In Vitro and In Vivo Studies of a Verapamil-Containing Gastroretentive Solid Foam Capsule

Gastroretentive systems may overcome problems associated with incomplete drug absorption by localized release of the API in the stomach. Low-density drug delivery systems can float in the gastric content and improve the bioavailability of small molecules. The current publication presents verapamil-HCl-containing solid foam prepared by continuous manufacturing. Production runs were validated, and the foam structure was characterized by micro-CT scans and SEM. Dissolution properties, texture changes during dissolution, and floating forces were analyzed. An optimized formulation was chosen and given orally to Beagle dogs to determine the pharmacokinetic parameters of the solid foam capsules. As a result, a 12.5 m/m% stearic acid content was found to be the most effective to reduce the apparent density of capsules. Drug release can be described by the first-order model, where 70% of verapamil dissolved after 10 h from the optimized formulation. The texture analysis proved that the structures of the solid foams are resistant. Additionally, the floating forces of the samples remained constant during their dissolution in acidic media. An in vivo study confirmed the prolonged release of the API, and gastroscopic images verified the retention of the capsule in the stomach.