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Clinically, Vitamin C and Vitamin B6 are often used together to treat conditions such as fever and diarrhea. In recent years, reports have emerged regarding adverse reactions when these two are used in combination, leading to claims of incompatibility. What is the truth behind this?
No solid evidence of incompatibility
The adverse reactions associated with the combined use of Vitamin C and Vitamin B6 can be attributed to various factors, including the patient population, drug dosage, and infusion rate, but this does not indicate that there is an incompatibility between the two.Physical incompatibility refers to changes in solubility, appearance, and other physical properties when certain drugs are mixed, leading to common phenomena such as separation, precipitation, deliquescence, and liquefaction. Chemical incompatibility occurs when certain drugs react with each other, altering their properties, which can reduce efficacy, cause failure, or enhance toxicity, resulting in changes such as discoloration, gas production, precipitation, hydrolysis, combustion, or explosion.There have been no physical or chemical changes observed when Vitamin C and Vitamin B6 are used together, indicating that the product inserts do not explicitly state any incompatibilities, and the “Common Drug Incompatibility Table” does not contain relevant information.
Is the combination of Vitamin C + Vitamin B6 reasonable?
The combined use of Vitamin C injection and Vitamin B6 injection may increase the risk of adverse reactions. From January 1, 2016, to December 31, 2019, the Yunnan Province Adverse Drug Reaction Monitoring System reported 410 cases of adverse reactions/events related to Vitamin B6 injection, of which 282 cases were reported in conjunction with Vitamin C injection[1].Vitamin C has strong reducing properties, while Vitamin B6 is an amphoteric compound with greater oxidizing properties than reducing properties. When used together, a reaction may occur where Vitamin C reduces Vitamin B6, causing it to lose its therapeutic effect. Literature has reported that although the infusion of the two injection solutions is relatively stable in terms of insoluble particles and appearance, the pH of the mixed solution exceeds the range specified by the pharmacopoeia, which may reduce the stability of the drug during infusion[2].For safety reasons, we recommend that Vitamin C injection and Vitamin B6 injection be administered separately whenever possible.
Overview of incompatibilities[3,4]
Vitamin C: Its combination with salicylates and barbiturates can increase excretion, while combinations with Vitamin K3, Vitamin B2, alkaline drugs, and iron ions can reduce efficacy and should be avoided. It should not be mixed with alkaline drugs (such as sodium bicarbonate), Vitamin B12, or Vitamin K3 solutions for injection, as it is prone to oxidation and loss of efficacy. It has varying degrees of inactivation effects on aminoglycosides, β-lactams, tetracyclines, and other antibiotics, so it should not be mixed with these antibiotics for injection. High doses can acidify urine, increasing the excretion of certain organic alkaline drugs.Vitamin B6: Chloramphenicol, cycloserine, isoniazid, hydralazine, corticosteroids, cyclophosphamide, cyclosporine, isoniazid, and other drugs can antagonize Vitamin B6 or increase its renal excretion, potentially leading to anemia or peripheral neuropathy.
Q
How to distinguish the “remarkable” vitamin family?
References:
[1] Yin Yuanyuan, Huo Hongyan, Yu Ping. Analysis of 410 cases of adverse reactions to Vitamin B6 injection [J]. Journal of Kunming University, 2021, 43(03):119-124.
[2] Yang Jinyuan, Gan Meichan, Hu Mingliang, et al. Stability analysis of commonly used multi-drug infusion combinations in hospitals. 2022, Vol. 17, No. 4:109-112.
[3] Vitamin C injection instructions.
[4] VitaminB6 injection instructions.
