Cimetidine is a non-specific
enzyme inhibitor and therefore interacts with a number of cytochrome P450 substrates. Other
H2-receptor antagonists do not have enzyme- inhibitory effects and therefore do not interact in this way. They may therefore provide useful alternatives to
cimetidine. However, note that if an interaction occurs due to an alteration in gastric pH, all
H2-receptor antagonists would be expected to interact similarly.