Oral epidermal carcinoma

Mild hepatotoxicity and nephrotoxicity have been observed in rats exposed to PAHs. Intraperitoneal administration of BP to rats produced an immediate and sustained reduction in growth rate of young rats. A single topical exposure of BP in acetone increased the mitotic rate of epidermal cells. Single oral administration of 100 mg BP to 50-day-old Sprague-Dawley rats produced mammary tumors. Single intraperitoneal administration of 10 mg BP produced two mammary and two uterine carcinomas among 10 Wistar rats within 1 year. 

Vitamin A deficiency is characterized by squamous metaplasia of a variety of epithelia with increased cell proliferation and hyperkeratosis. These changes are also features of some benign dermatoses, for example, psoriasis. Once beneficial effects of oral vitamin A were observed, its use spread to the treatment of other diseases of the epidermis and epidermal appendages, including acne, psoriasis, and basal cell carcinoma. Since the hypervitaminosis A syndrome (see Chapter 13) interfered with long-term therapy with vitamin A, the need arose for synthetic derivatives that could be at least as efficacious as vitamin A and yet be less toxic. The use of isotretinoin and etretinate, as described above, represents the first development of this concept in clinical practice. 

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