Potency of propofol for loss of consciousness after a single dose

A dose-response curve for loss of consciousness after administration of propofol was obtained using 56 unselected, premedicated patients presenting for surgery. Propofol was given in doses according to the calculated lean tissue mass (LTM) of the patient. The end-point for loss of consciousness was loss of ability to grasp a light object. Using probit analysis, the ED50 for propofol was found to be 1.34 mg/kg of LTM and the ED95 was found to be 2.56 mg/kg of LTM. Comparison with previously published data for thiopentone showed propofol to be approximately twice as potent as thiopentone at ED50 and the slope of its dose-response curve to be shallower than that of thiopentone.