Pharmacokinetics in laboratory animals of ICI 35 868, a new i.v. anaesthetic agent.

Blood concentrations of ICI 35 868 have been determined in rat, pig, rabbit and cat after single i.v. injections. In all species the initial distribution volume was greater than blood volume and the overall distribution volume was large. Half-lives of the distribution phase were extremely short (1-6 min) and the terminal half-lives were also short (16-55 min). In all species examined a correlation existed between the systemic blood concentration of ICI 35 868 and duration of sleep, with concentrations in the range 1-4 micrograms ml-1 being effective in producing unconsciousness. No changes in pharmacokinetics or in the effective concentration occurred on repeated administration or after infusion.