Introduction: Ropinirole (RP), is a selective dopamine agonist that is used alone or with
other medications to treat the symptoms of Parkinson’s disease (PD). RP has low bioavailability of
only about 50% due to the first-pass metabolism, and it requires frequent dosing during oral administration.
Aim: The objective of the current research was to develop RP-loaded solid lipid nanoparticles (RP-
SLNs), nanostructured lipid carriers (RP-NLCs), and their corresponding hydrogels (RP-SLN-C
and RP-NLC-C) that could enhance RP therapeutic outcomes during PD treatment.
Methods: RP nanoparticles were prepared by homogenization followed by probe sonication and optimized
based on particle size, polydispersity index (PDI), zeta potential (ZP), % assay, % entrapment
efficiency, and in vitro release studies. Optimized formulations were converted into hydrogel
formulations using Carbopol 934 as a gelling polymer and optimized based on rheological and release
characteristics. Optimized formulations were further evaluated using differential scanning
calorimetry (DSC), powder X-ray diffractometry (PXRD), scanning electron microscopy (SEM),
freeze-drying, and stability study at refrigerated and room temperatures.
Results: The optimized RP-SLN formulation showed particle size and entrapment efficiency of
213.5±3.8 nm and 77.9±3.1% compared to 190.6±3.7 nm and 85.7±1.7% for optimized RP-NLC
formulation. PXRD supplemented and confirmed DSC results, RP was entrapped in a molecularly
dispersed state inside the core of the lipid nanocarrier. Furthermore, RP-loaded lipid nanocarriers
revealed a spherical shape in SEM images. In vitro release studies demonstrated sustained release
profiles for RP from SLNs, NLCs, and their hydrogels over 24 h. Optimized SLN, NLC, and nanocarrier-
loaded hydrogel formulations were stable over three months at 4ºC and 25ºC storage conditions.
Conclusion: Overall, the results demonstrated that lipid nanocarriers and their corresponding hydrogel
formulations can be considered as a topical drug delivery vehicle for RP during the treatment