FORMULATION AND CHARACTERIZATION OF BETULIN-LOADED MICROEMULSION FOR ANTI-GOUT THERAPY

SWATI BHASKARRAO SURDKAR; NAGARAJU BANDARU

doi:10.22159/ajpcr.2025v18i11.56349

Authors

SWATI BHASKARRAO SURDKAR Department of Pharmaceutical Quality Assurance, School of Pharmaceutical Sciences, Sandip University, Nashik, Maharashtra, India.
NAGARAJU BANDARU Department of Pharmacology, School of Pharmaceutical Sciences, Sandip University, Nashik, Maharashtra, India. https://orcid.org/0000-0003-2059-4849

DOI:

https://doi.org/10.22159/ajpcr.2025v18i11.56349

Keywords:

Betulin, Microemulsion, Gouty arthritis, Anti-inflammatory, Transdermal drug delivery

Abstract

Objectives: The study aimed to formulate and evaluate a betulin-loaded microemulsion for enhanced topical anti-gout efficacy and skin retention, using diclofenac diethylamine emulgel 1% as the positive control.

Methods: Betulin microemulsions were prepared using medium-chain triglyceride oil, Tween 80, and ethanol through the phase inversion method. Physicochemical characterization was performed through droplet size analysis, zeta potential, viscosity, pH, and Fourier-transform infrared spectroscopy studies. Pseudo-ternary phase diagrams were constructed to optimize composition. Ex vivo permeation and skin retention were assessed using porcine skin in Franz diffusion cells, followed by skin homogenization and extraction. Anti-inflammatory efficacy was evaluated in a monosodium urate (MSU) crystal-induced gouty arthritis model in mice, while skin irritation studies were conducted in guinea pigs. Statistical analysis was performed using one-way analysis of variance followed by Dunnett’s test.

Results: The optimized microemulsion (10% oil, 20% surfactant, 10% co-surfactant, and 0.5% betulin) exhibited droplet size of 152±3.4 nm, polydispersity index of 0.218, and zeta potential of –28.5 mV. Ex vivo studies revealed cumulative permeation of 50.2±3.0 μg/cm2 at 24 h with 24.7±2.3% retention in the skin. In vivo, betulin microemulsion (1%) significantly reduced paw edema and pro-inflammatory cytokines (interleukin-1 beta and tumor necrosis factor-alpha), and improved weight-bearing distribution compared to the MSU group (***p<0.001), demonstrating efficacy comparable to diclofenac emulgel. No dermal irritation was observed in guinea pigs.

Conclusion: Betulin microemulsion exhibited favorable physicochemical properties, high skin retention, and potent topical anti-inflammatory activity in gout, with excellent dermal safety. These findings support its potential as a safe and effective topical delivery system for the management of gouty arthritis.

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