Gaviscon Double Action Liquid (antacid & alginate) is more effective than antacid in controlling post-prandial oesophageal acid exposure in GERD patients: a double-blind crossover study

Aliment Pharmacol Ther. 2014 Sep;40(5):531-7. doi: 10.1111/apt.12857. Epub 2014 Jul 10.


Background: Recent studies have shown that Gaviscon Double Action Liquid (a combination alginate-antacid) administered post-prandially co-localises with the acid pocket, the 'reservoir' for post-prandial acid reflux.

Aim: To compare the effectiveness of Gaviscon Double Action Liquid to an equivalent strength antacid without alginate in controlling post-prandial acid reflux in GERD patients.

Methods: Fourteen GERD patients undertook two 3.5-h high-resolution manometry/pH-impedance studies during which they ate a standardised meal. In a double-blinded randomised crossover design they then took Gaviscon or CVS brand antacid, each with ~18 mmol/L acid neutralising capacity. The primary outcome was distal oesophageal acid exposure; secondary outcomes were number of reflux events, proximal extent of reflux, nadir pH of the refluxate, mechanism of reflux and reflux symptoms scored with a validated instrument.

Results: Ten patients completed the study. Gaviscon studies had significantly less distal oesophageal acid exposure and greater nadir refluxate pH in the 30-150 min post-prandial period than antacid studies. There were no differences in the number of reflux events (acid or weakly acidic) or the number of proximal reflux events (15-17 cm above the LES) with either study medication.

Conclusions: Gaviscon Double Action Liquid is more effective than an antacid without alginate in controlling post-prandial oesophageal acid exposure. However, the number and spatial distribution of reflux events within the oesophagus are similar. This suggests that Gaviscon main effectiveness relates to its co-localisation with and displacement/neutralisation of the post-prandial acid pocket, rather than preventing reflux.

Publication types

  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Alginates / therapeutic use*
  • Aluminum Hydroxide / therapeutic use*
  • Antacids / therapeutic use*
  • Calcium Carbonate / therapeutic use*
  • Cross-Over Studies
  • Double-Blind Method
  • Drug Combinations
  • Electric Impedance
  • Esophagus / drug effects
  • Female
  • Gastric Acid / metabolism
  • Gastroesophageal Reflux / drug therapy*
  • Humans
  • Hydrogen-Ion Concentration
  • Magnesium Hydroxide / therapeutic use*
  • Male
  • Manometry
  • Middle Aged
  • Postprandial Period
  • Silicic Acid / therapeutic use*
  • Sodium Bicarbonate / therapeutic use*


  • Alginates
  • Antacids
  • Drug Combinations
  • Silicic Acid
  • Aluminum Hydroxide
  • alginate, aluminium hydroxide, magnesium trisilicate, sodium bicarbonate drug combination
  • Sodium Bicarbonate
  • Calcium Carbonate
  • Magnesium Hydroxide