Abstract

This study aimed to develop a solvent removal-based in situ forming gel (ISG) loaded with salicylic acid (SAL) using myristic acid (MYR) as a matrix-forming agent. SAL-loaded MYR-based ISGs were prepared using N-methyl-2-pyrrolidone (NMP) or dimethyl sulfoxide (DMSO) as solvents and evaluated for physicochemical properties, matrix formation behavior, mechanical characteristics, and in vitro drug release. Increasing MYR content influenced viscosity, gel formation kinetics, and depot integrity, resulting in prolonged SAL release of up to 20 days in DMSO-based formulations. The release kinetics were best described by the Peppas–Sahlin model, indicating diffusion-dominated drug transport. The selected formulation containing 30% w/w SAL and 20% w/w MYR exhibited acceptable injectability, reproducible in situ matrix formation, and sustained drug retention. Antimicrobial testing confirmed that SAL retained biological activity against oral pathogens following incorporation into the ISG system, although solvent contributions to antimicrobial effects were also observed. These findings demonstrate the feasibility of a MYR-based ISG system in which SAL contributes to both therapeutic activity and matrix formation, supporting its potential for localized oral drug delivery.