Co-emulsified Alginate-Eudragit Nanoparticles: Potential Carriers for Localized and Time-defined Release of Tenofovir in the Female Genital Tract

Abstract

This research aimed to explore the possibilities of Eudragit S100 (ES100) and sodium alginate as carriers for tenofovir disoproxil fumarate (TDF) in the female genital tract. Alginate and alginate-ES100 nanoparticles were prepared using the ionic gelation and emulsion/gelation complexation method, respectively. The nanocarriers were tested using morphological, physicochemical, in vitro drug release, and cytotoxicity analyses. In SEM and TEM images, the presence of spherical and uniformly distributed nanoparticles was revealed. The FTIR spectrum showed that alginate and calcium chloride interacted due to ionic bonds linking divalent calcium ions and the -COO- of alginate groups. Alginate and ES100 interacted via the ester C=O amide stretching. The results obtained from XRD and DSC, on the other hand, revealed a favorable interaction between sodium alginate and ES100 polymers, as evidenced by the crystallization peaks observed. Under experimental design analysis and optimization, overall size distribution profiles ranged from 134.9 to 228.0 nm, while zeta potential results showed stable nanoparticles (−17.8 to −38.4 MV). The optimal formulation exhibited a maximum cumulative in vitro release of 72% (pH 4.2) up to 96 h. The cytotoxicity tests revealed the safety of TDF-loaded nanoparticles on vaginal epithelial cells at concentrations of 0.025 mg/mL, 0.5 mg/mL, and 1 mg/mL for 72 h. These results indicated that alginate-ES100 nanoparticles have the potential to preserve and sustain the release of the TDF drug in the FGT. The future goal is to develop a low-dose non-toxic microbicide that can be administered long term in the vagina to cater to both pregnant and non-pregnant HIV patients.