Alginic acid


Generic Name
Alginic acid
DrugBank Accession Number

Alginic acid, also referred to as algin or alginate, is a hydrophilic or anionic polysaccharide isolated from certain brown seaweed (Phacophycae) via alkaline extraction. It is present in cell walls of brown algae where it forms a viscous gel when binding with water. Alginic acid is a linear polymer consisted of L-glucuronic acid and D-mannuronic acid residues connected via 1,4-glycosidic linkages 4. Available in different types of salt, alginic acid has been used in a variety of uses in food, cosmetics and pharmaceu-tical products for over 100 years 4. Alginic acid is an FDA-approved food ingredient in soup and soup mixes as an emulsifier, thickener, and stabilizer 5. It is also available in oral dietary supplements and is found in antacids such as Gaviscon to inhibit gastroesophageal reflux by creating a physical barrier in presence of gastric acid 9. Alginate-based raft-forming formulations in the management of heartburn and gastric acid reflux have been used worldwide for over 30 years 4.

Small Molecule
Approved, Investigational
  • (Alginate)n
  • (Alginate)n+1
  • algin
  • alginate
  • Alginic acid
  • Norgine
External IDs
  • A 2830-9
  • E-400
  • INS NO.400
  • INS-400



Indicated for the management of gastric reflux, reflux oesophagitis, hiatus hernia, heartburn (including heartburn of pregnancy) and similar gastric distress 9.

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Associated Conditions
Indication TypeIndicationCombined Product DetailsApproval LevelAge GroupPatient CharacteristicsDose Form
Used in combination to treatAcid refluxCombination Product in combination with: Calcium carbonate (DB06724), Aluminum hydroxide (DB06723)••• •••••••••••••
Used in combination for symptomatic treatment ofAcid refluxCombination Product in combination with: Simethicone (DB09512)••••••••••••••••••••••
Used in combination to treatDyspepsiaCombination Product in combination with: Calcium carbonate (DB06724), Aluminum hydroxide (DB06723)••• •••••••••••••
Used in combination for symptomatic treatment ofDyspepsiaCombination Product in combination with: Potassium bicarbonate (DB11098)••••••••••••••••••• ••••••••
Used in combination for symptomatic treatment ofFlatulenceCombination Product in combination with: Simethicone (DB09512)••••••••••••••••••••••
Contraindications & Blackbox Warnings
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Alginic acid reduces reflux via its floating, foaming, and viscous properties 2. Alginic acid precipitates upon contact with gastric acid to create a mechanical barrier, or a "raft", that displaces the postprandial acid pocket 3. The formation of a raft is thought to occur rapidly, often within a few seconds of dosing 4. In clinical trials, alginic acid was effective in reducing the symptoms of gastroesophageal reflux disease (GERD) 3. In healthy volunteers, alginic acid in combination with an antacid was effective in decreasing postprandial reflux in the upright position 1. Alginic acid is able to bind to cations when ingested 6.

Mechanism of action

Once orally administered, alginic acid reacts with gastric acid to form a floating "raft" of alginic acid gel on the gastric acid pool. Alginate-based raft-forming formulations commonly contain sodium or bicarbonate; bicarbonate ions are converted to carbon dioxide in presence of gastric acid and get entrapped within the gel precipitate, converting it into a foam which floats on the surface of the gastric contents, much like a raft on water 4. The "raft" has a near neutral pH due to carbon dioxide and floats on the stomach contents and potentially functions as a barrier to impede gastroesophageal reflux 1,9. In severe cases, the raft itself may be refluxed into the oesophagus in preference to the stomach contents and exert a demulcent effect 9.


The absorption into the systemic circulation from oral formulations of alginic acid is reported to be minimal, as the mode of action of alginic acid is physical 9.

Volume of distribution

This pharmacokinetic parameter is unlikely to apply for alginic acid.

Protein binding

This pharmacokinetic parameter is unlikely to apply for alginic acid.


This pharmacokinetic parameter is unlikely to apply for alginic acid.

Route of elimination

This pharmacokinetic parameter is unlikely to apply for alginic acid.


This pharmacokinetic parameter is unlikely to apply for alginic acid.


This pharmacokinetic parameter is unlikely to apply for alginic acid.

Adverse Effects
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Probable oral lethal dose reported in humans is above 15 g/kg 6. Ingestion of large quantities may result in abdominal distension, intestinal obstruction, nausea, vomiting, and difficulty swallowing. Aspiration or inhalation may lead to pneumonitis 6. In the event of overdosage symptomatic treatment should be given 9.

Not Available
Pharmacogenomic Effects/ADRs
Not Available


Drug Interactions
This information should not be interpreted without the help of a healthcare provider. If you believe you are experiencing an interaction, contact a healthcare provider immediately. The absence of an interaction does not necessarily mean no interactions exist.
Not Available
Food Interactions
No interactions found.


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Product Ingredients
IngredientUNIICASInChI Key
Sodium alginateC269C4G2ZQ9005-38-3Not applicable
Mixture Products
NameIngredientsDosageRouteLabellerMarketing StartMarketing EndRegionImage
ACIFREE® DOBLE ACCIÓNSodium alginate (5 g) + Calcium carbonate (3.25 g) + Sodium bicarbonate (2.13 g)SuspensionOralLABORATORIOS DEMAC LTDA.2019-12-03Not applicableColombia flag
AGRILAX SUSPENSIONSodium alginate (2.5 g) + Sodium bicarbonate (2.67 g)SuspensionOralCOLOMPACK S.A.2012-09-03Not applicableColombia flag
AGRILAX SUSPENSIONSodium alginate (2.5 g) + Sodium bicarbonate (2.67 g)SuspensionOralCOLOMPACK S.A.2012-09-03Not applicableColombia flag
ALGIDROX PLUS SUSPENSION ORALSodium alginate (2.5 g) + Sodium bicarbonate (2.67 g)SuspensionOralCOASPHARMA S.A.S.2018-05-18Not applicableColombia flag
ARGİCON DOUBLE ACTİON 250 MG/106,5 MG/187,5 MG ÇIĞNEME TABLETI , 48 TABLETSodium alginate (250 mg) + Calcium carbonate (187.5 mg) + Sodium bicarbonate (106.5 mg)Tablet, chewableOralALİ RAİF İLAÇ SAN. A.Ş.2016-10-31Not applicableTurkey flag


ATC Codes
A02BX13 — Alginic acid
Drug Categories
Not classified
Affected organisms
Not Available

Chemical Identifiers

CAS number


General References
  1. Castell DO, Dalton CB, Becker D, Sinclair J, Castell JA: Alginic acid decreases postprandial upright gastroesophageal reflux. Comparison with equal-strength antacid. Dig Dis Sci. 1992 Apr;37(4):589-93. [Article]
  2. Malmud LS, Charkes ND, Littlefield J, Reilley J, Stern H, Rosenberg R, Fisher RS: The mode of action alginic acid compound in the reduction of gastroesophageal reflux. J Nucl Med. 1979 Oct;20(10):1023-8. [Article]
  3. Leiman DA, Riff BP, Morgan S, Metz DC, Falk GW, French B, Umscheid CA, Lewis JD: Alginate therapy is effective treatment for gastroesophageal reflux disease symptoms: a systematic review and meta-analysis. Dis Esophagus. 2017 Feb 1;30(2):1-8. doi: 10.1111/dote.12535. [Article]
  4. Mandel KG, Daggy BP, Brodie DA, Jacoby HI: Review article: alginate-raft formulations in the treatment of heartburn and acid reflux. Aliment Pharmacol Ther. 2000 Jun;14(6):669-90. [Article]
  5. FDA CFR - Code of Federal Regulations Title 21 Sec. 184.1011 Alginic acid [Link]
  6. ALGINIC ACID - National Library of Medicine HSDB Database - Toxnet [Link]
  7. TITCK Product Information: Gaviscon Double Action (sodium alginate/sodium bicarbonate/calcium carbonate) chewable tablets [Link]
  8. INVIMA Product Authorization: Gastrofast Advance (sodium alginate/magaldrate/simeticone/sodium bicarbonate) for oral use [Link]
  9. Gaviscon Summary of Product Characteristics [File]
Human Metabolome Database
KEGG Compound
PubChem Compound
PubChem Substance

Clinical Trials

Clinical Trials
4CompletedBasic ScienceHealthy Volunteers (HV)1
4CompletedPreventionGastrointestinal Symptoms1
4CompletedTreatmentBowel Preparation for Colonoscopy1
4CompletedTreatmentHeartburn in Pregnancy1


Not Available
Not Available
Dosage Forms
Tablet, chewableOral
Tablet, chewableOral500 MG
SuspensionOral200 mg/10ml
SuspensionOral325 MG/10ML
Tablet, chewableOral187.5 MG
SuspensionOral160 MG/10ML
Tablet, chewableOral80 MG
Tablet, chewableBuccal
SuspensionOral2.5 g
GelTopical3 g
SuspensionOral2.94 g
Not Available
Not Available


Not Available
Experimental Properties
Not Available
Predicted Properties
Not Available
Predicted ADMET Features
Not Available


Mass Spec (NIST)
Not Available
Not Available
Chromatographic Properties
Collision Cross Sections (CCS)
Not Available

Drug created at June 23, 2017 20:43 / Updated at May 29, 2021 18:11