As a treatment for reflux disease, proton pump inhibitors (PPIs) are seen as the mainstay of medical therapy but alginate-based formulations are an effective option for the immediate relief of symptoms.

What are alginates?
An alginate is derived from seaweed. Alginate-based formulations either contain alginate as the principle active agent or combine the alginate with antacid (a type of medicine that is alkaline in nature and works by neutralising excess acid).

How do they work?
Alginate-based products provide a physical barrier and work by forming a neutral floating gel or raft (a protective barrier) on top of the stomach to prevent stomach contents, including pepsin and bile acids, from backing up into the oesophagus and airways.

What are antacids?
Antacids are drugs intended to provide immediate, short term relief for symptoms by neutralising the hydrochloric acid your stomach uses to aid digestion. Most antacids will contain one of these key ingredients: Calcium Carbonate, Magnesium Hydroxide, Aluminum Hydroxide and/or Sodium Bicarbonate.

Alginate-based products are complex formulations as they require three chemical reactions to take place simultaneously.

  • Alginate transforming to alginic acid
  • Sodium carbonate reacting to form carbon dioxide
  • Calcium carbonate releasing free calcium ions to bind with alginic acid and provide strength to the raft

What’s the latest research?
Professor Peter Dettmar, who developed Peptest, is the former global R&D Director of Gastrointestinals for Reckitt Benckiser Healthcare and was involved in developing Gaviscon and Gaviscon Advance.

As a world expert in alginates, he recently took part in a comparative study on the raft chemical properties of various alginate antacid raft-forming products – conducted by Reckitt Benckiser Healthcare and published in Drug Development and Industrial Pharmacy – and he has shared the results here.

What brands were tested in the study?
A range of alginate products were chosen from across Europe and global markets. All products selected are claimed as proficient raft formers by their manufacturers. The main active ingredient across the products evaluated was sodium alginate. The products were:

  • Gaviscon Double Action
  • Gaviscon Original
  • Peptac
  • Algycon
  • Maalox RefluRAPID
  • Rennie Duo

What did the comparison study find?
Small differences in the way products are formulated can have a significant effect on the way the three chemical reactions described earlier take place.

The results generated from this work show that Gaviscon Double Action liquid offers a superior in vitro performance than the other products tested in terms of drug utilisation and acid neutralisation capacity.

Gaviscon Double Action was found to be superior in the chemical properties of the raft that are relevant to the efficacy of the product, by trapping a superior amount of alginate within the raft, allowing for antacid to be trapped within the raft and consequently providing a longer duration of neutralisation.

Rennie Duo demonstrated the highest acid neutralisation capacity due to the presence of high antacid content, however this was to the detriment of the product’s ability to form a raft – it was too porous allowing acid to filter through and spend insufficient time within the raft to react with the antacid present.

Download the full alginate medication comparison study here…