The National Medicines Safety Agency is warning of a shortage of vitamin B12 in injectable and oral solution in city pharmacies, a situation which is expected to last until the beginning of 2025. Therefore, it recommends using vitamin B12 in tablets if possible in order to reserve injectable solutions from the Zentiva and Substipharm laboratories for patients who need to be treated intramuscularly. “This will allow patients who require intramuscular vitamin B12 injections to continue their treatment. The absence of this treatment can lead to a serious risk of anemia in these patients, leading to hospitalization, transfusion and life-threatening consequences. explains the ANSM.
Why is vitamin B12 essential to our body?
Vitamin B12, bright red in color, contains cobalt, hence its other name colobamine. It is necessary for the formation and maturation of red blood cells, as well as for the synthesis of DNA, the genetic material of cells. It is also important for nerve function. In food, it is only found in foods of animal origin.
A vitamin B12 deficiency leads to anemia responsible for many symptoms including fatigue, extreme paleness, weakness, shortness of breath and dizziness in severe cases. Severe deficiency can cause nerve damage, tingling or loss of sensation in the extremities, muscle weakness, loss of reflexes, motor difficulties, confusion and dementia.
In which cases should vitamin B12 (cyanocobalamin) be administered by intramuscular injection?
Vitamin B12 deficiency can be linked to an inadequate diet, especially as part of a strict vegan or vegetarian diet. Indeed, the main sources of vitamin B12 are mainly of animal origin: meat, fish, milk. For vegans, oral intake is possible. Just like in Crohn's disease, celiac disease, certain bariatric surgeries, HIV…
Other patients can only benefit from vitamin B12 by intramuscular injection. These present “serious absorption problems”. Normally, this vitamin is easily absorbed in the last part of the small intestine, leading to the large intestine. But it must be linked to a protein produced in the stomach, called intrinsic factor, to achieve this. Otherwise, the vitamin progresses through the intestine and is excreted in the feces.
Among the causes, we find:
- Biermer's disease: also called pernicious anemia, this is a chronic autoimmune disease that affects the stomach. The immune system attacks the cells in the stomach wall, responsible for the production of the protein called intrinsic factor, which is essential for the absorption of vitamin B12 in the intestine.
- A total gastrectomy: Gastrectomy is the surgical removal of the stomach. It is practiced in particular to treat cancer which has spread to the entire stomach or two thirds. Deprived of a stomach, the body no longer produces the intrinsic factor necessary for the absorption of vitamin B12. Supplementation, by intramuscular injection, is then essential for life.
- Terminal ileum resection: the ileum is the site of absorption of vitamin B12 by the small intestine. Depending on the size of the intestine removed, short bowel syndrome may occur, the intestine may then lose its vitamin B12 absorption function, injections are then essential.
- Imserlund's disease due to Imerslund-Grasbeck syndrome: or selective cobalamin (vitamin B12) malabsorption is characterized by a vitamin B12 deficiency, a disorder that appears in childhood.
Source: ANSM, MSD Manual, Inca
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