[Antitumor activities of orally administered 4-carbamoylimidazolium-5-olate (SM-108)]

We investigated the antitumor effect of orally administered SM-108. The drug showed strong antitumor activities against Ehrlich carcinoma, sarcoma 180, P388 leukemia, L1210 leukemia, colon 26 adenocarcinoma, colon 38 adenocarcinoma, and Lewis lung carcinoma. The antitumor activity of SM-108 against Ehrlich carcinoma was so remarkable, in fact, that all mice in a group survived for a long time. The antitumor effect of SM-108 depends on its administration schedule. Treatment involving a schedule of one dose every 6 h for 24 h at intervals of 3 days brought about a much stronger effect than daily single treatment. The maintenance of a high serum level of SM-108 for 24 h by the former treatment is responsible for the strong therapeutic effects, because the action of SM-108 is time-dependent. The antitumor activities of SM-108 administered orally are excellent enough to be comparable with those obtained by intraperitoneal administration as previously reported.