Comparison of the pharmacokinetics of several polychlorinated biphenyls in mouse, rat, dog, and monkey by means of a physiological pharmacokinetic model.
Physiologic pharmacokinetic analysis of 4,4'-dichlorobiphenyl, 2,2',3,3',6,6'-hexachlorobiphenyl, and 2,2',4,4',5,5'-hexachlorobiphenyl is presented for the dog and monkey, and the results are compared with previous similar analyses for the rat and mouse. The normalized clearances (ml/min/kg body weight) vary considerably between the dog and the monkey; the rat and the mouse show less species variation. The equilibrium tissue-to-blood distribution ratios for parent and metabolite are generally similar for all four species. The fat compartment has the highest parent distribution ratio for all four species, and the metabolite distribution ratios are much smaller than the parent distribution ratios. Metabolism appears to be a prerequisite to urinary and biliary excretion for all three compounds in each species. Elimination from the body occurs predominantly by the fecal route. The 2,2',4,4',5,5'-hexachlorobiphenyl is more slowly metabolized than the 2,2',3,3',6,6'-isomer in all species, which supports the contention that two adjacent, unsubstituted carbon atoms on the biphenyl ring promote more rapid metabolism.