Not to be given in patients w/ suspected vit B12 deficiency w/o 1st confirming diagnosis. Monitor blood regularly. Dose >10 mcg daily may produce hematological response in patients w/ folate deficiency. Leber's disease or tobacco amblyopia.
Reduced absorption of vit B12 from the GIT w/ neomycin, aminosalicylic acid, histamine H2-antagonists, omeprazole & colchicine. Serum conc may be decreased w/ OCs. Parenteral chloramphenicol may attenuate the effect of vit B12 in anemia.