Effect of zeta potential of innovative lipid nanocapsules on triamcinolone transdermal delivery

Two pegylated lipid nanocapsules for triamcinolone transdermal delivery were designed. Both present a size close to 50 nm and a single monomodal distribution in particle size (PI < 0.2), with a zeta potential of − 20 ± 2 and + 18 ± 1, respectively. The triamcinolone encapsulation efficacy varied between 68 and 80%. They proved to be stable under storage conditions (4 °C) for at least 6 months and at a physiological temperature, using different media, for 48 h. Also, they were shown not to affect cell viability at the concentrations used. For ex vivo transdermal experiments, newborn pig skin was used. With respect to the triamcinolone transdermal penetration, the nanocapsules were demonstrated to have an absorption promoting effect, both when the drug nanocapsules were in solution or loaded into the hydrogel, quantifying between 2 and 15 times more absorbed drug than the control. In addition, regarding the triamcinolone retained in the skin, it is observed that lipid nanocapsules act as triamcinolone promoters when the nanosystems were in solution and when they were included in the hydrogel. This vehicle showed a greater triamcinolone reservoir effect in comparison to the nanocapsules, proving to be a good vehicle to formulate triamcinolone transdermal delivery. Graphical abstract