Heartburn and acid reflux are widespread in the general population. In a Norwegian population-based study, approximately 40% of the test subjects reported suffering from reflux symptoms at least once a week . If we transfer these results to the German population, it would mean there were around 33 million people suffering from reflux symptoms . The antacid Rennie® has proved to be a rapid, effective, and safe tool in the symptomatic therapy of acid-related symptoms such as heartburn, acid reflux and a feeling of fullness. The calcium carbonate (680 mg) and magnesium carbonate (80 mg) it contains react with the stomach acid to form water and soluble mineral salts . Through this reaction, the proton concentration is lowered. Although Rennie has been on the market for decades now, there are so far not many published studies investigating the onset of the neutralising action.
Onset of the neutralising action of antacids based on calcium and magnesium carbonate using an artificial stomach model
An in-vitro study
Reflux symptoms: a common ailment
Investigating the neutralising effect
For testing purposes, the SHIME® apparatus (Simulator of the Human Intestinal Microbial Ecosystem, ProDiegest, Belgium) was used. This device models the individual compartments of the intestine, subdivided into stomach, duodenum, and colon. SHIME has been used extensively in the last 25 years and validated using in-vivo parameters. It constitutes an accepted scientific approximation of the human gastrointestinal tract. The artificial stomach contained 100 ml 0.1 N HCl and other important components such as mucins, salts (KCl, NaCl) and the reference protein bovine serum albumin (BSA).
Results of the in-vitro study
For the antacid Rennie® it was shown that the pH (pH 1.0) increased to > 3 within 40 s (± 2 s) and was maintained for 56 min 1 s (± 1 min 9 s). After 1 min 54 s (± 12 s), a pH of 4.5 was reached (Fig. 1A) and the maximum pH of 5.24 was attained within 10 min. This maximum pH was maintained for 9 min 56 s (± 44 s). Between 30 min and 1 h, the pH began to drop again (Fig. 1B). By contrast, the placebo only demonstrated a maximum increase to pH 1.28.
Fig. 1. Average pH profile of six independent repetitions of the incubation after addition of the calcium/magnesium carbonate-based antacid or placebo to the stomach medium. A. First 5 minutes of the incubation. B. Changes during the entire incubation time (2 h). Throughout the entire incubation, 0.1 N HCl was added at 3 ml/min, whilst the stomach emptying was simulated by removing the content at a rate of 1.5 ml/min.
- DGVS Weißbuch Gastroenterologie 2020/2021, Gastroösophagale Refluxkrankheit, Herbert Koop.
- https://www.pharmazeutische-zeitung.de/ausgabe-182010/rennie-verwender-bestaetigen-zuverlaessige-wirkung-bei-sodbrennen/ (Accessed 07.11.2022)
- Voropaiev M, Nock D. Onset of acid-neutralizing action of a calcium/magnesium carbonate-based antacid using an artificial stomach model: an in vitro evaluation. BMC Gastroenterol. 2021 Mar 6;21(1):112. doi: 10.1186/s12876-021-01687-8. PMID: 33676393; PMCID: PMC7937289.
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Conflicts of interest: S. Bartylla and M. Grieswelle are employees of Steigerwald Arzneimittelwerk GmbH, Darmstadt.
Disclosure: Publication financed by Steigerwald Arzneimittelwerk GmbH, Darmstadt.