Does ranitidine provide protection against acid gastroesophageal reflux?

Continuous gastroesophageal pH monitoring was used to evaluate the effect of ranitidine on gastroesophageal reflux (GOR) in 60 patients scheduled for elective non-gastrointestinal abdominal or gynaecological surgery. The patients were randomly assigned to receive a single dose of ranitidine 50 mg either iv (RANIV group) or im (RANIM group) or a placebo iv (PLAC group) 90 min before surgery. The pH was measured continuously for six hours in the lower oesophagus using a flexible calibrated glass electrode. A pH < 4.0 was chosen as the boundary for defining occurrence of acid GOR. Both ranitidine treatments reduced the total number of acid reflux episodes and the global reflux index (P < 0.05). The duration of the acid reflux episodes (sum of refluxes) and the number of acid reflux episodes longer than five minutes were markedly decreased by ranitidine but the mean duration of the reflux episodes was unaffected. The pH values at induction, intubation, surgical incision and extubation were similar in the PLAC and RANIV groups but more acid than in the RANIM group. The mean pH of reflux episodes was less acid in both ranitidine groups than in the PLAC group (P < 0.05). Also the number of very acid refluxes (pH < 2.5) decreased with ranitidine (P < 0.05). Intramuscular and intravenous administration of ranitidine provide protection against gastroesophageal reflux, with shorter duration of reflux episodes occurring in the intramuscular group. Regardless of the administration of ranitidine, protection against gastroesophageal reflux is incomplete; the frequency of reflux episodes is reduced but not eliminated.