Williams, P.L., J.D. Brooks, N.A. Monteiro-Riviere and J. E. Riviere. Quantitative Percutaneous Absorption and Distribution of Binary Mixtures of Two Phenols in the Isolated Perfused Porcine Skin Flap. The Toxicologist 1995. 15:324.

Phenol - 00108-95-2; p-nitrophenol - 00100-02-7

A total of 62 8-hr isolated perfused porcine skin flap (IPPSF) topical experiments studying binary mixture (solute/solvent) absorption and distribution were conducted on ¹⁴C-labeled phenol vs. p-nitrophenol (PNP); concentration: 4 ug/cm²; vehicle: acetone vs. ethanol; occluded vs. nonoccluded. All IPPSFs were analyzed for absorption, depth of penetration, compound location, and total recoveries. Total recoveries were much greater in all cases for PNP than phenol. Absorption, penetration depth, and total recoveries of phenol were greater under occluded conditions than nonoccluded. Absorption, penetration depth, and total recoveries of PNP were greater under occluded conditions than nonoccluded in the low concentrations, but the opposite was observed with the higher concentrations of PNP. Absorption and penetration depth of phenol were greater with ethanol than with acetone under nonoccluded conditons, but the opposite was observed under occluded conditions. Absorption and penetration depth of PNP was greater with acetone than with ethanol under either occlusion condition. Percent absorption was greater in PNP in acetone than in phenol in acetone occluded or nonoccluded. There was a lower percentage from the higher dose of phenol absorbed, penetrated, and recovered under occluded and nonoccluded conditions and in PNP under occluded conditions, but the opposite was observed (lower percent dose in lower concentration) under nonoccluded PNP conditions. These results suggest that comparative absorption of phenol and PNP are vehicle-, occlusion-, and penetrant-dependent. Occlusion enhanced the vehicle effect on absorption, but reversed the distribution pattern. These findings suggest that single chemical data is not predictive of even binary mixtures and that exposure conditions further modulate disposition.