Cyanocobalamin side effects
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Cyanocobalamin Side Effects: An Overview
Introduction to Cyanocobalamin
Cyanocobalamin, a synthetic form of Vitamin B12, is essential for maintaining healthy nerves and blood cells and plays a crucial role in DNA synthesis. It is commonly used to treat Vitamin B12 deficiency, which can lead to conditions such as megaloblastic anemia, characterized by fatigue and weakness . However, despite its benefits, cyanocobalamin can have side effects, some of which are rare but potentially serious.
Anaphylactic Reactions to Cyanocobalamin
Rare but Serious Hypersensitivity
Anaphylactic reactions to cyanocobalamin, though uncommon, are serious and potentially life-threatening. These reactions can occur due to an immunoglobulin E (IgE)-mediated response or sensitization to the Vitamin B12 molecule itself. Several case reports have documented instances of severe anaphylactic reactions following intramuscular injections of cyanocobalamin 134. For example, a 25-year-old female patient with pulmonary tuberculosis experienced an anaphylactoid reaction after receiving a cyanocobalamin injection . Similarly, a 55-year-old woman developed an anaphylactic reaction after her second dose of intramuscular cyanocobalamin . These cases highlight the need for healthcare providers to be vigilant when administering cyanocobalamin, especially via the parenteral route.
Toxicity from High Doses
Symptoms of Overdose
Excessive intake of cyanocobalamin can lead to toxicity, although such cases are rare. A young woman treated with multiple daily doses of 1 mg of cyanocobalamin for severe pernicious anemia developed symptoms such as acne, palpitations, anxiety, akathisia, facial ruddiness, headache, and insomnia after a total dose of 12 mg. These symptoms subsided two weeks after discontinuing the drug, indicating that while cyanocobalamin toxicity is unusual, it is possible and should be monitored .
Impact on Renal Function
Potential Harm in Patients with Impaired Renal Function
Cyanocobalamin can accelerate the decline in renal function and increase the risk of cardiovascular events in patients with impaired renal function. Studies have shown that high-dose cyanocobalamin does not benefit patients with impaired renal function for stroke prevention and may even be harmful. Conversely, patients with normal renal function may benefit from B vitamin therapy, suggesting that the form of Vitamin B12 used in treatment should be carefully considered .
Cytotoxicity in Cell Studies
Antagonistic Effects and Cell Death
Research has shown that cyanocobalamin [c-lactam], a derivative of cobalamin, can antagonize Vitamin B12 and cause cytotoxicity in HL60 cells. This cytotoxic effect is reversible with additional Vitamin B12 and can be completely protected against by methionine. These findings suggest that cyanocobalamin [c-lactam] impairs critical cellular processes, leading to cell death from methionine deficiency .
Conclusion
While cyanocobalamin is an effective treatment for Vitamin B12 deficiency, it is not without risks. Anaphylactic reactions, toxicity from high doses, potential harm to renal function, and cytotoxic effects in cell studies underscore the importance of careful administration and monitoring. Healthcare providers should be aware of these potential side effects to ensure the safe use of cyanocobalamin in their patients.
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