Physicochemical properties of various alginate-based raft-forming antacid products: a comparative study


  • Hemali M. Savla Department of Pharmaceutics, IPA-MSB’s Bombay College of Pharmacy, Mumbai, Maharashtra, India
  • Isha V. Naik Department of Pharmaceutics, IPA-MSB’s Bombay College of Pharmacy, Mumbai, Maharashtra, India
  • Chandrashekhar Gargote Innovation and Development, Abbott Healthcare Pvt. Ltd., Mumbai, Maharashtra, India
  • Nischal Shashidhar Abbott India Ltd., Mumbai, Maharashtra, India
  • Sneha Nair Abbott India Ltd., Mumbai, Maharashtra, India
  • Mala D. Menon Department of Pharmaceutics, IPA-MSB’s Bombay College of Pharmacy, Mumbai, Maharashtra, India



Gastroesophageal reflux disease, Sodium alginate, Raft-forming formulations, Acid neutralization


Background: Alginate-based, raft-forming antacid products with reflux suppressant activity are complex formulations expected to achieve effective raft formation and cause elimination or displacement of the acid pocket, which is typically manifested in gastroesophageal reflux disease (GERD).

Methods: In the present study, six alginate-based raft-forming products commercially available in the Indian market were compared in terms of their acid neutralization properties, strength, resilience and structural and thermal properties of their rafts. Percent alginate content was also determined.

Results: Rafts of products containing calcium-based antacids formed voluminous, porous and floating rafts within seconds of addition to the simulated gastric fluid (SGF) compared with the products that contained aluminium and magnesium-based antacids. Marked differences were not evident in the ANC (acid neutralization capacity) values of the various products. No correlation was observed between ANC and raft-forming capacity or duration of neutralization. Raft structures affected their neutralization profiles. Rafts of porous and absorbent nature could retain their ANC probably due to release of trapped antacids. Further, raft strengths of only two products were above the British Pharmacopoeia specification of not less than 7.5 g. Sodium alginate content was within specifications (85-115%) for three of the six products.

Conclusions: Raft-forming formulations with higher alginate content and calcium-based antacids have better physicochemical properties such as ANC, neutralization profiles, raft strength and raft resilience than those with lower alginate content or those containing aluminium or magnesium-based antacids.

Author Biography

Mala D. Menon, Department of Pharmaceutics, IPA-MSB’s Bombay College of Pharmacy, Mumbai, Maharashtra, India

Adjunct Professor, Department of Pharmaceutics


Rohof WO, Bennink RJ, Smout AJ, Thomas E, Boeckxstaens GE. An alginate-antacid formulation localizes to the acid pocket to reduce acid reflux in patients with gastroesophageal reflux disease. J Clinic Gastroenterol Hepatol. 2013;11(12):1585-91.

Boeckxstaens G. The relationship between the acid pocket and GERD. Gastroenterol Hepatol. 2013;9(9):595.

Antunes C, Aleem A, Curtis SA. Gastroesophageal Reflux Disease. Treasure Island (FL): StatPearls Publishing; 2021.

Eusebi LH, Ratnakumaran R, Yuan Y, Solaymani-Dodaran M, Bazzoli F, Ford AC. Global prevalence of, and risk factors for, gastro-oesophageal reflux symptoms: a meta-analysis. Gut. 2018;67(3):430-40.

Bhatia SJ, Makharia GK, Abraham P, Bhat N, Kumar A, Reddy DN, et al. Indian consensus on gastroesophageal reflux disease in adults: a position statement of the Indian Society of Gastroenterology. Indian J Gastroenterol. 2019;38(5):411-40.

Dettmar PW, Gil-Gonzalez D, Fisher J, Flint L, Rainforth D, Moreno-Herrera A, et al. A comparative study on the raft chemical properties of various alginate antacid raft-forming products. Drug Develop Industr Pharma. 2018;44(1):30-9.

Lopes CM, Bettencourt C, Rossi A, Buttini F, Barata P. Overview on gastroretentive drug delivery systems for improving drug bioavailability. Int J Pharmaceut. 2016;510(1):144-58.

Prajapati VD, Jani GK, Khutliwala TA, Zala BS. Raft forming system-an upcoming approach of gastroretentive drug delivery system. J Controlled Release. 2013;168(2):151-65.

Ramdas T, Hosmani A, Somwanshi S. Raft technology for gastro retentive drug delivery. Int J Pharm Pharmaceut Res. 2015;3:232-52.

Daggy M, Brodie J, Jacoby H. Review article: alginate-raft formulations in the treatment of heartburn and acid reflux. Aliment Pharmacol Therapeut. 2000;14(6):669-90.

Yousaf M, Nirwan JS, Smith AM, Timmins P, Conway BR, Ghori MU. Raft-forming polysaccharides for the treatment of gastroesophageal reflux disease (GORD): systematic review. J Appl Polymer Sci. 2019;136(40):48012.

Enobakhare B, Bader D, Lee D. Concentration and M/G ratio influence the physiochemical and mechanical properties of alginate constructs for tissue engineering. J Appl Biomaterial Biomech. 2006;4(2):87-96.

Kapadia CJ, Mane VB. Raft-forming agents: antireflux formulations. Drug Development Industrial Pharm. 2007;33(12):1350-61.

Hampson F, Farndale A, Strugala V, Sykes J, Jolliffe I, Dettmar P. Alginate rafts and their characterisation. Int J Pharmaceut. 2005;294(1-2):137-47.

Washington N, Washington C, Wilson C, Davis S. The effect of inclusion of aluminium hydroxide in alginate-containing raft-forming antacids. Int J Pharmaceut. 1986;28(2-3):139-43.

Monograph-compound alginate antacid oral suspension, in British Pharmacopoeia. London, UK: The Stationary Office.

Darwish MK, El-Enin AS, Mohammed KH. Formulation, optimization, and evaluation of raft-forming formulations containing Nizatidine. Drug Development Industr Pharm. 2019;45(4):651-63.

Hampson FC, Jolliffe IG, Bakhtyari A, Taylor G, Sykes J, Johnstone LM, et al. Alginate–antacid combinations: raft formation and gastric retention studies. Drug Development Industr Pharm. 2010;36(5):614-23.

Poddar U. Diagnosis and management of gastroesophageal reflux disease (GERD): an Indian perspective. Indian Pediatrics. 2013;50(1):119-26.

Hanif M, Shah S, Rasul GA, Zaman M, Amjad MW, Raja MAG, et al. Enhancement of oral bioavailability of ibandronate through gastroretentive raft forming drug delivery system: in vitro and in vivo evaluation. Int J Nanomed. 2020;15:4847-58.

Gupta A, Garg S, Khar RK. Measurement of bioadhesive strength of mucoadhesive buccal tablets: design of an in-vitro assembly. Indian Drug Bombay. 1993;30:152.

Prajapati ST, Mehta AP, Modhia IP, Patel CN. Formulation and optimisation of raft-forming chewable tablets containing H2 antagonist. Int J Pharmaceut Investigat. 2012;2(4):176.

Hampson F, Banks A, Jolliffe I, Dettmar P. Raft resilience in alginate anti-reflux products. J Pharm Pharmacol. 2002;54:30-1.

Awad H, Aboul-Enein HY. A validated HPLC assay method for the determination of sodium alginate in pharmaceutical formulations. J Chromatogra Sci. 2013;51(3):208-14.

Skoog DA, Holler FJ, Crouch SR. Infrared absorption spectroscopy. principles of instrumental analysis. 7th ed. Cengage learning; 2017.

Strugala V, Dettmar PW, Thomas E. Evaluation of an innovative over-the-counter treatment for symptoms of reflux disease: quick-dissolving alginate granules. Int Scholar Res Notice. 2012;2012:1-7.

Washington N, Wilson C, Davis S. Evaluation of ‘raft-forming’antacid neutralizing capacity: in vitro and in vivo correlations. Int J Pharmaceut. 1985;27(2-3):279-86.

Wilkinson J, Abd-Elaziz K, denDaas I, Wemer J, vanHaastert M, Hodgkinson V, et al. Two placebo-controlled crossover studies in healthy subjects to evaluate gastric acid neutralization by an alginate–antacid formulation (Gaviscon double action). Drug Development Industr Pharm. 2019;45(3):430-8.




How to Cite

Savla, H. M., Naik, I. V., Gargote, C., Shashidhar, N., Nair, S., & Menon, M. D. (2021). Physicochemical properties of various alginate-based raft-forming antacid products: a comparative study. International Journal of Basic & Clinical Pharmacology, 10(12), 1330–1341.



Original Research Articles