Concentration and regional distribution of propofol in brain and spinal cord during propofol anesthesia in the rat.

We evaluated the pharmacokinetics and regional distribution of propofol in the brain and spinal cord during propofol anesthesia in Sprague-Dawley rats, using high-performance liquid chromatographic determination of propofol concentration in brain, whole blood and plasma. We found that the concentration of propofol in the brain increased and decreased expeditiously during and after a 15-min and 30-min period of i.v. infusion of an anesthetic dose (60 mg/kg per h) of propofol. Furthermore, propofol was evenly distributed in the brain and spinal cord during infusion, with a significant inter-individual variation. Upon the establishment of anesthesia 15 and 30 min following intravenous infusion of propofol, the concentration of propofol in the brain, whole blood and plasma was respectively 15.7 +/- 1.9 and 39.4 +/- 2.7 micrograms/g, 4.5 +/- 1.2 and 13.6 +/- 1.3 micrograms/ml and 1.8 +/- 0.5 and 5.1 +/- 0.9 micrograms/ml (mean +/- SEM, n = 6 or 7). These high brain/blood and brain/plasma ratios during anesthesia suggest that propofol manifests a pharmacokinetic profile that is different from at least thiopental.