Lack of clinically significant in vitro and in vivo interactions between ranitidine and sucralfate

The hypothesis that the cytoprotective agent sucralfate (sucrose octakis(hydrogen sulfate)-aluminum complex) interacts with the H2-antagonist ranitidine (N-[2-[[dimethylamino)methyl]furfuryl]- thio]ethyl]-N'-methyl-2-nitro-1,1-ethenediamine) by decreasing ranitidine absorption was tested in vitro and in vivo. The in vitro results show that ranitidine may bind to a small extent (approximately 10%) to sucralfate paste in the gastrointestinal fluids. The in vivo ineraction of 150 mg of ranitidine and 1 g of sucralfate was evaluated in a crossover study in six healthy volunteers. The results indicate no significant difference in pharmacokinetic parameters when ranitidine was given alone and in combination with sucralfate. Thus, ranitidine bioavailability is not diminished by sucralfate and the two drugs can be given concomitantly. For the determination of bioavailability, it has to be taken into account that renal clearance of ranitidine is lower after oral than after intravenous administration, and that enterohepatic recirculation of the drug is likely.