The adverse effect profile of
proton-pump inhibitors is presented. The
proton-pump inhibitors are a well-tolerated class of drugs. The most common adverse events of
headache,
diarrhea, and
nausea have been reported in fewer than 5% of patients treated with
lansoprazole or
omeprazole. The frequency of these adverse events with the two
proton-pump inhibitors is comparable to that of placebo and
histamine H2-receptor antagonists. Few clinically important interactions have been observed between
proton-pump inhibitors and other drugs metabolized by the
cytochrome P-450 system. The interaction potential should be considered when drugs with a narrow therapeutic window, such as
phenytoin,
warfarin, and
theophylline, are used concomitantly with
proton-pump inhibitors. Theoretical concerns about the consequences of chronic administration of
proton-pump inhibitors, such as the impact of sustained hypergastrinemia on gastric morphology and the development of
atrophic gastritis, have been dismissed. While increased
gastrin levels are observed among patients taking
proton-pump inhibitors, for the majority they remain within the normal range. After long-term use of the drugs, patients do not appear to be at increased risk of
atrophic gastritis or
gastric cancer. Helicobacter pylori
infection, rather than
acid suppression, may be the more important factor for the development of
atrophic gastritis. Bacterial overgrowth and altered nutrient absorption resulting from sustained
hypochlorhydria induced by chronic administration of
proton-pump inhibitors have not been realized as clinical concerns. Not only are
proton-pump inhibitors well tolerated during short-term administration, but there also do not appear to be clinically important adverse sequelae associated with their long-term use.