Vitamin B12 Injection 100mcg/ml (Cyanocobalamine) comes in a multi-dose vial. The 10ml size of this vial contains the equivalent of ten 1ml weekly injections. CYANOCOBALAMIN (Vitamin B12) is a synthetic (man-made) form of vitamin B12. Naturally occurring vitamin B12 is found in fish, seafood, milk, egg yolk and fermented cheeses. Vitamin B12 is essential to the development of healthy blood cells, nerve cells, and proteins in the body and for the normal metabolism of fats and carbohydrates in the body.