Novel formulation of uncoated enteric capsule shells: Study the effect of gelling agents and salts on the rheology and physical properties

Abstract

Currently, pharmaceutical technology offers new choices for protecting acid-sensitive substances from the stomach environment by dosage form of an enteric coating or the encapsulation of drugs in enteric capsules. Coating gelatin capsules is challenging, cost-intensive, and energy-consuming, as the smoothness of their surface hinders the adhesion of the film. In this study, the formulation of an uncoated gelatin-based enteric capsule shell composite is developed. The effect of four different gelling agents and six salts on the preparation of capsules is investigated. Potassium acetate (KAC) and κ-carrageenan are examined and selected as the best salt and gelling agent, respectively. The physicochemical, surface, and cross-section morphology, mechanical, and drug release properties of prepared enteric capsules (without (F1) and with (F2) gelatin) were characterized. The drug release of optimized capsules (F1, F2) was tested using pantoprazole. The results showed high stability (120 min) of prepared capsules in the stomach environment with no release (pH = 1.2), and then started to release in the intestinal medium (pH = 6.8) after 16 min, which is great according to the definition of the enteric capsule. Furthermore, the tensile strength of gelatin-based enteric capsules and pure gelatin capsules was tested and compared.