Effect of cimetidine on the absorption of vitamin B12.
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 or 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 less than 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.
D000042:Absorption; D000328:Adult; D002927:Cimetidine / Q000009:adverse effects / Q000494:pharmacology*; D004530:Egg Yolk; D005260:Female; D006146:Guanidines / Q000494:pharmacology*; D006801:Humans; D008297:Male; D014805:Vitamin B 12 / Q000378:metabolism*; D014806:Vitamin B 12 Deficiency / Q000139:chemically induced
D006146:Guanidines; D002927:Cimetidine; D014805:Vitamin B 12