PHARMACOKINETICS AND PHARMACODYNAMICS OF KETAMINE ENANTIOMERS IN SURGICAL PATIENTS USING A STEREOSELECTIVE ANALYTICAL METHOD^†

SUMMARY

In a randomized, double-blind study, we have examined the stereoselective disposition and phar-macodynamic characteristics of ketamine in surgical patients after i.v. administration of S(+) -ketamine 7 mg/kg body weight (25 patients) or racemic ketamine 2 mg/kg body weight (25 patients). S(+)-Ketamine was not inverted to R(—)-keta-mine. After racemate administration we observed statistically significant (P < 0.01) smaller clearance and volume of distribution for R(-)-ketamine compared with S(+J -ketamine. In contrast, the pharmacokinetic variables of s(+)-ketamine were not significantly different between treatment groups. Systolic and diastolic arterial pressure and heart rate increased significantly (P < 0.005) in both groups. At 1, 3 and 15min after s(+)-ketamine administration, significantly greater increase in systolic and diastolic pressures were observed compared with the racemate group. There was no correlation between the changes in haemo-dynamic variables and plasma catecholamine concentrations, ch remained unaffected after administration of the medications. (Br. J. Anaesth. 1993; 70: 666–671)