Solid Tranilast Nanocrystal-Loaded Cationic Contact Lenses for Sustained Ocular Drug Delivery

Background/Objectives Conventional eye drops are the primary therapeutic option for ocular diseases; however, their clinical utility is hindered by several drawbacks, including limited bioavailability and suboptimal patient compliance. To overcome these challenges, we designed a sustained-release contact lens (CL) device loaded with tranilast (TRA) and determined whether the TRA-laden CL could provide sustained drug delivery to the lacrimal fluid and aqueous humor. Methods TRA nanocrystals were prepared using the bead-milling approach. Using three types of CLs (nonionic, anionic, and cationic), we prepared TRA-laden CLs by employing a combination of solid TRA nanocrystals and soaking methods under high-temperature and high-pressure conditions in an autoclave (the hThP method). Male Japanese albino rabbits (2-3 kg) were used to evaluate the CLs. Results Bead milling reduced the size of the solid TRA nanoparticles (STNs) to approximately 35-180 nm. The TRA-laden cationic CLs prepared using STNs and the hThP method contained a higher amount of TRA than those prepared using the corresponding conventional soaking method. The CLs prepared using the hThP method remained transparent after drug loading. Compared with nonionic and anionic CLs, cationic CLs had the highest drug-loading capacity and allowed for sustained drug release. Moreover, STNs were observed in the released TRA, with no corneal damage or light scattering detected in the rabbits' eyes. TRA-laden cationic CLs prepared using the hThP method achieved sustained and higher drug delivery into the lacrimal fluid and aqueous humor than those prepared using the conventional soaking method. Conclusions Our findings suggest that TRA-laden cationic CLs prepared using STNs and the hThP method can overcome the challenges associated with the conventional soaking method, including low drug uptake and high burst release.