Prostatic atrophy in dogs after intravenous administration of a ureido-ethylimidazoline derivative (CGP15'720A).

1-(2-[4-Pridyl)-2-imidazoline-1-yl]-ethyl)-3-(4-carboxyphenyl)urea (CGP15'720A) is an experimental antineoplastic agent with marked activity against carcinogen-induced lung tumors in Syrian hamsters and human lung tumor xenografts in nude mice. A preclinical toxicity study of this agent was carried out in mice and dogs which demonstrated the relatively nontoxic nature of the agent. In mice, single intraperitoneal dosage of 12 g/m2 did not produce lethality; however, lethality (30% of treated mice) was seen during treatment with 6 g/m2 daily for 5 days. No hematological, serum-chemistry or histopathological changes were detected in mice after single or five consecutive treatments with 12 g/m2. Dogs were treated with doses ranging from 5 g/m2 to 80 g/m2, with deaths occurring in a non-dose-related fashion after 10, 20, and 40 g/m2. Acute neurological toxicity after infusion was the dose-limiting toxicity in dogs. There were no consistent hematological or serum-chemistry aberrations in the treated dogs. The most consistent histopathological finding was prostatic atrophy, which was detected in 5/12 dogs in this series.