Determination of volume of distribution for ethanol in male and female subjects

Ten nonalcoholic subjects gave written informed consent. Six men (aged 25-43) and four women (aged 25-35) were hydrostatically weighed to determine their percentage of body fat and lean weight. Each subject fasted for at least 10 h and then received an oral dose of alcohol (0.9 g per kilogram of lead body weight) calculated to yield a peak alcohol concentration of 0.100 g/210-L breath. Breath alcohol measurements were conducted at 20-min intervals until each subject's alcohol concentration returned to 0.000 g/210-L breath. All alcohol analyses were conducted on the Intoxilyzer 5000 and reported as g/210-L breath. Female subjects on average reached a lower peak alcohol concentration (mean, 0.086; range, 0.074-0.091 g/210 L) than male subjects (mean, 0.096; range, 0.093-0.101 g/210 L). Females demonstrated a higher average rate of elimination (mean, 0.017; range, 0.014-0.021 g/210 L) than males (mean, 0.015; range, 0.013-0.017 g/210 L). Female subjects on average had a higher percentage of body fat (mean, 26.0; range, 16.7-36.8%) than males (mean, 18.0; range, 10.2-25.3%). The average volume of distribution (Vd), as calculated from percentage of body fat, for the women (mean, 0.63; range, 0.54-0.71) was less than for the men (mean, 0.69; range, 0.63-0.76). The average Vd as calculated from linear regression of the alcohol concentration curve, for the women (mean 0.64, range, 0.56-0.71) was also less than for the men (mean, 0.72; range, 0.67-0.77). The data from this limited study indicate that hydrostatic weighing is an acceptable way of determining Vd for both men and women.