Vitamin B12, also known as cobalamin, antipernicious - anemia factor, Castle’s extrinsic factor, or animal protein factor is the largest and most complex of all the vitamins. It is necessary for the formation of blood cells, nerve sheaths and various proteins. It is also involved in fat and carbohydrate metabolism. It is also essential for DNA synthesis, for cellular energy production and growth. Vitamin B12 is also required in the synthesis of folate polyglutamates (active co-enzymes required in the formation of nerve tissue) and in the regeneration of folic acid during red blood cell formation. Evidence indicates methylcobalamin is utilized more efficiently than cyanocobalaminto increase levels of one of the coenzyme forms of vitamin B₁₂. Experiments have shown similar absorption of methylcobalamin & cyanocobalamin following oral administration. Also, the quantity of cobalamin detected following a small oral dose of methylcobalamin is similar to the amount following administration of cyanocobalamin; but significantly more cobalamin accumulates in liver tissue following administration of methylcobalamin. The treatment of choice for cobalamin deficiency has been the administration of cobalamin by intramuscular injections. In case of oral supplementation, approximately only 1% of ingested B₁₂ is absorbed via the gastrointestinal tract requiring IF factor and other transport proteins for proper absorption. So requirement of high doses and co transporters limit the use of oral cobalamin form. Nasal Methylcobalamin therapy has been recently introduced as an innovative route for the systemic availability of B12 due to the large surface area, porous endothelial membrane, high total blood flow, the avoidance of first-pass metabolism, and ready accessibility of the route. Methylcobalamin is absorbed rapidly, safely and consistently from the nasal cavity after intranasal administration. Further, intranasal formulation has overcome the drawbacks of intramuscular formulation.