Oral griseofulvin: a cocarcinogenic agent to methylcholanthrene induced cutaneous tumors.

Since certain antitumor drugs also arrest mitosis in metaphase, an attempt was made to determine the effect of oral griseofulvin on methylcholanthrene-induced cutaneous tumors in mice. Contrary to expectations, mice on large doses (1000-1500 mg/kg) of griseofulvin subjected to methylcholanthrene applications had a shorter tumor lag period and developed more and larger tumors than did mice not receiving griseofulvin but receiving similar amounts of methylcholanthrene. A cocarcinogenic effect was also noted in mice that received lower doses (10-15 mg/kg) of griseofulvin for 6 weeks prior to, during, and subsequent to methylcholanthrene applications, but not in mice that received this dosage for 4 weeks prior to, during, and subsequent to methylcholanthrene application.