Effect of mineral oil and/or cholestyramine in the diet on biliary and intestinal elimination of 2,4,5,2',4',5'-hexabromobiphenyl in the rhesus monkey.

Addition of mineral oil to the diet (5%) of two rhesus monkeys that were dosed 29 wk earlier with 2,4,5,2',4',5'-hexabromobiphenyl (HBB) produced a 175% increase in fecal excretion of HBB. A third rhesus monkey was provided with a complete biliary bypass, which permitted the reintroduction of the monkey's own bile or the introduction of the same amount of exogenous bile, which was obtained from control donor monkeys. This experimental design made it possible to measure the portion of fecal excretion that was due to biliary elimination and the portion that was due to intestinal elimination. The effect of mineral oil and/or cholestyramine (CSA) on biliary and intestinal elimination of HBB in the rhesus monkey was then investigated. The results show that (1) fecal excretion of HBB and/or metabolites is due to both biliary and intestinal elimination; (2) during the first 2 wk after completion of dosing, mineral oil does not influence fecal excretion of HBB significantly; (3) 6-7 wk after completion of dosing, mineral oil enhances fecal excretion of HBB by 50%; (4) 8 wk after the last dose of HBB, 4% CSA in the diet increases fecal excretion of HBB and/or metabolites by about 50%; (5) mineral oil specifically stimulates intestinal elimination of HBB; and (6) combined administration of mineral oil and CSA results in an additive effect.