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

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.