Histamine-2-receptor antagonists in gastro-oesophageal reflux.

Histamine-2-receptor antagonists in gastro-oesophageal reflux While the widespread use of histamine-2-receptor antagonists (H2RA) in reflux oesophagitis can be justified by the results of clinical trials, they are not effective in all cases. Gastro-oesophageal reflux disease (GOR) results from prolonged contact time of refluxed noxious agents (especially acid) with the mucosal surface cells in the distal oesophagus. It may also result from impaired mucosal defences such as alteration in the mucus layer. Prolonged contact because of poor oesophageal clearance is also a factor in some cases, notably systemic sclerosis. The frequency and volume of refluxed fluid is important, being determined by gastric contents and the competence of the anti-reflux mechanism. Finally the composition of the refluxate is central, especially the concentration of gastric acid, possibly with pepsin and bile influencing its damaging effect. H2RAs can only reduce the concentration of acid and possibly the volume of fluid that refluxes. This may be sufficient to induce symptomatic relief and promote healing, especially in the milder cases, but as only one of several factors responsible for GOR is affected by H2RAs, it is not surprising that not all cases respond. This review examines the role of H2RAs in reflux oesophagitis at a time when newer treatments enable the clinician to manipulate gastric acidity and upper gastrointestinal motility more effectively.