Carboxymethyl Starch Films as Enteric Coatings: Processing and Mechanistic Insights

Area of Science:

• Materials Science
• Pharmaceutical Technology
• Polymer Chemistry

Background:

• Developing effective gastro-protective tablet coatings is crucial for targeted drug delivery and protecting sensitive active pharmaceutical ingredients (APIs).
• Traditional coatings may face challenges in achieving optimal gastro-resistance and controlled release profiles.
• Starch derivatives offer a potential avenue for developing biodegradable and biocompatible coating materials.

Purpose of the Study:

• To investigate the application of carboxymethyl starch (CMS) derivatives as novel gastro-protective tablet coatings.
• To evaluate the influence of plasticizers on the structural, mechanical, and water absorption properties of CMS films.
• To assess the gastro-resistance and intestinal disintegration of tablets coated with optimized CMHAS formulations.

Main Methods:

• Synthesis of carboxymethyl high amylose starch (CMHAS) via carboxymethylation of high amylose starch (HAS).
• Film preparation using aqueous casting of CMS solutions with glycerol or sorbitol as plasticizers.
• Characterization of film structure and properties using FTIR, TGA, XRD, and mechanical testing.
• Evaluation of coating performance in simulated gastric and intestinal fluids using an industrial pan coater.

Main Results:

• CMHAS films exhibited suitable structural and mechanical properties for tablet coatings.
• Plasticizers (sorbitol, glycerol) influenced film organization, drying rate, and water vapor absorption.
• Tablets coated with CMHAS demonstrated effective gastro-resistance (up to 2 hours) in simulated gastric fluid.
• Coated tablets successfully disintegrated in simulated intestinal fluid (SIF), indicating controlled release potential.

Conclusions:

• Carboxymethyl high amylose starch (CMHAS) derivatives are highly effective as gastro-protective tablet coatings.
• The inclusion of plasticizers like sorbitol or glycerol optimizes the performance of CMHAS coatings.
• CMHAS presents significant potential for use in pharmaceutical and nutraceutical solid dosage forms requiring gastro-protection.