1982 Volume 102 Issue 10 Pages 978-983
The degradation rates of penicillins and cephalospolin C's in aqueous solution were found to be accelerated by the coexistence of sodium bisulfite (SBS). The action of SBS was recognized to be catalytic. The destructive actions of SBS on penicillin G, carbenicillin, methicillin and sulbenicillin were shown by comparatively small catalytic rate constants. The actions of SBS on ampicillin and cloxacillin were shown by one figure larger catalytic rate constants, i.e., catalytic rate constants for penicillin G and ampicillin were 4.47 M-1h-1 and 30.53 M-1h-1, respectively, at 60°C, pH 6.5 and μ=0.1. The degradations of cephaloridine and cephalothin were also remarkably accelerated by SBS. As the results of stability studies on ampicillin in solution, the action of SBS was shown to be largest at pH value of approximately 6.5 and pH-rate profile was known to be inverse to that of the straight solution of ampicillin, and the effects of temperature and the concentration of SBS on the actions were determined. By utilizing these data, a new practical approach by use of a nomograph was proposed to predict the stability of ampicillin in the admixture of the antibiotics with parenterals containing SBS as an additive.
