A study by Maltby et al compared the effect of oral ranitidine alone with sequential administration of ranitidine, metoclopramide, and sodium citrate on gastric fluid volume and pH in 196 healthy, elective surgery patients. Each of the patients was randomly assigned to one of the four groups.

Patients in all groups were given oral ranitidine 150 mg 2-3 hr prior to surgery. Patients in Group 1 were also given oral metoclopramide 10 mg an hour before surgery, besides receiving sodium citrate 0.3 M 30 ml on call to the operating room. Group 2 patients were given sodium citrate but no metoclopramide. Patients in Group 3 received metoclopramide but no sodium citrate and those in Group 4 received only ranitidine. After induction of anesthesia, gastric fluid was aspirated and volume and pH were measured.

• In all the groups mean pH was > 5.8.
• Mean volumes were significantly higher in patients in Groups 1 and 2 compared to Groups 3 and 4.
• No significant differences were evident among groups either in pH values or in the number of patients with gastric pH < 2.5 or number of patients with pH < 2.5 and volume >25 ml.
• One patient in Group 2 and one in Group 3 had pH < 2.5 with volume > 25 ml.

The study revealed that there appears to be no benefit of double or triple prophylaxis over ranitidine alone.

A single oral dose of ranitidine 150 mg 2-3 hr before surgery is as clinically effective as triple prophylaxis.

Source: Maltby JR, Elliott RH, Warnell I, et al. Gastric fluid volume and pH in elective surgical patients: triple prophylaxis is not superior to ranitidine alone. Can J Anaesth. 1990;37:650-5.