Solid Lipid Nanoparticles Formulated for Transdermal Aconitine Administration and Evaluated In Vitro and In Vivo.

In this study, solid lipid nanoparticles were formulated for transdermal delivery of aconitine to improve its safety and permeability. Aconitine-loaded solid lipid nanoparticles were formulated as an oil-in-water microemulsion. Drug encapsulation efficiencies for these formulations were higher than 85%, and correlated positively with levels of surfactant and oil matrix. The size of the solid lipid nanoparticles was increased with an increase of the oil matrix, and reduction of the surfactant levels. Compared with an ethanol tincture, all the tested solid lipid nanoparticle formulations achieved improved transdermal fluxes and drug deposition in skin in vitro. Real-time monitoring of drug distribution in rat dermis using in vivo microdialysis showed that aconitine concentration was markedly higher following application of solid lipid nanoparticles, compared to tincture, throughout the experimental period. A regional comparison of rat skin found that application of solid lipid nanoparticles to the scapular region resulted in higher AUC(0-t) and C(max), compared to those achieved with application to the abdomen or chest (p < 0.05). In contrast, the application to the chest resulted in the lowest AUC(0-t) and C(max). Together with findings of a structural study of the skin, these results indicated that the drug accumulated more readily in thicker skin regions, and to a lesser extent in well-perfused skin, because of drug transfer to capillaries. The superior transdermal permeability of aconitine-loaded solid lipid nanoparticles contributed to stronger anti-inflammatory and analgesic effects on mouse in vivo models of pain than the tincture (p < 0.05). In vitro and in vivo studies indicated that smaller particle sizes of solid lipid nanoparticles enhanced the transdermal permeability of aconitine, which can promote drug efficacy, reduce administration time, and improve medication safety.

Preparation and evaluation of microemulsion-based transdermal delivery of total flavone of rhizoma arisaematis.

The aims of the present study were to investigate the skin permeation and cellular uptake of a microemulsion (ME) containing total flavone of rhizoma arisaematis (TFRA), and to evaluate its effects on skin structure. Pseudo-ternary phase diagrams were constructed to evaluate ME regions with various surfactants and cosurfactants. Eight formulations of oil-in-water MEs were selected as vehicles, and in vitro skin-permeation experiments were performed to optimize the ME formulation and to evaluate its permeability, in comparison to that of an aqueous suspension. Laser scanning confocal microscopy and fluorescent-activated cell sorting were used to explore the cellular uptake of rhodamine 110-labeled ME in human epidermal keratinocytes (HaCaT) and human embryonic skin fibroblasts (CCC-ESF-1). The structure of stratum corneum treated with ME was observed using a scanning electron microscope. Furthermore, skin irritation was tested to evaluate the safety of ME. ME formulated with 4% ethyl oleate (weight/weight), 18% Cremophor EL (weight/weight), and 18% Transcutol P, with 1% Azone to enhance permeation, showed good skin permeability. ME-associated transdermal fluxes of schaftoside and isoschaftoside, two major effective constituents of TFRA, were 3.72-fold and 5.92-fold higher, respectively, than those achieved using aqueous suspensions. In contrast, in vitro studies revealed that uptake by HaCaT and CCC-ESF-1 cells was lower with ME than with an aqueous suspension. Stratum corneum loosening and shedding was observed in nude mouse skin treated with ME, although ME produced no observable skin irritation in rabbits. These findings indicated that ME enhanced transdermal TFRA delivery effectively and showed good biocompatibility with skin tissue.

Comparison of ethosomes and liposomes for skin delivery of psoralen for psoriasis therapy.

Recent reports have indicated that psoriasis may be caused by malfunctioning dermal immune cells, and psoralen ultraviolet A (PUVA) is an effective treatment for this chronic disease. However, conventional topical formulations achieve poor drug delivery across patches of psoriasis to their target sites. The present study describes the development of a novel psoralen transdermal delivery system employing ethosomes, flexible vesicles that can penetrate the stratum corneum and target deep skin layers. An in vitro skin permeation study showed that the permeability of psoralen-loaded ethosomes was superior to that of liposomes. Using ethosomes, psoralen transdermal flux and skin deposition were 38.89±0.32 µg/cm(2)/h and 3.87±1.74 µg/cm(2), respectively, 3.50 and 2.15 times those achieved using liposomes, respectively. The ethosomes and liposomes were found to be safe following daily application to rat skin in vivo, for 7 days. The ethosomes showed better biocompatibility with human embryonic skin fibroblasts than did an equivalent ethanol solution, indicating that the phosphatidylcholine present in ethosome vesicles improved their biocompatibility. These findings indicated that ethosomes could potentially improve the dermal and transdermal delivery of psoralen and possibly of other drugs requiring deep skin delivery.