Transition of Products From Prescription to Over the Counter: The H2 Antagonists

In general, the histamine type-2 receptor antagonists (H 2 RA) enjoy an enviable record of safety. These agents, notably cimetidine, have been studied extensively in clinical trials, case reports, and worldwide drug use reporting systems. Of the available agents (cimetidine, famotidine, nizatidine, and ranitidine) several similarities exist from compound to compound and use data to support that each of the agents is equally safe and efficacious in equipotent dosing. A review of H 2 RA pharmacology, pharmacokinetics, adverse effects, and drug interactions is included to provide the clinician with a basis for rational selection and use of an H 2 RA.