Maximum Loaded Amorphous Azithromycin Produced Using the Wetness Impregnation Method with Fractional Steps for Dermal...

Area of Science:

• Pharmaceutical Sciences
• Materials Science
• Infectious Disease Research

Background:

• Lyme disease prevention requires effective drug delivery systems.
• Azithromycin is a key antibiotic for treating Lyme disease.
• Improving azithromycin's dermal bioavailability is crucial for topical formulations.

Purpose of the Study:

• To develop and characterize azithromycin-loaded mesoporous silica nanoparticles.
• To evaluate the stability and dermal penetration of the azithromycin-silica formulation.
• To assess its potential as a prophylactic agent against Lyme disease.

Main Methods:

• Mesoporous silica (Davisil SP53D-11920) loaded with azithromycin using wetness impregnation with fractional steps (WIFS).
• Incorporation into a 5% hydroxypropyl cellulose gel.
• Characterization of drug loading and stability using X-ray diffraction (XRD).
• Assessment of kinetic solubility and *ex vivo* skin penetration using porcine ear skin.

Main Results:

• Maximum azithromycin loadings achieved were 32.0% and 33.2% w/w.
• Amorphous azithromycin state stability confirmed for 24 months in silica and 18 months in gel at 4°C.
• Enhanced kinetic solubility (1,300 μg/mL vs. 93 μg/mL) and superior skin penetration compared to raw azithromycin.
• Outperformed nanocrystals and ethanol-based formulations in dermal bioavailability.

Conclusions:

• Azithromycin-loaded mesoporous silica prepared by WIFS is a stable and effective dermal formulation.
• The formulation exhibits significantly enhanced dermal bioavailability for Lyme disease prophylaxis.
• This novel silica-based system presents a promising strategy for topical prevention of Lyme disease.