We have compared the pharmacokinetics of a bolus dose of propofol 2 mg kg-1 in eight patients undergoing Caesarean section with those in eight postpartum patients undergoing sterilization by mini-laparotomy. The Caesarean section group had a total body clearance of (median) 31.5 (range 24.4 - 53.3) ml min-1 kg-1, apparent volume of distribution at steady state 5.10 (2.46 - 6.61) litre kg-1 and mean residence time 161 (52.3 - 251) min; values for the postpartum group were 33.8 (21.5 - 47.2) ml min-1 kg-1, 5.17 (3.47 - 9.09) litre kg-1 and 163 (92.3 - 238) min, respectively. The 95% confidence interval for the umbilical venous to maternal venous ratio of propofol at delivery was 0.62 - 0.86. Plasma protein binding studies showed there was less unbound propofol in maternal plasma (1.28 - 2.29%) compared with umbilical plasma (2.08 - 3.88%) (P < 0.01 ). Neonatal concentrations of propofol were greater than maternal concentrations at 2 h and were in the range 0.05 -0.11 µg ml-1 at 4 h.
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