Percutaneous absorption of anthracene in the rat: comparison of in vivo and in vitro results.

The present study was conducted to evaluate the applicability of in vitro percutaneous absorption techniques to estimate in vivo absorption of polynuclear aromatic (PNA) compounds commonly found in mineral oils. The percutaneous absorption of 14C-labeled anthracene, a three-ring PNA, was compared in a six-day in vivo and in vitro experiment with female Sprague-Dawley rats following a single topical dose (9.3 micrograms/cm2). In vivo absorption was measured by the presence of 14C radioactivity in urine, feces and tissues and in vitro absorption by penetration of radioactivity through excised skin into the receptor fluid of Franz-type diffusion cells. Several modifications of standard diffusion cell techniques were used which are known to enhance the absorption of lipophilic compounds. Anthracene was observed to readily penetrate the skin in both experiments and the total amounts absorbed in vivo and in vitro were seen to gradually coalesce over time. Within six days after application, 52.3 and 55.9% of the administered anthracene was absorbed in vivo and in vitro, respectively.