Development of Enteric Coated Hard Gelatin Capsules for Oral Peptide Delivery

Oral administration of macromolecules such as insulin is a very attractive and patient compliant method of drug delivery. However, most of these macromolecules have to be administered via injection due to their very poor oral bioavailability, which can be attributed to (i) degradation in the gastrointestinal tract, and (ii) negligible permeability across intestinal epithelium. These challenges in oral delivery of macromolecules can be addressed by engineering a carrier capable of delivering therapeutic doses of these macromolecular drugs. One such carrier is an enteric coated hard gelatin capsule. Enteric coated gelatin capsules, while maintaining their integrity in acidic environment of stomach, degrade rapidly in neutral/basic pH of small intestine to release their contents; and thus avoid enzymatic degradation during gastric transit of the dosage form. In this project, enteric coated gelatin capsules were prepared by coating hard gelatin capsules with different concentrations of Eudragit L100, a FDA approved enteric coating polymer. Enteric coated capsules were tested for their ability to endure highly acidic (pH 2.5) medium at 37⁰C for one hour (approximate time for stomach transit), and for degradation in neutral pH (6.5-7.0) thereafter. Enteric coating allowed the capsules to survive acidic environment up to an hour, and started dissolving once placed in neutral solution. Further studies need to be done to optimize the delivery system, so as to safely deliver their contents to the small intestine. Enteric coated gelatin capsules can be a patient compliant and non-invasive approach for oral delivery of peptides, otherwise being administered via injections.