Percutaneous uptake rate of 2-butoxyethanol in the guinea pig

The percutaneous absorption rate and elimination kinetics of 2-butoxyethanol (ethylene glycol monobutyl ether) were estimated in the guinea pig. An intravenous bolus dose of 42 or 92 mumol/kg of body weight was administered into the jugular vein of 10 pentobarbital-anesthetized animals. Epicutaneous administration of 2-butoxyethanol followed 2.5 h later in one or two sealed glass rings on the clipped back of the animal. Arterial blood samples were obtained and then analyzed for 2-butoxyethanol by gas chromatography. Following the intravenous dose, the apparent total clearance and mean residence time of 2-butoxyethanol were calculated to be 128 ml X min-1 X kg-1 (SD 30%) and 4.7 min (SD 30%), respectively. During the latter part of the 2-h skin exposure, the concentration of 2-butoxyethanol in the blood appeared to level off at an average concentration of 21 mumol/l (SD 45%). The absorption rate through the skin was estimated to be 0.25 (range 0.05-0.46) mumol X min-1 X cm-2 (SD 49%). The skin uptake rate in the guinea pig was extrapolated to man for a comparison of the percutaneous absorption of liquid solvent with respiratory uptake of solvent vapor. The extrapolation indicated a risk of acute adverse effects when large areas of the skin are exposed to 2-butoxyethanol.