Predicted effect compartment concentration of thiopental at loss of eyelash reflex

We derived the predicted effect compartment concentration of thiopental, at loss of the eyelash reflex, following three different injection regimens. Sixty patients were given thiopental for induction of anaesthesia. Twenty p atients received multiple small boluses, 20 patients received a single bolu s and 20 patients received an infusion. Computer simulation was then used t o derive the effect compartment concentration. The median concentration was not significantly different between the three groups. EC50, derived after combining all three groups was 11.3 mug ml(-1). The EC05-EC95 range was 6.9 -18.3 mug ml(-1), suggesting wide inter-individual variation.