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

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 2-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 minutes post-treatment. A confirmatory study of identical design was subsequently conducted (n = 20).

RESULTS: Monitoring pH using the multi-electrode 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. [Eudra CT 2014-003158-15; 2016-000539-42].