Permeation of Skin and Eschar by Antiseptics II: Influence of Controlled Burns on the Permeation of Phenol

□ The safe antiseptic use of phenol over the burn-traumatized surface depends on knowledge of how the systemic accumulation of phenol is affected by burn processes. To gain insight into the underlying permeation phenomenon, the diffusion of phenol and a reference cosolute, methanol, through both scalded and branded dorsal skin sections of the hairless mouse was studied as a function of burn temperature using in vitro diffusion cells. Temperatures up to 100 and 150° were used for scalding and branding, respectively, using a 60-sec exposure time. Permeability coefficients of the traumatized skins were assessed at 37° and compared with control values. Coefficients of both permeating species were not increased significantly by burn temperatures up to 70° applied either by scalding or branding, however, at higher temperatures exaggerated increases in permeation rates were noted. A limiting increase of ~7 times the control value was noted for phenol irrespective of the burn method. Permeability of methanol was altered even more dramatically and at 100° by scalding and 150° by branding was over 50 times the control rate. At 80 and 100° for methanol and at 80° for phenol, scalding produced larger increases in the permeability coefficients than branding. Since contact for 1min at 60° is capable of producing a full-thickness burn injury, it is clear that eschar permeability to phenol immediately postburn is not related to the clinical degree of burning, but is a function of the thermal intensity (hotness) of the burn stimulus. Full-thickness wounds can be expected to have highly variable rates of systemic absorption as a direct consequence of the wide-ranging permeability possible for such burns, with the risks of topical application varying accordingly.