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.