Liposomes — microscopic phospholipid bubbles with a bilayered membrane structure — have received a lot of attention during the past 30 years as pharmaceutical carriers of great potential. More recently, many new developments have been seen in the area of liposomal drugs — from clinically approved products to new experimental applications, with gene delivery and cancer therapy still being the principal areas of interest. For further successful development of this field, promising trends must be identified and exploited, albeit with a clear understanding of the limitations of these approaches.

Recent advances with liposomes as pharmaceutical carriers.

Liposomal drug delivery systems: from concept to clinical applications.

The rapid recognition of intravenously injected colloidal carriers, such as liposomes and polymeric nanospheres from the blood by Kupffer cells, has initiated a surge of development for "Kupffer cell-evading" or long-circulating particles. Such carriers have applications in vascular drug delivery and release, site-specific targeting (passive as well as active targeting), as well as transfusion medicine. In this article we have critically reviewed and assessed the rational approaches in the design as well as the biological performance of such constructs. For engineering and design of long-circulating carriers, we have taken a lead from nature. Here, we have explored the surface mechanisms, which affords red blood cells long-circulatory lives and the ability of specific microorganisms to evade macrophage recognition. Our analysis is then centered where such strategies have been translated and fabricated to design a wide range of particulate carriers (e.g., nanospheres, liposomes, micelles, oil-in-water emulsions) with prolonged circulation and/or target specificity. With regard to the targeting issues, attention is particularly focused on the importance of physiological barriers and disease states.

Long-Circulating and Target-Specific Nanoparticles: Theory to Practice

Doxil®--the first FDA-approved nano-drug: lessons learned.

Injectable nanoparticulate carriers have important potential applications such as site-specific drug delivery or medical imaging. Conventional carriers, however, cannot generally be used because they are eliminated by the reticulo-endothelial system within seconds or minutes after intravenous injection. To address these limitations, monodisperse biodegradable nanospheres were developed from amphiphilic copolymers composed of two biocompatible blocks. The nanospheres exhibited dramatically increased blood circulation times and reduced liver accumulation in mice. Furthermore, they entrapped up to 45 percent by weight of the drug in the dense core in a one-step procedure and could be freeze-dried and easily redispersed without additives in aqueous solutions.

https://science.sciencemag.org/content/sci/263/5153/1600.full.pdf

Biodegradable long-circulating polymeric nanospheres

Lipid vesicles penetrate into intact skin owing to the transdermal osmotic gradients and hydration force.

Liposomes for the sustained drug release in vivo

Particle size of liposomes influences dermal delivery of substances into skin.

Ultraflexible vesicles, Transfersomes, have an extremely low pore penetration resistance and transport therapeutic amounts of insulin across the intact mammalian skin.

Gabriele Blume

Papers

Lipid vesicles penetrate into intact skin owing to the transdermal osmotic gradients and hydration force.

Liposomes for the sustained drug release in vivo

Particle size of liposomes influences dermal delivery of substances into skin.

Ultraflexible vesicles, Transfersomes, have an extremely low pore penetration resistance and transport therapeutic amounts of insulin across the intact mammalian skin.

New, highly efficient formulation of diclofenac for the topical, transdermal administration in ultradeformable drug carriers, Transfersomes.