Review article: drug interactions with agents used to treat acid-related diseases

Patients with acid-related diseases often need to take multiple medications . Treatment of Helicobacter pylori infection often includes either a histam ine type 2 (H-2)-receptor antagonist or a proton pump (H+,K+-ATPase) inhibi tor (proton pump inhibitor), administered in conjunction with one or more a ntimicrobials. Also, treatment for acid-related diseases often requires ext ended therapy during which many concomitant medications may be administered for concurrent disease states. Polypharmacy may be the result, particularl y in elderly patients, who are at increased risk for both acid-related and many other diseases. Thus, it is important to understand the potential for clinically significant drug-drug interactions in this setting. H-2-receptor antagonists and proton pump inhibitors can influence the pharmacokinetic p rofiles of other commonly administered medications by elevating intragastri c pH, which can alter drug absorption, and by interacting with the cytochro me P (CYP) 450 enzyme system, which can affect drug metabolism and clearanc e, Such interactions are particularly important when they affect the pharma cokinetics of drugs with narrow therapeutic ranges (e.g. warfarin, digoxin) . In these cases, drug-drug interactions can result in significant toxicity and even death. There are marked differences among H-2-receptor antagonist s and proton pump inhibitors in their potential for such interactions. The oldest drugs in each class. cimetidine and omeprazole, respectively, have t he greatest potential to alter CYP activity and. change the pharmacokinetic s of other drugs. The most recently developed H-2-receptor antagonist, famo tidine, and the newer proton pump inhibitors, rabeprazole and pantoprazole, are much less likely to induce or inhibit CUP and thereby change the metab olism of other medications. These differences are important when. choosing medications for the safe treatment of patients with acid-related diseases.