1958 年 78 巻 4 号 p. 414-417
The metabolite of isonicotinoylhydrazide (INAH), first discovered by the present authors in 1953, is a Schiff base, isonicotinoylhydrazonopyruvic acid, and this was later found to have almost the same minimal inhibitive concentration against tubercle bacilli as that of INAH, while its toxicity was much weaker. This point was further endorsed by clinical tests and the compound has been commercialized.
The present paper discusses the question of the lowering of toxicity, which formed the basis for the use of isonicotinoylhydrazonopyruvic acid. As shown in Tables III and IV, the acute toxicity LD50 in mice is 3533mg./kg. of the sodium salt by subcutaneous injection and 1780mg./kg. by oral administration. This is 1/29 of that of INAH by parenteral route and 1/6.4 by the oral route.
In connection with this fact, it has experimentally been proved that INAH and pyruvic acid are antagonistic in the point of toxicity. It is interesting that the toxicity of the Schiff base is far weaker than that of the concurrent use of INAH and pyruvic acid.