LAUSR

Abstract Tacrolimus (TAC) or FK506 is a macrolide lactone isolated from the bacterial fermentation of Streptomyces tsukubaensis which belongs to the group of calcineurin inhibitors. Its main mechanism of action is to act on the immune system. In addition, this drug has been widely explored for skin disorders. However, TAC shows high molecular weight, high hydrophobicity, and low water solubility that can limit its ability to effectively permeate through the skin. Hence, it becomes imperative to develop a percutaneous drug delivery system for increasing its permeation in relation to the conventional ointment and for reducing the dose and the adverse effects as erythema, itching, and burning. Therefore, the aim of this work was to investigate the stability of colloidal suspensions of TAC-loaded poly(ԑ-caprolactone) (PCL) nanoparticles that were stored at room temperature for 120 days. In that sense, pH, particle size, polydispersity index (PDI), zeta potential, and Raman spectroscopy were performed. Significant decrease of pH (p 0.05) during the time interval investigated. Zeta potential presented statistically significant difference (p