Effect of tilorone hydrochloride on hepatic disposition of sulphobromophthalein (BSP) in the rat.

1. Biliary excretion of sulphobromophthalein (BSP) was studied in male rats after oral administration of tilorone HCl, an anti-viral and anti-tumour agent. 2. The stimulation of bile flow by BSP was decreased 1 h after tilorone administration; this decrease was no longer apparent 24 h later but a fall of basal bile flow was noted at that time. No changes in bile flow were observed 7 days after this single dose. 3. Repeated dosing with tilorone produced a dose-dependent increase in hepatic concentration of unchanged and metabolized tilorone. This was associated with a dose-dependent decrease of bile formation and BSP excretion. Bile acid excretion was depressed as well. 4. BSP metabolism was not significantly affected by tilorone administration.