Application of Eudragit Controlled-Release Polymers in Colon-Targeted Drug Delivery Systems

Colon-targeted drug delivery systems (CTDDS) are increasingly important for treating intestinal diseases like ulcerative colitis, Crohn’s disease, and colorectal cancer, as well as enhancing systemic absorption of drugs degraded in the upper GI tract. Eudragit polymers, a family of methacrylate-based copolymers, are widely used in CTDDS due to their customizable pH-dependent, time-controlled, and enzyme-triggered release properties.

Overview of Eudragit Polymers

Eudragit, developed by Evonik, includes various polymethacrylates with excellent film-forming ability, biocompatibility, and tailored solubility:

• Eudragit L & S: Dissolve at pH > 5.5 (L) and > 7.0 (S), ideal for enteric coatings.

• Eudragit FS 30 D: Dissolves at pH > 7.0, specifically designed for colon targeting.

• Eudragit RS/RL: Water-insoluble, pH-independent, used for sustained release.

• Eudragit NE: Neutral and non-ionic, suitable for moisture protection and taste masking.

Colon-Targeted Delivery Mechanisms

1. pH-Dependent Release:
   Eudragit S and FS 30 D dissolve only at colon pH (~7.0+), ensuring site-specific drug release, protecting drugs from stomach acid, and reducing GI side effects.

2. Time-Controlled Release:
   Using Eudragit RS/RL, formulations delay drug release by 5–6 hours to target the colon after oral administration.

3. Combination Systems:
   Combining Eudragit polymers with biodegradable polysaccharides (e.g., pectin) leverages colonic bacteria to trigger precise drug release.

Case Example: Mesalazine (5-ASA)

Mesalazine coated with Eudragit S100 targets the colon to treat ulcerative colitis effectively, minimizing upper GI side effects and enhancing local anti-inflammatory effects.

Advantages of Eudragit in CTDDS

• Customizable pH-triggered solubility

• Sustained-release options with low permeability variants

• Strong film-forming and mechanical properties

• Compatibility with various excipients and drugs

• Scalable coating processes (spray, fluid bed)

Challenges and Considerations

• GI pH variability can influence release profiles

• Coating integrity must withstand gastric conditions

• Polymer blends need optimization for balance between release and stability

• Regulatory compliance with pharmacopeial standards is essential

Conclusion

Eudragit polymers are vital for precise, reliable colon-targeted drug delivery, enabling tailored release profiles for GI and systemic treatments. As interest in microbiota-targeted and advanced therapies grows, Eudragit-based formulations will continue to drive pharmaceutical innovation.