Compatibility of penicillin and ascorbic acid injection.

The stability of Potassium Penicillin G, USP, when mixed with Ascorbic Acid Injection, USP, in 5% Dextrose Injection, USP, was studied. The change in concentration over an eight-hour period of potassium penicillin G in the admixture was determined by the hydroxylamine colorimetric assay method and the microbiological assay method. The stability of penicillin was not adversely affected by the presence of sodium ascorbate. Reports of incompatibilities between penicillin and ascorbic acid are a function of pH rather than a characteristic of the ascorbate ion. Articles reporting studies involving ascorbic acid should specify whether the work refers to the use of ascorbic acid or Ascorbic Acid Injection, USP. Confusion in the literature could be reduced by changing the official title from Ascorbic Acid Injection to Sodium Ascorbate Injection.