VEHICLE EFFECTS ON IN-VITRO PERCUTANEOUS-ABSORPTION THROUGH RAT AND HUMAN SKIN

We studied the effects of three vehicles (propylene glycol, octanol an d ethyl decanoate) with differing polarity on the in vitro percutaneou s absorption of three chemicals (fluazifop-butyl, dimethyl phthalate a nd fomesafen sodium salt) with a range of physicochemical properties. Absorption rate measurements were made from high vehicle volume (200 m u l/cm(2)) and low vehicle volume (<10 mu l/cm(2)) applications. For t he lipophilic fluazifop-butyl absorption rate was highest from the mor e polar vehicle propylene glycol, but this effect was only significant under high-volume conditions. There was a variable vehicle effect on absorption of the intermediate chemical dimethyl phthalate. The larges t vehicle effect was seen for the more hydrophilic fomesafen sodium sa lt where absorption was fastest from the least polar vehicle ethyl dec anoate. These results support the hypothesis that the absorption proce ss can in part be predicted from a knowledge of solute solubility. Veh icle effects were greater from high volume applications than from thos e more comparable to occupational exposure conditions.