Disposition of propofol in patients undergoing surgery: A comparison in men and women

The disposition kinetics of propofoi have been determined in 12 patients (six female) receiving propof of 2.5 mg kg^-1 for induction of anaesthesia, which was maintained with 67% nitrous oxide in oxygen and 1-1.5% halothane. Peripheral blood samples were collected at selected times up to 8 h after the injection of the drug, and whole blood propofoi concentrations determined by HPL C with fluorescence detection. Drug concentration-time data were analysed by the non-linear regression program EL SFIT. This showed the data to be describable by a tri-exponential equation, corresponding to a three-compartment model. There were no differences in the derived kinetic indices for the male and female patients, with the exception of a greater Vd^ss: V^γ ratio in the males. The terminal half-life in the male patients was 262 min (SEM 44), and in the female patients 309min(60). Vd^ss was 329 litre (67) and 313 litre (69) in male and female patients, respectively. The clearance in both groups was 1.8 litre min^-1. Seven out of 12 patients showed significant secondary peaks in blood propofoi concentration associated with recovery from anaesthesia.