Engineering and characterisation of 3D-printed timolol maleate implants for long-acting glaucoma treatment

Timolol maleate (TM) is a nonselective β-blocker commonly used to treat ocular hypertension and glaucoma. Traditional formulations, such as eye drops and gel-forming solutions, often require frequent administration and may lead to systemic side effects and poor patient compliance. To address these challenges, this study investigated the fabrication and characterization of TM-loaded ocular implants via vat-polymerization 3D printing. The implants were fabricated using polyethylene glycol diacrylate (PEGDA) alone or in combination with polylactic acid/polyurethane acrylate (PLA/PUA) or poly(lactic-co-glycolic acid) (PLGA). The implants were characterized for their thermal properties, drug-release profiles, and biocompatibility. Fourier transform infrared (FTIR) spectroscopy confirmed the absence of significant chemical interactions between the TM and the polymers. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) revealed the thermal stability of the TM-loaded implants, with drug loading influencing the thermal properties. In vitro release studies over 180 days showed that drug release was proportional to the surface area-to-volume (SA/V) ratio of the implant. The release kinetics followed a diffusion-controlled mechanism, as described by the Korsmeyer-Peppas model. The biocompatibility study showed no significant cytotoxicity, with fibroblast viability exceeding 80%. These findings suggest that TM-loaded implants could provide a more effective, sustained-release alternative for glaucoma treatment.