Chloramphenicol/sulfobutyl ether-ß-cyclodextrin complexes in an ophthalmic delivery system: prolonged residence time and enhanced bioavailability in the conjunctival sac.

Objective: Conventional chloramphenicol (CHL) eye drops are widely used anti-infection formulations for acute bacterial conjunctivitis. However, the therapeutic effects are limited by insufficient concentration in the conjunctival sac. Hence, the objective of this study is to formulate and develop novel CHL eye drops with improved topical concentrations by increasing the solubility and decreasing the transcorneal penetration. Research design and methods: CHL was included in the sulfobutyl ether-ß-cyclodextrin (SBE-ß-CD) using the freeze-drying method. Eye drops containing CHL/SBE-ß-CD complexes were prepared and evaluated for in vitro and in vivo studies. Results: The formation of CHL/SBE-ß-CD inclusion was confirmed by DSC, XRD, NMR, and SEM. The aqueous solubility of CHL was significantly enhanced, and the drug transcorneal penetration was inhibited after inclusion. The CHL/SBE-ß-CD displayed sustained release profiles. The tear fluid elimination kinetic study showed that the CHL/SBE-ß-CD eye drops had better ability to prolong the residence time, and significantly increase CHL concentration in the conjunctival sac. Besides, it was shown that CHL/SBE-ß-CD eye drops were nonirritating to rabbits' eyes. Conclusions: The SBE-ß-CD inclusions offer a potential alternative strategy for ocular administration of poorly water-soluble drugs in the conjunctival sac.