Preparation and evaluation of thermo-sensitive hyaluronic acid/thiolated chitosan ophthalmic complex nano-hydrogel

The aim of this research was to prepare and evaluate thermo-sensitive complex nano-hydrogel(HP/CN)comprising of hyaluronic acid derivative(HA-PN)and thiolated chitosan(CMCS-NAC)for the ocular delivery of cyclosporine A(CsA). The CsA complex nano-hydrogel(CsA HP/CN)was prepared by incubation, then the size, Zeta potential, low critical solution temperature(LCST)and drug-loading capacity were characterized. The rabbit eye irritation effect, tissue adhesiveness and pharmacokinetic studies were investigated to evaluate the ocular compatibility and bioavailability of CsA HP/CN formulation. CsA HP/CN was found to be spherical in shape with a mean diameter of(122. 7±17. 8)nm, the Zeta potential of -(27. 87±2. 16)mV and LCST of 28. 4 °C with a drug-loading capacity up to 15. 08%. The rabbit eye irritation experiment showed no irritation on rabbit eyes. The CsA HP/CN group displayed significantly higher adhesive effect(1. 97- fold)on eye tissue as compared to the control group(drug carrier alone)after 15 min of ocular administration. Rabbit eyes pharmacokinetic data confirmed significantly higher AUC(1. 67- fold)and MRT(5. 17- fold)compared to the control group. Therefore, CsA HP/CN with small particle size and high drug loading capacity could obviously extend the drug retention time and increase its bioavailability on eyes, thus with potential application prospect in ocular drug delivery system.