Optimizing Ocular Therapy: A Synergistic Approach with Thermosensitive Poloxamer 407 and Chitosan in In Situ Gel Formulation

Thermosensitive in situ gels in ocular drug delivery present a breakthrough in optimizing therapeutic outcomes. Responsive to physiological temperature, these gels undergo a transition from liquid to gel upon contact with the ocular surface. This unique property enhances drug bioavailability and extends retention time, overcoming challenges posed by rapid tear turnover. The gel viscosity promotes sustained drug release, minimizing the need for frequent administrations. In this study, a thermosensitive polymer base of poloxamer 407 was combined with chitosan to produce an in situ levofloxacin gel. Characterisation was carried out to see the effect of both polymers on the physicochemical properties of the resulting gel such as appearance, pH, gelation time and temperature, viscosity, and drug release. Attenuated Total Reflector (ATR) spectroscopy was employed to investigate the molecular interactions. Subsequently, the antibacterial activity was comparatively evaluated with a market product. This study aimed to develop Levofloxacin (LFX) in situ gel using poloxamer 407 (PLX407) and chitosan (CHT). Both polymers significantly influenced gelation characteristics, aligning with physiological eye mucosa temperature (34°C). PLX407's thermosensitivity played a vital role in gelation, decreasing solubility with temperature rise. Synergistic involvement of PLX407 and CHT resulted in lower gelation temperatures and times with higher PLX407 concentrations. At low CHT concentrations (<0.4%), increased concentration decreased gelation time. CHT's ability to accelerate dehydration and form crosslinks enhanced gel strength. The drug release profile followed a first-order model, suggesting controlled release, but the Korsmeyer-Peppas model indicated a super case II mechanism. In practice, shear forces and dilution lead to dissolution and erosion, but the dialysis membrane may restrict observation. This highlights the importance of practical relevance in experimental design.