Binders for colon specific drug delivery: an in vitro evaluation

Area of Science:

• Pharmaceutical Sciences
• Drug Delivery Systems
• Polymer Science

Background:

• Targeted drug delivery to the colon is crucial for treating colonic diseases and improving therapeutic efficacy.
• Conventional oral formulations often result in premature drug release in the upper gastrointestinal tract, limiting their effectiveness for colon-specific conditions.

Purpose of the Study:

• To develop and evaluate single-unit, site-specific drug formulations for targeted colon drug release.
• To investigate the potential of various polysaccharides and synthetic polymers as binders in colon-specific drug delivery systems.

Main Methods:

• Tablets containing indomethacin were prepared using xanthan gum, guar gum, chitosan, or Eudragit E as binders.
• Tablets were enteric-coated with Eudragit-L 100 for protection in the stomach.
• In-vitro drug release studies were conducted in simulated gastric (pH 1.2) and intestinal (pH 6.8) environments.

Main Results:

• Chitosan (3%) as a binder showed minimal drug release (12.5%) within 5 hours, indicating effective colon targeting.
• Guar gum failed to protect drug release under similar conditions.
• Xanthan gum formulations exhibited time-dependent release (28% in 5 hours), while Eudragit E (8.88%) showed promise for water-insoluble drugs, particularly in Inflammatory Bowel Disease (IBD).

Conclusions:

• Chitosan is a preferred binder over guar gum for colon targeting of water-insoluble drugs.
• Formulations with chitosan and Eudragit E offer high site specificity due to retarded drug release until colonic conditions trigger degradation or solubilization.