Sex differences in total body water in adolescent rhesus macaques estimated by ethanol dilution

Non-human primates are widely used in research, yet relatively few studies have addressed potential pharmacokinetic differences between males and females. The present study examined the relationship between total body water, sex, age, and weight in the rhesus macaque (Macaca mulatta). Ethanol-naïve, adolescent rhesus macaques (n = 119) were administered ethanol (males, 2.1 g/kg; females, 2.0 g/kg) intravenously, and blood samples for blood ethanol concentration obtained at 5, 10, and 60 minutes following the end of the infusion. Non-linear regression was used to compare and contrast a series of pharmacokinetic models examining the relationship between weight, sex, age, V(d) and zero-order elimination rate. V(d) (mean +/- SEM) for male rhesus was 0.771 +/- 0.008 l/kg and for females was 0.730 +/- 0.008 l/kg, different at P < 0.00001. There were no sex differences in the rate of zero-order ethanol elimination, estimated to be 0.0032 +/- 0.0004 g/kg/minute. The data reported here may be useful in designing and interpreting pharmacokinetic studies using rhesus monkeys.