Liposomes skin lipids

Interaction of the liposomal lipids with cellular lipid bilayers or other lipid bilayers in the body (e.g. skin lipids) depends on the nature of the lipids in the liposome. In order to... 

M. Fresta and G. Puglisi, Corticosteroid dermal delivery with skin-lipid liposomes. J. Contr. Rel. 44 141-151 (1997). 

In a subsequent study, van Hal et al. [40] reported that a decrease in cholesterol content in liquid state bilayers, which increases bilayer fluidity, resulted in an increase in estradiol transport across SC. With confocal laser scanning microscopy, Meuwissen et al. examined the diffusion depth of gel- vs. liquid-state liposomes labeled with fluorescein-dipalmitoylphosphatidylethanolamine (fluorescein-DPPE) with human skin in vitro [41] (Figure 3) and rat skin in vivo [42] and found that the lipophilic label when applied in liquid-state bilayers onto the skin penetrated deeper into the skin than when applied in gel-state liposomes. Recently, Fresta and Puglisi [43] reported that corticosteroid dermal delivery with skin-lipid liposomes was more effective than delivery with phospholipid vesicles, both with respect to higher drug concentrations in deeper skin layers and therapeutic effectiveness. This is a very surprising result, because skin lipid liposomes are rigid and form stacks of lamellae on the surface of the skin [44]. From the previously mentioned studies it seems clear that the thermodynamic state of the bilayer plays a crucial role in the effect of vesicles on dmg transport rate across skin in vitro. 

Negatively chained pectindecorated liposomes fluidize stratum corneum via rq>ulsion against skin lipid... 

The development of monoalkyl phosphate as a low skin irritating anionic surfactant is accented in a review with 30 references on monoalkyl phosphate salts, including surface-active properties, cutaneous effects, and applications to paste and liquid-type skin cleansers, and also phosphorylation reactions from the viewpoint of industrial production [26]. Amine salts of acrylate ester polymers, which are physiologically acceptable and useful as surfactants, are prepared by transesterification of alkyl acrylate polymers with 4-morpholinethanol or the alkanolamines and fatty alcohols or alkoxylated alkylphenols, and neutralizing with carboxylic or phosphoric acid. The polymer salt was used as an emulsifying agent for oils and waxes [70]. Preparation of pharmaceutical liposomes with surfactants derived from phosphoric acid is described in [279]. Lipid bilayer vesicles comprise an anionic or zwitterionic surfactant which when dispersed in H20 at a temperature above the phase transition temperature is in a micellar phase and a second lipid which is a single-chain fatty acid, fatty acid ester, or fatty alcohol which is in an emulsion phase, and cholesterol or a derivative. 

Liposome-encapsulated tretinoin has been tested in hairless mice as well as in man. The animal experiment has demonstrated the favorable uptake of the retinoid, whereas the liposomal lipids appear to be more retained in the homy layer [53], Moreover, with phospholipid-based liposomes belonging to the gel-state type, tretinoin penetration in murine skin appears to be confined to the epidermis [54] and, thus, is close to prednicarbate penetration described above. In patients with acne vulgaris, we could demonstrate a better tolerability of liposomal tretinoin as compared to a commercial gel while efficiency remains the same [55],... 

Cevc G, Schatzlein A, Richardsen H, Vierl U. Overcoming semipermeable barriers, such as the skin, with ultradeformable mixed lipid vesicles, transfersomes, liposomes, or mixed lipid micelles. Langmuir 2003 19 10753-10763. 

Cevc G. Transfersomes, liposomes and other lipid suspensions on the skin permeation enhancement, vesicle penetration, and transdermal drug delivery. Crit Rev Ther Drug... 

Liquid crystals, liposomes, and artificial membranes. Phospholipids dissolve in water to form true solutions only at very low concentrations ( 10-10 M for distearoyl phosphatidylcholine). At higher concentrations they exist in liquid crystalline phases in which the molecules are partially oriented. Phosphatidylcholines (lecithins) exist almost exclusively in a lamellar (smectic) phase in which the molecules form bilayers. In a warm phosphatidylcholine-water mixture containing at least 30% water by weight the phospholipid forms multilamellar vesicles, one lipid bilayer surrounding another in an "onion skin" structure. When such vesicles are subjected to ultrasonic vibration they break up, forming some very small vesicles of diameter down to 25 nm which are surrounded by a single bilayer. These unilamellar vesicles are often used for study of the properties of bilayers. Vesicles of both types are often called liposomes.75-77... 

Dermal and transdermal delivery requires efficient penetration of compounds through the skin barrier, the bilayer domains of intercellular lipid matrices, and keratin bundles in the stratum corneum (SC). Lipid vesicular systems are a recognized mode of enhanced delivery of drugs into and through the skin. However, it is noteworthy that not every lipid vesicular system has the adequate characteristics to enhance skin membrane permeation. Specially designed lipid vesicles in contrast to classic liposomal compositions could achieve this goal. This chapter describes the structure, main physicochemical characteristics, and mechanism of action of prominent vesicular carriers in this field and reviews reported data on their enhanced delivery performance. 

An early study confirmed that occlusion is detrimental to transfersome penetration enhancement ability. The results of this study clearly demonstrated that, under the occlusive conditions, murine skin permeation of fluorescently labeled lipids from transfersomal suspensions and liposomes is comparable [67]. Furthermore, Guo et al. reported that the vesicles failed to transfer detectable quantities of cyclosporin A through the hydrated abdominal mice skin [71],... 

Although frequently referred to as a kind of liposomes, ethosomes are very different from other lipid vesicles by their composition, structure, mechanism of action, and delivery properties. Ethosomal carriers contain soft lipid vesicles (mainly composed of phospholipids, ethanol, and water) in a hydroethanolic milieu. They have appropriate features, designed to allow for enhanced delivery by passive transport to the deep skin strata and through the skin [86-90], Their delivery enhancing properties can be modulated by changes in the composition and structure. Ethosomes, invented by Touitou [86-88], were so named to emphasize the... 

FITC-Bac) delivered in vivo from ethosomes, penetrated the rat skin through the intercor-neocyte pathways, which typically exist along the lipid domain of the stratum corneum [95] (Figure 13.7). In contrast, significantly lower fluorescence staining of the intercellular penetration pathway and no inter- or intracorneocyte fluorescence were observed with FITC-Bac hydroethanolic solution and liposomes, respectively. 

El Maghraby, G.M., A.C. Williams, and B.W. Barry. 2000. Skin delivery of oestradiol from lipid vesicles Importance of liposome structure. Int J Pharm 204 159. 

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