The effect of ranitidine on the absorption of food cobalamins.

The effect of the histamine H2-receptor antagonist ranitidine on the absorption of food cobalamins was investigated in 20 healthy volunteers randomized to treatment with ranitidine or placebo for 1 week. Liver homogenates containing cobalamins labelled in vivo with cobalt-57 was obtained by repeated injections of 57Co-labelled cyanocobalamin in rabbits. Test doses (0.37 nmol) of the 57Co-labelled liver cobalamins were administered orally together with 51CrCl3 and carmine red, and the absorption of 57Co-labelled cobalamins was assessed from the ratio of the two isotopes in the stool collection that had been coloured by the carmine red. There was no significant difference in the mean absorption before (47.4%) and after (50.7%) the treatment.