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 degrees were used for scalding and branding, respectively, using a 60-sec; exposure time. Permeability coefficients of the traumatized skins were assessed at 37 degrees and compared with control values. Coefficients of both permeating species were not increased significantly by burn temperatures up to 70 degrees applied either by scalding or branding, however, at higher temperatures exaggerated increases in permeation rates were noted. A limiting increase of approximately 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 degrees by scalding and 150 degrees by branding was over 50 times the control rate. At 80 and 100 degrees for methanol and at 80 degrees for phenol, scalding produced larger increases in the permeability coefficients than branding. Since contact for 1 min at 60 degrees 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.