Ex Vivo Characterization and In Vivo Nasal Delivery of Ropinirole-Loaded PEO-b-PCL/Tween 80/β-Cyclodextrin Systems in C57BL/6J Mice

Intranasal administration is a promising drug delivery route enabling precise and rapid central nervous system targeting. In our previous work, twelve hybrid colloidal dispersions were developed, consisting of synthetic poly(ethylene-oxide)-b-poly(ε-caprolactone) (PEO-b-PCL) block copolymers with an increasing proportion of the hydrophobic PCL segment, Tween 80 (Tw80) and β-cyclodextrin derivatives (βCD), either methyl-β-CD (MβCD) or hydroxy-propyl-β-CD (HPβCD) for IN delivery of ropinirole hydrochloride (RH). Colloidal dispersions were prepared at different weight ratios (system/RH equal to 10:1 and 10:5), characterized and evaluated in vitro. The aim of this study is to evaluate the ex vivo permeation through rabbit nasal mucosa and determine the pharmacokinetic parameters of RH, when administered intranasally as a colloidal dispersion, compared with oral and intranasal RH solutions in C57BL/6J mice. Ex vivo permeation studies showed that all formulations significantly enhanced RH permeation compared to the pure RH solution (0.5 mg/mL, pH 5.6). Among them, F4 (PEO-b-PCL1/Tw80/HPβCD)/RH 10:5 was selected for further investigation. Pharmacokinetic analysis showed that F4 significantly enhanced both systemic and brain exposure of RH, achieving higher serum AUC and Cmax values, despite a 3-fold lower administered dose compared to the oral dose. It showed high systemic (Frel(Serum) = 1815%) and brain (Frel(Brain) = 363%) relative bioavailability compared with oral administration, underscoring its potential as an intranasal delivery system for efficient CNS targeting.