Some cytostatic and pharmacological properties of 2,3-dihydro-1,3-6H-oxazine-2,6-dione ("3-oxauracil").

Cytostatic effects and some pharmacological properties of a new metabolic inhibitor "3-oxauracil" were studied. The cancerostatic effect was examined on 7 experimental tumors in mice and on two types of tumors in rats. After the i. p. application of 20 mg/kg, there was both a statistically significant decrease of tumor weight and increase of animals' survival time in NK lymphoma of mice. Significant changes in one of both parameters followed occured in all experimental tumors after the i. p. application but only in the Krebs ascitic carcinoma after the oral application of "3-oxauracil". The acute toxicity of the substance in water was 322 mg/kg i. p. and 850 mg/kg p. o. The ethanol solutions were more toxic. The distribution of the 3H- and 14C-labeled substance was followed up in blood, urine, liver, brain and kidney. After the p. o. application, the radioactivity peak was reached after 2 hr in blood and high radioactivity levels were found in kidney followed by brain and liver. 96 hr after the drug was applicated perorally, only 60% of radioactivity was found in urine.