Intranasal vitamin B₁₂ administration in elderly patients: A randomized controlled comparison of two dosage regimens

Vitamin B₁₂ deficiency is common in the elderly population. Standard treatment via intramuscular injections, however, has several disadvantages. Safer and more convenient dosage forms such as intranasal are therefore being explored. This study compares the effects of two intranasal vitamin B₁₂ dosage regimens in elderly vitamin B₁₂-deficient patients.

Sixty patients ≥65 years were randomly assigned to either a loading dose (daily administration for 14 days followed by weekly administration) or a no loading dose (administration every 3 days) regimen for 90 days. Each dose contained 1000 μg cobalamin. Total vitamin B₁₂, holotranscoblamin (holoTC), methylmalonic acid (MMA) and total homocysteine (tHcy) levels in serum were measured on days 0, 7, 14, 30, 60 and 90.

Both dosage regimens resulted in a rapid increase of vitamin B₁₂ and holoTC concentrations and normalization of initial high, MMA and tHcy concentrations. The loading dose regimen resulted in the fastest and greatest increase to a median vitamin B₁₂ of 1090 pmol/L (reference 350-650 pmol/L) concentration after 14 days. Following weekly administration, B₁₂ rapidly decreased to a median concentration of 530 pmol/L after 90 days. The no loading dose regimen resulted in a steady increase to a median vitamin B₁₂ of 717 pmol/L after 90 days.

Intranasal vitamin B₁₂ administration is an effective and suitable way to replenish and sustain vitamin B₁₂ levels in elderly patients.