A study was conducted by Orenstein and colleagues to look into the pharmacokinetics and pharmacodynamics of a single dose of ranitidine 75mg in children with symptoms of gastro-esophageal reflux disease (GERD).

Children 4 to 11 years of age, having symptoms of heartburn suspected to be because of GERD, were enrolled at six centers. A total of 29 children were assessed. Nineteen of them were given a single dose of oral ranitidine 75mg while 10 received a placebo. Children were subjected to intragastric pH monitoring and serial blood sampling for 6h following a single dose of ranitidine or placebo.

• With ranitidine 75mg, the median Cmax value of 477ng/mL was noted within a median of 2.5h after dosing. The median half-life was 2 h.
• The intragastric pH started rising about 30min after dosing with ranitidine to a peak of pH ˜ 4.
• The pH in the ranitidine group was persistently higher compared to the placebo group through the entire 6h period.
• Adverse events were generally mild.

Ranitidine 75mg was found to significantly increase intragastric pH in children and the pharmacokinetic and pharmacodynamic profiles appeared to be similar to those observed in adults.

The drug can be effective for controlling intragastric acidity for 5-6 h in children 4-11 years of age.

Source: Orenstein SR, Blumer JL, Faessel HM, et al. Ranitidine, 75 mg, over-the-counter dose: pharmacokinetic and pharmacodynamic effects in children with symptoms of gastro-oesophageal reflux. Aliment Pharmacol Ther. 2002;16(5):899-907.