Minimum Alveolar Concentration of Isoflurane in Rats Chronically Treated with the Synthetic Cannabinoid WIN 55,212-2

Background: The isoflurane minimum alveolar concentration (MAC) was measured in rats chronically treated with WIN 55,212-2. Methods: The isoflurane MAC was determined in 24 male rats from the end expiratory samples at time of tail clamping under the following conditions: without treatment (MACISO), in rats treated for 21 days with WIN 55,212-2 (MACISO+WIN55) and other group 8 days after stopping treatment for 21 days with WIN 55,212-2 (MACISO+WIN55+8D). Results: The MACISO was 1.32 ± 0.06. In the MACISO+WIN55 group the MAC increase to 1.69 ± 0.09 (28%). After 8 days stopping treatment, MAC did not decrease significantly 1.67 ± 0.07 (26%). Conclusions: The administration for 21 days of WIN 55,212-2 increases the MAC of isoflurane in rats; this effect does not disappear after 8 days of discontinuing treatment with the synthetic cannabinoid.