A novel pH- and time-based multi-unit potential colonic drug delivery system. I. Development

Area of Science:

• Pharmaceutical Sciences
• Drug Delivery Systems
• Polymer Chemistry

Background:

• Targeted drug delivery to the colon remains a challenge.
• Polymethacrylates offer tunable pH-dependent dissolution properties for controlled release.
• 5-aminosalicylic acid (5-ASA) is a key therapeutic agent for inflammatory bowel disease.

Purpose of the Study:

• To develop and evaluate a novel pH-triggered drug delivery system for colon-specific delivery of 5-ASA.
• To utilize polymethacrylates with specific dissolution profiles for precise drug release.
• To assess the release kinetics of 5-ASA from the developed system under simulated physiological conditions.

Main Methods:

• Pellets of 5-ASA were prepared by powder layering on nonpareils.
• Pellets were coated with a combination of pH-independent (Eudragit RL/RS) and pH-dependent (Eudragit FS) polymers.
• Drug release was evaluated in phosphate buffers at various pH values after simulated gastric pre-soaking.
• Scanning electron microscopy (SEM) was used to assess coating uniformity.

Main Results:

• Coated pellets exhibited uniform polymer layers as confirmed by SEM.
• No 5-ASA release was observed for 12 hours at pH 6.5.
• Sustained drug release occurred over 12 hours at pH 7.0 and 7.5, with faster release at pH 7.5.
• A lag time was observed at pH 7.0 but not at pH 7.5.

Conclusions:

• The developed polymethacrylate-based system effectively targets the colon by preventing premature drug release.
• The combination of Eudragit RL/RS and Eudragit FS polymers ensures pH-triggered release in the distal intestine.
• This novel delivery system shows significant potential for effective colon-specific delivery of 5-ASA.