A nasal spray formulation of cyanocobalamin (Nascobal – Questcor) has been approved by the FDA for maintenance treatment of vitamin B12 deficiency. Nascobal is already available as an intranasal gel. Vitamin B12 deficiency, diagnosed by elevated serum concentrations of methylmalonic acid with or without elevated serum homocysteine and low serum B12 concentrations (<200 pg/mL), is common in older patients.1Since intestinal absorption of B12 may be impaired, the usual maintenance treatment of deficiency is intramuscular injection of the vitamin in doses of 1 mg every 4 weeks (after more...