Effects of age and sex on ketamine anaesthesia in the rat

Intraperitoneal injections of ketamine 75 mg kg-1 in rats of both sexes (age 1--16 weeks) revealed a significant relationship between increased age and decreased duration of sleeping time for both sexes during the first 3 weeks of age. This decrease in sleeping time seemed to be associated with the increased production of the cyclohexanone oxidation metabolite of ketamine. After 3 weeks of age there was a greater sleeping time in the female rat than the male and this seemed to be associated with a greater ability of the male to produce the cyclohexanone oxidation metabolite.