Role of the intestinal flora in the metabolism of misonidazole

The radiation sensitizer misonidazole is metabolized to its amino derivative [1-(2-aminoimidazol-1-yl)-3-methoxypropan-2-o1] in pure or mixed cultures of the intestinal microflora. This metabolite appears in the excreta of conventional rats but is not detectable in the excreta of germfree rats. Thus. its formation appears to be due to the activity of the intestinal flora in vivo as well as in vitro. CO₂ is liberated from 1(2aminoimidazol1yl)3methoxypropan2o1 by pure and mixed cultures of the In cultures of Clostridium perfringens that lack urease, the release of CO₂ depends on added urease, suggesting that urea is an intermediate in this pathway.