Effect of Cimetidine on the Absorption of Vitamin B₁₂

Abstract

The effect of Cimetidine on the absorption of orally administered crystalline or food (egg yolk-bound) vitamin B₁₂ (B₁₂) was studied in 13 patients. Absorption of crystalline B₁₂ was normal and not significantly changed by Cimetidine. In contrast, the uptake of food-bound B₁₂ decreased in all patients, from a mean of 5.3% without the drug to 2.5% after it, a fall of 53% (p < 0.0001). This impairment of B₁₂ absorption raises the possibility that long-term, full-dose therapy with Cimetidine may produce B₁₂ deficiency similar to that seen in other hypochlorhydric states. Our data indicate that cimetidine-induced B₁₂ malabsorption would not be detected by the standard Schilling test.

Key-words:

• Cimetidine
• vitamin B₁₂