This study deals with the measurement of acetylcholinesterase activities in the plasma and brain of 8 rabbits using modified Michael and Ellman methods. The highest values of acetylcholinesterase activities in plasma and brain were 0.37 and 0.25, respectively, when the modified Michel method was employed. In the case of using Ellman method, the highest values of cholinesterase activities in plasma and brain were 0.89 and 0.43, respectively. In order to determine the efficiency and legitimacy of the measured result, the coefficient of variation was calculated. For the modified Michael method, the coefficients of variation in plasma and brain were 17.78 % and 19.37%, respectively. However, in the case of using Ellman method, the coefficients of variation in plasma and brain were 21.72% and 41.21%, respectively. These results were consistent with those reported in the previous studies.

The objective of this study was to examine the effect of ketoprofen with or without combination with xylazine on the level of cyclooxygenase-2 in mice. The intraperitoneal (i.p.) dose of ketoprofen and xylazine that caused an analgesic response in half of the mouse population was 1.26 mg/kg and 6.63 mg/kg, respectively. Serum cyclooxygenase-2 concentration (activity) in the control mice was 16.94 ng/ml. The ketoprofen-treated group (2.52 mg/kg, i.p.) decreased the cyclooxygenase-2 concentration by 58% (7.16 ng/ml). The combined ketoprofen and xylazine treatment (13.26 mg/kg, i.p.) decreased the cyclooxygenase-2 by 94% (0.98 ng/ml). The ketoprofen plasma concentration in the combined treatment group was significantly higher compared to the ketoprofen treatment group. Ketoprofen plasma concentrations measured at 0.25, 0.5, 1, 2, 4, and 24 hours were 19.07, 18.94, 14.66, 6.53, 5.44, and 5.54 µg/ml, respectively. Plasma concentrations of ketoprofen and xylazine were raised to 28.74, 29.74, 15.32, 13.04, 14.64, and 11.95 µg/ml or by 51%, 56%, 5%, 100%, 169%, and 116%, respectively. Ketoprofen pharmacokinetic variables were increased (AUC0-∞ (515%), AUMC0-∞ (2389%), MRT (305%), t1/2β (375%), Tmax (100%), and Cmax (55%)), while other values were decreased (Kel (79%), Vss (25%), and Cl (88%)). Our findings suggested a synergistic interaction between ketoprofen and xylazine on the level of cyclooxygenase-2 (pharmacodynamic interaction) which was exerted by modification of the ketoprofen pharmacokinetic properties in mice.