Partitioning of propofol between blood cells, plasma and deproteinised plasma in sheep

SUMMARY The partitioning of propofol within the blood, when administered in its usual emulsion carrier, has been determined in vitro in sheep. The blood:plasma ratio was found to be 1.13 and the blood-cell:plasma ratio 1.42. When oxalate was used as the anticoagulant, the plasma protein binding was calculated to be 92.6% - slightly lower than reported for dog, rat, rabbit and man. However, when heparin was the anticoagulant, the binding was significantly less, 83.0%. Differences from some results in the literature may be attributable to other workers using propofol without the lipid emulsion carrier. From the results of this study it is argued that anaemia and plasma levels of protein and lipid may affect propofol requirements.