A single-center, randomized, open cross-over study recruited 24 healthy males aged 19 to 32 years. Investigators assessed intragastric pH values measured over 6 h after the administration of one dose of ranitidine and compared the results with those after administration of aluminium oxide-magnesium hydroxide (Al-Mg-hydroxide) and placebo. A total of 19 study participants were available for all three measurements.

After an overnight fast, intragastric pH was measured for 7 hours and the percentage time during which the pH was >3.5 and the area under the curve of the obtained pH-curves were compared.

• Researchers noted a highly statistically significant difference between ranitidine and Al-Mg-hydroxide and placebo. There appeared to be no such difference between Al-Mg-hydroxide and placebo.
• The onset of action of ranitidine was almost immediate.

The researchers thus concluded that ranitidine was superior in healthy volunteers.

Source: Propst A, Propst T, Judmaier G. Comparison of the effects of ranitidine effervescent tablets and magnesium hydroxide-aluminium oxide on intragastric acidity. A single-centre, randomised, open cross-over study. Arzneimittelforschung. 1996 Jun;46(6):621-4.