Two placebo-controlled crossover studies in healthy subjects to evaluate gastric acid neutralization by an...

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

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.

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).

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.

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.