 1.0% (mean ± SD) of the administered radioactivity 24 h after dosing, indicating that some absorption of radioactivity occurred. Faeces contained 60.6% of the administered radioactivity and carcasses (with gastrointestinal tracts) contained 23.3% of the starting radioactivity. 4. Five colostomized poults were fitted with bile duct cannulas and were dosed intraduodenally with 10.2 mg (3.6 μCi) synthetic [¹⁴C]ractopamine-glucuronides. Urine and bile contained 15.5 ± 2.2 and 16.8 ± 2.1% respectively of the administered radiocarbon by 24 h post-dosing. Faeces contained 54.3% of the administered radioactivity. Total absorption of the dosed radioactivity averaged 33.4%. 5. Bile and urine collected from the colostomized, bile-duct cannulated bird contained mainly ractopamine glucuronides. Indirect evidence suggests that the dosed ractopamine glucuronides were not absorbed intact.