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

Area of Science:

• Pharmaceutical Sciences
• Biomaterials Science
• Ocular Drug Delivery

Background:

• Developing effective ocular drug delivery systems is challenging due to rapid precorneal clearance.
• Poorly soluble drugs require formulation strategies to improve bioavailability.
• Cyclodextrins are known for their drug solubilizing capabilities.

Purpose of the Study:

• To design and evaluate a thiolated cyclodextrin (HP-β-CD-SH) for enhanced ocular drug delivery.
• To improve drug solubilization and mucoadhesive properties.
• To increase ocular residence time and bioavailability of drugs.

Main Methods:

• Hydroxypropyl-β-cyclodextrin (HP-β-CD) was thiolated using a microwave-assisted method.
• Mucoadhesive properties were assessed via rheological measurements and ex vivo corneal studies.
• In vivo ocular delivery of dexamethasone (DMS) using HP-β-CD-SH was evaluated.

Main Results:

• Thiolation resulted in a 33% degree of thiolation for HP-β-CD.
• HP-β-CD-SH demonstrated a 2-fold increase in mucus viscosity and a 1.4-fold increase in corneal residence time.
• HP-β-CD-SH enhanced the precorneal residence time (4-fold) and AUC (11.7-fold) of dexamethasone eye drops.
• Sustained high levels of dexamethasone in aqueous humor were observed for 120 minutes.

Conclusions:

• Thiolated HP-β-CD (HP-β-CD-SH) exhibits significant mucoadhesive properties.
• HP-β-CD-SH effectively enhances ocular drug delivery by prolonging residence time and improving bioavailability.
• This excipient shows promise for formulating poorly soluble drugs in ophthalmic applications.