Thiolated Hydroxypropyl-β-cyclodextrin: A Potential Multifunctional Excipient for Ocular Drug Delivery

The goal of this study was the design and evaluation of a thiolated cyclodextrin providing high drug solubilizing and mucoadhesive properties for ocular drug delivery. Hydroxypropyl-beta-cyclodextrin (HP-beta-CD) was thiolated via a microwave-assisted method, resulting in a degree of thiolation of 33%. Mucoadhesive properties of thiolated HP-beta-CD (HP-beta-CD-SH) were determined via rheological measurements and ex vivo studies on isolated porcine cornea. Due to thiolation of HP-beta-CD, a 2-fold increase of mucus viscosity and a 1.4-fold increase in residence time on isolated corneal tissue were achieved. After instillation, the mean precorneal residence time and AUC of dexamethasone (DMS) eye drops were 4-fold and 11.7-fold enhanced by HP-beta-CD-SH, respectively. Furthermore, in the presence of HP-beta-CD-SH, a constant high level of DMS in aqueous humour between 30 and 150 min after administration was observed. These results suggest that HP-beta-CD-SH is an excellent excipient for ocular formulations of poorly soluble drugs in order to prolong their ocular residence time and bioavailability.

Automated summary

The goal of this study was to design and evaluate a thiolated cyclodextrin for ocular drug delivery, which provides high drug solubilizing and mucoadhesive properties. The results showed that thiolated cyclodextrin significantly enhanced the precorneal residence time and bioavailability of dexamethasone eye drops, making it suitable for ocular formulations of poorly soluble drugs.