Thiopentone and buthalitone: the relationship between depth of anaesthesia, plasma concentration and plasma protein binding.

For 24 hr. after intravenous administration of buthalitone or thiopentone, plasma concentrations in young human subjects have been followed. Buthalitone was distributed to the tissues more rapidly but was metabolized at a slower rate than thiopentone. The relationships between these findings and differences in plasma protein binding and oil/water partition coefficients were studied. It is suggested that some of the differences observed in potency between the substances is a reflection of differences in their modes of distribution. No relationship was found between speed of recovery from anaesthesia and plasma barbiturate concentrations.