• Barbosa, J. & Conway, B. & Merchant, H., (2017) “Going Natural: Using polymers from nature for gastroresistant applications”, British Journal of Pharmacy 2(1). DOI: https://doi.org/10.5920/bjpharm.2017.01 

Quote: “This article provides a critical review of natural substances employed in producing gastroresistant products, their shortcomings, and potential industrial applications.”

From conclusions: “Recently several natural materials like pectin/alginate, shellac and alginate have been employed. However, their gastroresistant properties are not comparable to those employed in pharmaceutical products and lack robustness over a wider spectrum of gastric pH.”

• Czarnocka JK, Alhnan MA. “Gastro-resistant characteristics of GRAS-grade enteric coatings for pharmaceutical and nutraceutical products.” Int J Pharm. 2015;486(1-2):167-74. Epub 2015 Mar 18. PMID: 25796126
DOI: https://doi.org/10.1016/j.ijpharm.2015.03.039

Quote: “The use of naturally derived excipients to develop enteric coatings offers significant advantages ove conventional synthetic polymers. values.”

Quote: “In conclusion, none of the GRAS-grade coatings fully complied with the different biological demands of delayed release coating systems.”

• Al-Gousous J, Tsume Y, Fu M, Salem II, Langguth P. “Unpredictable Performance of pH-Dependent Coatings Accentuates the Need for Improved Predictive in Vitro Test Systems.” Mol Pharm. 2017 Dec 4;14(12):4209-4219. Epub 2017 Feb 28. PMID: 28199791.
DOI: https://doi.org/10.1021/acs.molpharmaceut.6b00877

Quote: “The currently available enteric-coatings are based on pH-sensitive weakly acidic polymers. Despite the long history of their use, the causes behind their performance often being unpredictable have not been properly investigated with most of the attention being focused only on the gastric emptying. However, little attention has been given to the postgastric emptying disintegration and dissolution of these dosage forms. This lack of attention has contributed to the difficulty in predicting the in vivo behavior of these dosage forms and to cases of bioavailability problems with some enteric-coated products. Therefore, increased attention needs to be given to this issue.”

• Y. Farag and C. S. Leopold. “Physicochemical Properties of Various Shellac Types.” Dissolution Technologies. MAY 2009.
DOI: https://doi.org//10.14227/DT160209P33

Quote: “Shellac consists of polyesters of mainly aleuritic acid, shellolic acid, and a small amount of free aliphatic acids (1, 2). The composition varies depending on the insect species as well as the host tree from which the raw material is obtained.”

• Qureshi SA, Caillé G, Lacasse Y, McGilveray IJ. “Pharmacokinetics of two enteric-coated ketoprofen products in humans with or without coadministration of omeprazole and comparison with dissolution findings.” Pharm Res. 1994 Nov;11(11):1669-72. PMID: 7870688.
DOI: https://doi.org/10.1023/a:1018934526499

Quote: “Elevated gastric pH diminishes the in vivo dissolution of weakly basic drugs. A change of gastric pH to a higher value or the intestinal pH to a lower value may result in untimely drug release form enteric coated formulations with possible drug degradation in the stomach or obstruction of drug release in the small intestine.”