Elastic liposomes

Elastic Liposomes for Topical and Transdermal Drug Delivery... 

Key words Colloids, Elastic liposomes, Liposomes, Transfersomes, Skin penetration enhancement. Drug carriers... 

A wide variety of compositions for elastic liposomes have been investigated. The following is based on a typical composition and method of preparation for a lipophilic drug such as estradiol. 

In general, elastic liposomes are prepared using similar methods to conventional liposomes, most commonly using the conventional rotary evaporation sonication method (26, 28-30). A typical preparation method is outlined ... 

The deformability of elastic liposomes is determined by assessment of the extrusion of the suspension through a filter membrane of defined pore size (50 nm) under pressure (24, 31). The amount of liposome suspension extruded is measured and the liposome size and shape are determined as previously described. For each liposome suspension, the mean standard deviation of... 

Physical stability is assessed by placing samples of the elastic liposome suspension into vials that are flushed with nitrogen and sealed. The vials are stored under varied conditions such as light protected or exposed, refrigerated and at room temperature. At different time periods (e.g. 10, 20, 30 days and monthly up to 6 months) the samples are analysed for particle size and residual drug content. 

A suitable animal model can be used for in vivo pharmacokinetic assessment of a topically applied elastic liposome formulation. Rats and mice are most common but tend to provide an over-estimate compared to human skin as the skin is more permeable. Piglets provide a closer approximation to human skin permeability and have been used for some evaluations of elastic liposomes (9, 34). Appropriate animal ethics committee approval is required. A generalised protocol is outlined in the following section but there can be considerable variation depending on the complexity of information sought, i.e., if the determination of distribution into tissues is required in addition to absorption into the circulation ... 

Trotta M, Peira E, Debernardi F, GaUarate M (2002) Elastic liposomes for skin delivery of dipotassiiun glycyrrhizinate. Int J Pharm 241(2) 319-327... 

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