DISPOSITION OF PROPOFOL AT CAESAREAN SECTION AND IN THE POSTPARTUM PERIOD

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 (3.47–8.09) 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