A randomized, multiple, cross-over, double-blind study was designed to compare the effects of three different regimens known to inhibit acid secretion.

Investigators measured intragastric 24-hour pH in 11 healthy subjects. Every participant was given four dose regimens randomly, for 2 weeks each. The treatment regimens included ranitidine 300 mg b.d., omeprazole 20 mg o.m., omeprazole 40 mg o.m., and placebo.

The findings revealed –

• Significantly greater reduction in gastric acidity during the daytime and during the entire 24-hour period with all three treatment regimens compared to placebo.
• A significant difference in acid inhibition between ranitidine and 40 mg omeprazole, but not between ranitidine and 20 mg omeprazole, nor between the omeprazole regimens.
• During the night-time, the reduction in gastric acidity by all three treatments was found to be significantly greater compared to that after placebo; no difference could be seen between the two doses of omeprazole and ranitidine.
• For the time of pH above 3, there was no statistically significant difference between the different treatment regimens.
• The pH remained significantly longer above 4 after ranitidine and the two omeprazole regimens compared to placebo. It remained longer above 4 with 40 mg omeprazole compared with ranitidine, but not after 20 mg omeprazole compared with ranitidine.

The median percentages of time for intragastric pH greater than 3 and pH above 4 are summarized in Table 1.

Table 1. Median value (percentage) of pH above 3 and 4

To conclude, treatment with 300 mg ranitidine b.d., omeprazole 20 mg or 40 mg appears to be better than placebo in gastric acid inhibition, when measured using 24-hour pH monitoring.

Source: Houben GM, Hooi J, Hameeteman W, Stockbrügger RW. Twenty-four-hour intragastric acidity: 300 mg ranitidine b.d., 20 mg omeprazole o.m., 40 mg omeprazole o.m. vs. placebo. Aliment Pharmacol Ther. 1995 Dec;9(6):649-54.