Attack of cefotaxime by different radicals: comparison of the effects.

Free radicals are physiological products and can react to administrated drugs. Metabolic transformations by radical mechanisms are, therefore, possible. A fundamental study of radio-induced degradation of aqueous solutions of sodium cefotaxime, a third generation cephalosporin, was realized to describe these possible radical mechanisms. Different radicals produced by the radiolysis method (.OH, N3., Br2.-, Tbut., eaq- + .OH, and exq- + Tbut.) were successively used to induce the radical mechanisms and their effects were compared. All these radicals induce the formation of a same main radiolysis product identified as anticefotaxime. Radical mechanisms induced by N3., Tbut., and eaq- include chain reactions to explain the formation of anticefotaxime contrary to those induced by .OH and Br2.-.

Radical mechanisms of cephalosporins: a pulse radiolysis study.

Radiosterilization induces radicals, and it is very important to describe radical mechanisms before the possible use of cephalosporins gamma sterilization. Moreover, physiological or radiotherapeutically induced free radicals also initiate radical mechanisms. For this study, pulse radiolysis was used. This method permits to avoid in vivo direct study difficulties of bioradical processes and gives quantitative data. Reactions of solvated electron (eaq-), hydroxyl radical (.OH), azide radical (N3.), dibromine radical anions (Br2.-), oxygen, and superoxide radical (O2.-) with three cephalosporins have been studied. Absorption spectra and rate constants have been determined. It has been found that both eaq- and .OH quickly react (k congruent to 10(10) mol-1 L s-1) with the molecules to give radicals with similar absorption spectra. N3. gives an absorption spectra that has been attributed to an electron transfer, whereas a part of .OH and Br2.- could add themselves to an unsaturated bond.