Disposition of the pulmonary toxin, bleomycin

Abstract

The disposition of bleomycin in rats was investigated with the use of a 57Co-labeled bleomycin radioimmunoassay. Bleomycin (1 mg/kg,ip) reached a peak serum level of 0.70-1.0 μg/ml in 54 ± 4 min (mean ± SE) and was eliminated with a t 1/2 of 32 ± 1 min. The apparent volume of distribution in rats was 184 ± 11 ml/kg. No change in t 1/2 was observed when rats were pretreated with phenobarbital (1 mg/ml in drinking water for 4 days) or exposed to ozone (3 ppm, 24 hr). Probenecid (0.2 g/kg,ip) given 20 min prior to bleomycin administration increased the t 1/2 2-fold. The order of tissue distribution of 57Co-labeled bleomycin 2 hr after ip administration was: kidney ≥ liver > lungs > spleen > heart > thymus. The affinity of 57Co-labeled bleomycin for homogenates of lungs, liver, or kidney was equal.