The change of the injecting agents on compounding was accompanied by their physical changes as well as, sometimes, marked chemical changes. Particularly, the stability of ascorbic acid (abbreviated as VC) in injecting preparations, which we have examined, has been reported by many authors.
On compounding the injecting agents, the main ingredient will be influenced by other ingredients, such as stabilizing agents, solubilizing agents, antiseptic agents, anocithetic agents, etc., which cause physical and chemical changes. When VC is diluted with a parenteral fluid, its stability is gradually lost with time and the change with time is greately influenced by the nature of the medium, pH, temperature, etc., thus 15 kinds of maketed parenteral fluids have been chosen and mixed with VC to examine the stability with time. The result will be reported here.
When VC and various parenteral fluids were mixed the VC content was seemed to be changed slightly with the change of pH, but as a whole, the change of pH was not so great within the time of measurement. The change of VC content was markedly different from product to product, and various conditions affecting on the content of VC are possible:
1. From the view point of pH value, the VC content was influenced by the change of pH values. The change of VC content with time after mixing was marked in the pH region lower than 5, and between pH 5 and 6, considerable change of VC content was observed but arround pH 7 or higher region VC was remained about 90% without destroying after 5 hours.
2. The decomposition is influenced by temperature, so that the VC content in summer and Winter will be considerably different.
3. Shaking with the parenteral fluid will be greately influenced. Thus more shaking will induce more VC decomposition.
4. VC injection is diluted with the parenteral fluids, so the stabilizing agent is also diluted.
As the result the effect of the stabilizer may be reduced, but it is difficult to conclude the result because ingredients in the parenteral fluids have to be taken into consideration.
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