Novel gastroretentive controlled-release drug delivery system for amoxicillin therapy in veterinary medicine

Beta-lactam antimicrobials, commonly used in both veterinary and human medicine, generally present short biologic half-lives, whereas their activity is enhanced as pathogen exposure is prolonged. These properties necessitate multiple-dose regimens of standard dosage forms, thereby hampering pet owner adherence, frequently resulting in therapeutic failure. This study presents a novel controlled-release gastroretentive oral drug delivery system for beta-lactams with which single-dose administration provides an effective antimicrobial course, optimizing pharmacokinetic (PK)-pharmacodynamic (PD) profiles, minimizing adverse effects and emergence of antimicrobial resistance and facilitating adherence. Our prototype sustained-delivery swelling-tablet (SDST), based on a degradable hydrophilic polymeric matrix, was designed to enable continuous input of these drugs to their absorption sites over several days. Several SDST formulations of the beta-lactam amoxicillin were evaluated in in vitro dissolution studies. Two formulations were selected for further in vivo canine studies, for determination of gastric retention and PK-PD profiling. Prolonged gastric retention times maintaining allowed for maintained effective drug concentrations against many clinically relevant pathogens for more than 48 h for one formulation and more than 5 days for the other. Both SDST formulations offer significant advantages over standard immediate-release therapy in achieving PK-PD goals and enhancing adherence. The prototypical formulations represent a novel platform which may be modified to meet various clinical requirements.