Formulation and evaluation of topical halofuginone gel using a novel ex vivo model

Abstract

Purpose: To formulate and study the kinetics of delivery and retention of three  halofuginone (HF) gels via different wall layers of an ex vivo model mimicking  urethral tissue.
Methods: Three HF hydrogels (a, b and c) of the same concentration (0.03 % w/v) incorporating different levels of sodium carboxymethyl cellulose (Na-CMC), were prepared. The viscosity of the different gels was studied at 37 °C and at room temperature. The release of HF from these hydrogels and its diffusion into urethral tissue were evaluated using a new ex vivo model mimicking human urethral tissue. The amount of HF was determined by HPLC method.
Results: The release of HF increased with increasing viscosity and duration of contact. Gel c showed the best drug release after 2 h of diffusion, with 65.7 % HF in the wall of the ureter. The model showed a uniform distribution of the drug throughout the ureter tissue. In comparison, HF was not detected in the receiver compartment until 2 h.
Conclusion: Topical HF gel application is a suitable solution for the potential treatment of urethral stricture and/or recurrence. The formulation and  characterization of the ureter model should facilitate the development of new therapeutics for urethral diseases.

Keywords: Halofuginone gel, Urethra, Wall diffusion, Urethral stenosis