Metabolism and disposition studies of 9-hydroxyellipticine and 2-methyl-9-hydroxyellipticinium acetate in animals.

Radiolabeled 9-hydroxyellipticine (iv and ip routes) and the corresponding radioactive quaternary salt, 2-methyl-9-hydroxyellipticinium acetate (iv route), were administered to mice. Tissue distribution was then followed up to 64 hours by means of autoradiography. Both drugs accumulated in the kidneys, lungs, and liver; 9-hydroxyellipticine also accumulated in the spleen and bone marrow. The quaternary salt was concentrated in the gastrointestinal walls and the salivary and thyroid glands; none was found in the brain. Metabolic studies after administration of these antitumor drugs to rats and mice showed that 9-hydroxyellipticine is extensively metabolized, mainly to its glucuronide. Under our experimental conditions, the ellipticinium derivative was excreted unchanged in the bile (70%) and in the urine (30%). Pharmacokinetic studies in mice using either radioactivity measurements or selective extraction followed by spectrofluorometric quantitation have shown that blood levels drop very rapidly during the distribution phase followed by a much slower disposition phase, with a half-life of about 30 hours for the quaternary salt.