Abstract
Purpose: It is necessary
for local anesthetics to pass through the stratum corneum to provide rapid pain
relief. Many techniques have been reported to enhance intradermal penetration
of local anesthetics such as vesicular lipid carriers. Ethosomes are lipid
vesicles containing phospholipids, ethanol at relatively high concentration. We hypothesized that synergistic effects of
phospholipids and high concentration of ethanol in formulation could accelerate
penetration of nanoethosomes in deep layers of skin.
Methods: Lidocaine-loaded
nanoethosomes were prepared and characterized by size and zeta analyzer,
scanning electron microscopy (SEM) and X-ray diffractometer (XRD). Furthermore,
encapsulation efficiency (EE), loading capacity (LC), and skin penetration
capability were evaluated by in vitro and in vivo experiments.
Results: results showed
that the particle size, zeta potential, EE and LC of optimum formulation were
105.4 ± 7.9 nm, -33.6 ± 2.4 mV, 40.14 ± 2.5 %, and 8.02 ± 0.71 respectively.
SEM results confirmed the non-aggregated nano-scale size of prepared
nanoethosomes. Particle size of ethosomes and EE of Lidocaine were depended on
the phospholipid and ethanol concentrations. XRD results demonstrated the drug
encapsulation in amorphous status interpreting the achieved high drug EE and LC
values. In vitro and in vivo assays confirmed the appropriate
skin penetration of Lidocaine with the aid of nanoethosomes and existence of
deposition of nanoethosomes in deep skin layers, respectively.
Conclusion: The developed nanoethosomes are proposed as a suitable
carrier for topical delivery of anesthetics such as Lidocaine.