Ranitidine is a histamine-2-antagonist (H2 receptor antagonist), which has potential role in the inhibition of intragastric acidity.1

Based on the hypothesis that combined use of an effervescent antacid and ranitidine could be associated with immediate and lasting increase intragastric acidity, a study was conducted to evaluate the effect of the combined intake of low dose ranitidine and 5 g of antacid on gastric pH.

The study included 20 healthy Helicobacter pylori negative individuals. A fasting 6-hour gastric pH-metric procedure was done at two different occasions – at baseline (1 hour before drug administration) and post-drug (5 hours after oral administration of a single dose of ranitidine (75 mg) with 5 g of an antacid. A total of 18 subjects were finally evaluated.

Findings from the study –

• Baseline intragastric pH (1.3 +/- 0.1; mean +/- SD) showed a significant increase following the administration of the drug. The mean pH value for the entire period was 5.1 +/- 0.3 (p<0.00001).
• pH was found to increase following the administration of the combination treatment and values above pH 3 and pH 4 were attained promptly (median time: 27 sec and 54 sec, respectively).
• Initially, gastric pH was maintained above 4 for 23.0 +/- 5 minutes.
• In the post-drug period, the mean time lapsed with pH < 4 was 96 +/- 17 min, which was 32% of the total time.

Combined administration of antacid salts and low dose of ranitidine had an immediate and persistent effect. This combination could be effective and safe in sporadic heartburn or symptoms of mild gastroesophageal reflux.

References

1. Grimley CE, Constantinides S, Snell CC, et al. Inhibition of intragastric acidity in healthy subjects dosed with ranitidine 75 mg: a comparative study with cimetidine and placebo. Aliment Pharmacol Ther. 1997 Oct;11(5):875-9.
2. Améndola R, de los Santos MC, Massa JM, et al. Effects of a single low dose of ranitidine and effervescent antacids on intragastric acidity in healthy volunteers. Acta Gastroenterol Latinoam. 2007 Dec;37(4):231-7.