Selective drug delivery to the colon using pectin-coated pellets

Area of Science:

• Pharmaceutics
• Drug Delivery Systems
• Polymer Science

Background:

• Colon-specific drug delivery aims to target therapeutic agents to the large intestine.
• Ethylcellulose is a common hydrophobic polymer used in drug coatings.
• Pectin is a natural polysaccharide with potential gelling and mucoadhesive properties.

Purpose of the Study:

• To evaluate the potential of ethylcellulose-pectin film coatings for colon-specific delivery of 5-aminosalicylic acid (5-ASA).
• To investigate the influence of ethylcellulose-pectin composition on drug release kinetics.
• To elucidate the drug release mechanism from coated pellets under simulated colonic conditions.

Main Methods:

• Preparation of ethylcellulose-pectin dispersions for film coating of 5-ASA pellet cores.
• In vitro drug release studies under simulated gastric, small intestinal, and colonic pH and time conditions.
• Inclusion of rat cecal contents to mimic colonic bacterial enzymatic activity.

Main Results:

• Negligible 5-ASA release observed in simulated gastric and small intestinal environments (first 5 hours).
• Significant drug release initiated in simulated colonic conditions (pH 6.8 with rat cecal contents).
• Drug release rate was dependent on the ethylcellulose-pectin ratio and composition, suggesting pectin's role in channel formation and enzymatic breakdown.

Conclusions:

• Pectin acts as a valuable additive to ethylcellulose films for achieving colon-specific drug release.
• The release mechanism involves osmotic pressure and pectin dissolution, leading to channel formation.
• Colonic bacterial enzymes play a crucial role in activating pectin breakdown and subsequent drug release.