The pharmacokinetics of propofol (2,6 diisopropylphenol) were compared in 12 patients aged 65-80 yr and 12 patients aged 18-35 yr. After premedication with papaveretum i.m., anaesthesia was induced with propofol 2.0 mg kg-1 in the elderly and 2.5 mg kg-1 in the younger patients. Alcuronium 12-20 mg was then given and the patient's lungs ventilated with halothane and nitrous oxide in oxygen. Blood was taken after various time intervals up to 24 h for the measurement of propofol concentrations by HPLC and for the estimation of propofol protein binding. The mean blood propofol concentration was generally higher in the elderly group, but this difference was only significant at 2 min after induction. The clearance of propofol was significantly lower in the elderly (1.44 +/- 0.10 (SE) litre min-1) than in the younger patients (1.79 +/- 0.12 litre min-1). The volume of the central compartment in the elderly patients was significantly smaller (19.6 +/- 5.2 litre) than that in the young (26.3 +/- 2.9 litre). There was no difference in the volume of distribution at equilibrium (1608 +/- 246 litre in the elderly and 1757 +/- 360 litre in the young), in the volume of distribution at steady state (691 +/- 139 litre in the elderly and 771 +/- 236 litre in the young) or in the half-lives of distribution and elimination. The plasma protein binding of propofol was similar in both groups and showed no trend with time after dose.

In a study where the psychometric assessments were shown to be sensitive to impairment, L-CTZ 5 mg was found following both initial and repeated doses, but also to be demonstrably free from disruptive and sedative effects on objective measures of psychomotor and cognitive function. Similarly, CTZ showed evidence of pronounced antihistaminic activity and significantly reduced weal and flare scores after both acute and repeated doses, again without evidence of cognitive or psychomotor impairment. LOR also was non-sedative but the antihistaminic reaction was demonstrably weak.

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