The Antisecretory Effects of Ranitidine Administered by Continuous Infusion

Abstract

Prevention of stress-induced upper gastrointestinal ul ceration and bleeding is an important issue for clinicians caring for critically ill patients. Although H2 blockers have been demonstrated as effective in treating patients with stress ulcers and bleeding, the ideal regimen of administration has not yet been devised. One method, continuous intravenous infusion, minimizes variation in drug effects by controlling for pharmacokinetic vari ables. Even with the use of continuous infusion, consis tent control of gastric pH may not be attained. Because of the pharmacokinetic, pharmacodynamic, and patient variables, there is often a discrepancy between H2 blocker dose and effects. Studies in healthy persons and patients with duodenal ulcers demonstrate a circadian variation in gastric acid production and in the effects of H2 blockers on gastric pH. In particular, H2 blockers may be less effective in the evening. To address this concern in intensive care patients, continuous intrave nous infusions of H2 blockers can be used, but variable rates of intravenous infusions may be more effective, allowing for the circadian variations in gastric acidity. Further study is needed to define patient groups that most require intravenous H2 blockers, to devise regi mens that are more effective in continuously controlling gastric pH in critically ill patients, and to clarify dose- response relationships for H2 blockers.