Action

MUTAMYCIN (mitomycin) selectively inhibits the synthesis of deoxyribonucleic acid (DNA). The guanine and cytosine content correlates with the degree of MUTAMYCIN (mitomycin) -induced cross-linking. At high concentrations of the drug, cellular RNA and protein synthesis are also suppressed.

In humans, MUTAMYCIN (mitomycin) is rapidly cleared from the serum after intravenous administration. Time required to reduce the serum concentration by 50% after a 30 mg bolus injection is 17 minutes. After injection of 30 mg, 20 mg, or 10 mg I.V., the maximal serum concentrations were 2.4 µg/mL, 1.7 µg/mL, and 0.52 µg/mL, respectively. Clearance is effected primarily by metabolism in the liver, but metabolism occurs in other tissues as well. The rate of clearance is inversely proportional to the maximal serum concentration because, it is thought, of saturation of the degradative pathways.

Approximately 10% of a dose of MUTAMYCIN (mitomycin) is excreted unchanged in the urine. Since metabolic pathways are saturated at relatively low doses, the percent of a dose excreted in urine increases with increasing dose. In children, excretion of intravenously administered MUTAMYCIN (mitomycin) is similar.

Animal Toxicology

MUTAMYCIN (mitomycin) has been found to be carcinogenic in rats and mice. At doses approximating the recommended clinical dose in man, it produces a greater than 100% increase in tumor incidence in male Sprague-Dawley rats, and a greater than 50% increase in tumor incidence in female Swiss mice.

Last reviewed on RxList: 10/24/2008
This monograph has been modified to include the generic and brand name in many instances.