[Pharmacokinetics of AR-L 115 BS in rabbits and dogs]

The pharmacokinetics of 2-[(2-methoxy-4-methylsulfinyl) phenyl]-1H-imidazo[4,5-b]pyridine (AR-L 115 BS) were investigated in the rabbit and the dog. The rabbits were dosed with 1 mg/kg 14C-AR-L 115 BS i.v. or p.o and the dogs with 1 mg/kg i.v. or 5 mg/kg p.o. following i.v. administration the blood levels in the two investigated species are described by a 3-exponential decline, during which the preponderant amount of radioactivity is eliminated in the first two phases. The half-lives are 0.25 h and 6 h in the rabbit and 0.2 h and 0.6 in the dog. Following oral administration the radioactivity is absorbed rapidly and quantitatively. Blood level peaks occur after 1 h p.a. amounting to 0.07--0.1 microgram Eq/ml in the rabbit (1 mg/kg) and 2.7 +/- 0.3 micrograms Eq/ml in the dog (5 mg/kg). The elimination behaviour is comparable to that after i.v. dosing. The plasma radioactivity in the dog is not protein bound. On average the urinary excretion amounts to 45% (i.v) and 40% (p.o.) in the rabbit, with a further 52% (both application routes) in the faeces up to 144 h p.a. In the dog the mean urinary excretion is 24% (i.v.) and 29% (p.o.). Faecal elimination is 63% (i.v.) and 56% (p.o.) up to 96 h p.a.