A randomized, double-blind, placebo-controlled, five-way crossover study was conducted to compare the effects of low doses of ranitidine and cimetidine on gastric pH and esophageal acid exposure.

The study included 20 healthy individuals who underwent gastric and esophageal pH monitoring using two glass pH electrodes, after placebo and single doses of ranitidine 75mg and cimetidine 200mg (in both effervescent and tablet forms), for 4h prior to and after a meal.

Findings from the study -

• During fasting, median gastric pH was found to increase significantly with both the drugs.
• Esophageal acid exposure was significantly reduced with all drug regimens.
• After a meal, there appeared to be no significant difference in gastric pH levels; however, there was a significant reduction in esophageal acid exposure with both forms of ranitidine, compared with placebo (P <0.05), and also with ranitidine tablets when compared with cimetidine tablets (P <0.05).

Conclusion -

• Low doses of ranitidine and cimetidine seem to increase gastric pH, with ranitidine having a more prominent effect.
• Ranitidine is associated with a more prolonged effect in comparison with cimetidine and reduces esophageal acid exposure, assessed following a meal taken 4h after the drug administration.

Source: des Varannes SB, Duquesnoy C, Mamet JP, et al. Effects of tablet and effervescent formulations of ranitidine 75 mg and cimetidine 200 mg on gastric acidity and oesophageal acid exposure in healthy humans. Aliment Pharmacol Ther. 1998;12:1155-61.