MEASUREMENT OF PROPOFOL CONCENTRATION IN SHEEP BLOOD AND PLASMA - EFFECT OF STORAGE AT DIFFERENT TEMPERATURES

In planning a study of the pharmacokinetics of propofol in sheep, cont radictions were noted in the literature with regard to loss of propofo l during storage of blood samples. This prompted a study of such loss from samples of sheep blood and plasma during storage at room temperat ure, +4 degrees C and -20 degrees C, for up to 17 days, over a range o f concentrations from 1 to 20 mu g/mL. Samples were drawn from 22 diff erent sheep. Analysis was by the method of Adam et al. (1981). The bes t estimate of the overall mean loss rate was 0.7% per day with 95% con fidence limits of 0.3% to 1.2% per day. The loss rate increased nonsig nificantly with storage temperature. There were very small nonsignific ant differences of loss rate between plasma and blood, between differe nt concentrations, and between genders. There were significant differe nces of loss rate between sheep-up to about 2% per day in blood or pla sma from any one sheep.