Two placebo-controlled crossover studies in healthy subjects to evaluate gastric acid neutralization by an alginate-antacid formulation (Gaviscon Double Action)

Drug Dev Ind Pharm. 2019 Mar;45(3):430-438. doi: 10.1080/03639045.2018.1546314. Epub 2018 Dec 2.


Objective: To investigate the intragastric acid neutralization activity of a combined alginate-antacid formulation.

Significance: Published studies have investigated the reflux-suppressing alginate component of Gaviscon Double Action (Gaviscon DA; RB, UK) but intragastric acid neutralization activity of the antacid component has not been evaluated in vivo.

Methods: Intragastric pH monitoring, using a custom-made 10-electrode catheter, was evaluated in a two-part exploratory study in healthy subjects; Part I (n = 6) tested suitability of the catheter using antacid tablets (Rennie; Bayer, Germany); Part II (n = 12) evaluated gastric acid neutralization activity of Gaviscon DA liquid (20 ml) versus placebo in fasted subjects using a randomized, open-label, crossover design. The primary endpoint was the percentage of time that intragastric pH ≥4 was measured during 30 min post-treatment. A confirmatory study of identical design was subsequently conducted (n = 20).

Results: Monitoring pH using the multielectrode catheter was a viable approach, directly detecting changes in intragastric pH following a single dose of antacid tablets. In the exploratory study, the percentage of time that pH ≥4 during 30 minutes post-treatment was 46.8% with Gaviscon DA liquid versus 4.7% with placebo (p = 0.0004). These findings were supported by the confirmatory study, where pH ≥4 was recorded 50.8% of the time with Gaviscon DA versus 3.5% with placebo (p = 0.0051). In this study, Gaviscon DA was safe and well tolerated.

Conclusions: These studies demonstrate the effective acid neutralizing capacity of Gaviscon DA versus placebo in healthy, fasted subjects. This adds to the evidence base for the combination of alginates and antacids.

Keywords: Alginate; antacid; crossover study; gastric acid; healthy volunteers.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Alginates / therapeutic use*
  • Aluminum Hydroxide / therapeutic use*
  • Antacids / therapeutic use*
  • Anti-Ulcer Agents / therapeutic use*
  • Calcium Carbonate / therapeutic use
  • Chemistry, Pharmaceutical / methods
  • Cross-Over Studies
  • Drug Combinations
  • Female
  • Gastric Acid / metabolism*
  • Gastroesophageal Reflux / drug therapy
  • Healthy Volunteers
  • Humans
  • Hydrogen-Ion Concentration
  • Magnesium / therapeutic use
  • Male
  • Silicic Acid / therapeutic use*
  • Sodium Bicarbonate / therapeutic use*
  • Tablets / therapeutic use
  • Young Adult


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