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7th International Symposium on ADVANCES IN PHARMACEUTICAL ANALYSIS (APA 2025), Ankara, Turkey, 24 - 27 August 2025, pp.122, (Full Text)
Introduction: Nanoparticles (NPs) are promising drug delivery carriers due to their potential to enhance bioavailability,
extend circulation time, and enable controlled release. The double emulsion solvent evaporation (DESE) technique is
particularly suitable for encapsulating active pharmaceutical ingredients (APIs). Eudragit RS100 (ERS), a cationic
polymethacrylate, is commonly used in NP formulations owing to its pH-independent solubility and permeability. This study
aimed to develop and optimize ERS-based NPs using DESE and to investigate the effects of key formulation parameters—
surfactant type and concentration, and probe sonication time—on particle size (PS), polydispersity index (PDI), and zeta
potential (ZP). Additionally, the encapsulation efficiency of a model hydrophilic drug, brimonidine tartrate (BT), used in
ocular glaucoma treatment, was evaluated [1-3].
Materials and Methods: A total of 29 nanoparticles (22 blank and 7 BT-loaded) were prepared using the W1/O/W2 DESE
method. Each formulation contained 60 mg of ERS, with methanol or acetone as the organic phase. The aqueous phases
included either PVA or Poloxamer 188 (P188) (0.5–1.5% w/v), and selected formulations contained 20 mg Span 60 for
enhanced emulsion stability. Emulsification was performed via probe sonication (30–120 s, 60% amplitude). PS, PDI, ZP
were characterized by DLS, and BT-loaded NPs were compared with their blank counterparts to assess the effect of drug
loading [1-3].
Results: First of all, when methanol was used as the organic solvent, the NP structure could not be obtained. When PVA
was used as a stabilizer, acetone as the organic solvent failed to produce stable NPs. These systems showed incomplete
or irregular NP formation, high PDI values, and signs of aggregation or sedimentation. Conversely, NPs employing P188
in both the W1 and W2 phases produced stable and uniform NPs, especially when acetone was used as the organic phase
and Span 60 was included. These successful blank NPs displayed PSs ranging from 97.1 to 189.1 nm, with PDI values
below 0.574, suggesting a narrow PS distribution. Moreover, ZPs were consistently positive, ranging from +16.3 to +25.1
mV, indicating excellent electrostatic stability and surface charge appropriate for interaction with negatively charged
mucosal membranes. Among these, the V-Blank-NP demonstrated the most favorable properties, with a PS of 177.7±0.8
nm, a PDI of 0.326±0.032, and a ZP of +20.5±0.2 mV. The BT-loaded NPs, which included BT(6 mg), exhibited a moderate
increase in PS and a slight increase in PDI. The positive ZP was maintained, with values ranging between +11.3 and +19.4
mV, confirming that drug incorporation did not significantly compromise colloidal stability. The best-performing BT-loaded
NP was V-BT-NP, which exhibited a PS of 180.2±3.4 nm, a PDI of 0.369±0.031, and a ZP of +19.1±0.6 mV.
Conclusion: This study successfully demonstrates the design, development, and optimization of positively charged ERS
based NPs prepared using the DESE technique. Our findings indicate that P188 is a superior stabilizer compared to PVA
in producing stable NPs with desirable physicochemical properties. Acetone was identified as a more appropriate solvent
than methanol and Span 60 contributed to further enhancing emulsion stability and particle uniformity. Importantly, BT was
effectively loaded into the NP system without significant disruption to PS, homogeneity, or surface charge. The optimized
NP, V-BT-NP, demonstrated excellent potential for further development in ocular or mucosal drug delivery applications,
particularly for hydrophilic, cationic active pharmaceutical ingredients.
Acknowledgements
This study was supported by Scientific Research Coordination Unit of Anadolu University under the project number TYL-
2025-2924 (Project ID: 2924).