The pharmacokinetics of alcohol excretion in human perspiration

The elimination of ethanol (ETOH) as a gas in human insensible perspiration (PAC) was investigated following the oral administration of 0.5 g/kg or 0.75 g/kg of alcohol. Simultaneous breath alcohol analysis (AAC) was also carried out for comparison purposes. To determine reproducibility, one subject experienced five trials at each dose over a period of six months, in addition to a single dose (0.5 g/kg) trial with five other subjects. All ETOH concentrations were determined by gas chromatography (GLC). A one-compartment open model with first order absorption and pseudo-zero-order elimination was used to compute the pharmacokinetic parameters. The average first order absorption rate constant (K alpha) and pseudo-zero-order elimination rate constant (beta) for ten trials in a single subject were: K alpha AAC = 1.60 h-1 and 1.39 h-1, beta AAC = 0.154 g/l/h and 0.192 g/l/h. K alpha PAC = 1.27 h-1 and 1.11 h-1, beta PAC = 0.109 g/l/h and 0.141 g/l/h for 0.5 g/kg and 0.75 g/kg ETOH, respectively. In all experiments, AAC was consistently higher than PAC during active absorption, with significantly higher (p less than 0.05) average peak concentration (Cmax) and shorter (p less than 0.05) average time to peak (tmax). However, during the later stages of elimination, AAC falls below PAC, with a significantly faster (p less than 0.05) elimination rate (beta). The data indicates that ETOH elimination via perspiration does not parallel the breath and that the pharmacokinetic parameters are significantly different.