Evaluation of Long-Acting Injectable In-Situ Forming Gels through in vivo and in vitro MRI

Introduction: Long-acting injectable (LAI) drug products offer extended release of active compounds. By injecting poorly soluble compounds, dissolution is slowed for prolonged release. In situ forming gels (ISG), composed of active compound, polymer, and solvent, create a gel upon injection due to phase inversion. Understanding ISG behavior regarding drug release and tissue response in vivo is underexplored.^1,2 This study employs longitudinal MRI in rhesus non-human primates (NHPs) and phantom methods to analyze ISG systems, providing insights to inform clinical strategies and LAI discovery.