Carbopol-coated mucoadhesive PLGA nanoparticles for the sustained delivery of pilocarpine in the buccal cavity

Abstract

Objectives This study investigates a new nanoparticulate (NP) formulation for local buccal administration of pilocarpine (PIL) to treat xerostomia, aiming to improve patient compliance and reduce side effects. Methods PIL-loaded NPs were prepared using poly (d,l-lactic-co-glycolic acid) (PLGA) as a matrix/carrier and carbopol (CRB) as a mucoadhesive agent at various concentrations at ratios of 0.05, 0.10 and 0.15% w/v. The NPs were characterized in terms of size, morphology, drug loading, thermophysical and physicochemical properties, in vitro dissolution performance, and mucoadhesion. Key findings Smooth spherical drug-loaded NPs (200-300 nm) were prepared in all cases. CRB coating did not impact particle size or polydispersity index but increased NPs' negative surface charges. Good storage stability, high production yields (72.0-83.7%), and adequate drug loading efficiencies (9.0-9.7%) were achieved, in all cases. Differential scanning calorimetry and powder X-ray diffraction measurements confirmed the amorphous drug dispersion, while attenuated total reflectance-Fourier transform infrared spectroscopy studies revealed strong molecular interactions between the matrix/carrier and the mucoadhesive agent. In-vitro drug release studies showed sustained release profiles for all NPs, whereas the application of a CRB-coating enhanced mucoadhesion performance through the formation of electrostatic ionic interactions and physical entanglement with mucin. Conclusions The preparation of a new PLGA-based NP formulation may present itself as a promising strategy for the buccal administration of PIL, while the use of CRB coating could be considered as a useful approach for enhancing the mucus adhesion of NPs.