RESUMO
AIM: To compare the effect of effervescent ranitidine, almagate (magnesium carbonate-aluminium hydroxide) and placebo on gastric pH, in fasting and postprandial conditions. METHODS: Twelve healthy volunteers underwent a gastro-oesophageal pH monitoring on three different occasions after the administration of each of the following randomly allocated treatments: almagate, effervescent ranitidine and placebo. Treatment effects were assessed in fasting and postprandial conditions. Onset and duration of alkalinization, percentage of time with pH > 4 and median gastric pH after treatments were calculated in both periods. RESULTS: Onset of action of effervescent ranitidine was similar to almagate in fasting [median 1.2 min (IQR: 0.6-12.7) vs. 2.9 min (0.4-227.6)] and postprandial conditions [1.4 min (0.5-4.9) vs. 4.1 min (1.3-63.8)] and both were significantly faster than placebo [fasting 211.1 min (2.7-240); postprandial 240 min (175.6-240)]. The duration of action of effervescent ranitidine was statistically significant longer than almagate in fasting [235 min (105.2-239.4) vs. 19.4 min (6.7-38.8)] and postprandial conditions [171.8 min (133.2-239.5) vs. 61.3 min (44.7-91.9)]. Effervescent ranitidine was more effective than almagate in increasing the percentage of time with a pH > 4 both in fasting (73.9% vs. 7.3%) and postprandial (59.1% vs. 21.3%). CONCLUSIONS: Effervescent ranitidine shows an effect on gastric pH as fast as almagate but provides a duration of alkalinization longer than almagate, in both fasting and postprandial conditions.