Pharmacokinetics of biliary excretion of N-nitrosodiphenylamine (NDPA) in animals of different species.

Pharmacokinetic investigations into the biliary excretion of N-nitrosodiphenylamine given as an i.p. dose of 50 mg/kg were conducted and results compared in three animal species; rat, guinea pig and rabbit following bile duct cannulation and collection of bile in vitro. The guinea pig excreted NDPA into bile fastest while the rabbit, which excreted it slowest, eliminated it fastest. Both appearance and disappearance of the nitrosamine were comparatively slow in the rat. NDPA elimination half-life values in the animal species were 510, 240 and 95 min respectively, while cumulative excretions amounted to 12, 3 and 0.3 percent. The toxicological implications of these species differences are highlighted.