Tagamet is Cimetidine, which is not a Proton Pump Inhibitor (like rabeprazole), but an H2 receptor antagonist
The data on PPI's and benzodiazepines is extremely mixed, and often contradictory
Omeprazole is, certainly, a cytochrome inhibitor, and, as such, theoretically could be used to potentiate benzodiazepines such as diazepam
, and flunitrazepam
However, there is some debate as to whether this interaction results in clinically significant effects
Long term Lansoprazole use does not effect the metabolism of diazepam
(Influence of lansoprazole treatment on diazepam plasma concentrations.
Clin Pharmacol Ther. 1992 Nov;52(5):458-63.
Lefebvre RA, Flouvat B, Karolac-Tamisier S, Moerman E, Van Ganse E)
Similarly, Pantoprazole does not interact with diazepam
(Lack of pharmacokinetic interaction of pantoprazole with diazepam in man
Gugler R, Hartmann M, Rudi J, Brod I, Huber R, Steinijans VW, Bliesath H, Wurst W, Klotz U. Br J Clin Pharmacol. 1996 Aug;42(2):249-52.)
I have no information on Rabeprazole (and, neither, it seems, does pubmed, from a quick search this morning)