Dextromethorphan and its analogues (DM 16, DM 34, DM 72, DM 75 and DM 96) were examined for their effect on Ehrlich
ascites carcinoma or
ascites sarcoma-180 in female mice of the ddY strain. The
suspension of Ehrlich
carcinoma cells or sarcoma-180 cells was prepared from mice
at 10 days after i.p. inoculation of the cells, using
Hanks' balanced salt solution, and the cell
suspension was inoculated i.p. into mice (2 X 10(6) viable cells/mouse). The chemicals dissolved in physiological saline containing 5% HCO-60 were then injected i.p. into the mice once daily for 5 successive days (5-40 mg/kg/day). In addition, mice given the
tumor cells were treated with the saline containing 5% HCO-60 alone for 5 days (untreated mice). In groups of mice bearing Ehrlich
ascites carcinoma or
ascites sarcoma-180, the mean survival time of mice treated with 20-40 mg/kg/day of DM 96 was more than twice that of the corresponding untreated mice. The mean survival time of mice treated with 20 mg/kg/day of DM 96 was also longer than that of mice treated with 40 mg/kg/day of the other chemicals, irrespective of the
ascites tumors. Concerning these survival times, the LD50 (i.p.) of DM 96 in mice differed slightly from that of other chemicals (88 mg/kg and 77-106 mg/kg). These results indicate that DM 96 is more active than the other chemicals against the
ascites tumors in mice.