Preparation and characterization of topical letrozole nanoemulsion for breast cancer

Abstract

Letrozole (LZL) is a non-steroidal competitive aromatase enzyme system inhibitor. The aim of this study is to improve the permeation of LZL through the skin by preparing as nanoemulsion using various numbers of oils, surfactants and co-surfactant with deionized water. Based on solubility studies, mixtures of oleic acid oil and tween 80/ transcutol p as surfactant/co-surfactant (Smix) in different percentages were used to prepare nanoemulsions (NS). Therefore, 9 formulae of (o/w) LZL NS were formulated, then pseudo-ternary phase diagram was used as a useful tool to evaluate the NS domain at Smix ratios: 1:1, 2:1 and 3:1. All the prepared formulae were characterized for thermodynamic stability studies, zeta potential, droplet size, polydispersity index (PDI), % transmittance estimation, pH, % drug content, electro-conductivity and in vitro drug release. NS-7 (compose of 5% oleic acid, 45% Smix of 1:9 ratio and 50% water) was chosen as an optimum prepared formula for many reasons. Initially, it has a lower PDI (0.054), optimum droplet size (75.9 nm), highest transmittance percent (99.89±0.015%), high drug content (99.88%±0.03%), acceptable pH (5.96±0.025), highest electro-conductivity (230±1 μS/cm) and optimum drug release% (99.58±1.92) after 75 min in phosphate buffer (pH 6.8) compared to other NS formulations. One can conclude that preparation of LZL NS is an effective method for improving the permeation of LZL throught the skin. Copyrights