Drug delivery applications liposomes

Fenske DB, Maurer N, Cullis PR. Encapsulation of weakly-basic drugs, anti-sense oligonucleotides and plasmid DNA within large unilamellar vesicles for drug delivery applications. In Torchilin VP, Weissig V, eds. Liposomes A Practical Approach. 2nd ed. Oxford Oxford University Press, 2002, Chapter 6. 

Vermette P, Meagher L, Gagnon E et al (2002) Immobilized liposome layers for drug delivery applications inhibition of angiogenesis. J Control Release 80 179-195... 

Among the several drug delivery systems, liposomes - phospholipid nanosized vesicles with a bilayered membrane structure - have drawn a lot of interest as advanced and versatile pharmaceutical carriers for both low and high molecular weight pharmaceuticals. At present, liposomal formulations span multiple areas, from clinical application of the liposomal drugs to the development of various multifunctional liposomal systems to be used in therapy and diagnostics. This chapter provides a brief overview of various liposomal products currently under development at experimental and preclinical level. 

RESS is useful for materials that are soluble in CO2. Unfortunately, CO2, with no dipole moment and very low polarizability, is a very weak solvent and dissolves very few polymers. Cosolvents such as methanol or acetone can be mixed with SCFs to increase the solvating power of SCFs during RESS. In drug delivery applications, RESS has been used to prepare polymeric films, microparticles, nanospheres, liposomes, and porous foams (Figure 1). A... 

Vermette, R Meagher, L. Gagnon, E. Griesser, H.J. Doillon, C.J. Immobilized liposomes layers for drug delivery applications Inhibition of angiogenesis. J. Contr. Release 2002,80 (1-3), 179-185. 

Although vesicles that occur in nature and in drug delivery applications are much smaller, GUV can give valuable data on the behavior of SUV because most observations are universal and scale invariant (i.e. permeability coefficients, first-order elastic constants, etc. are liposome size independent) or can be scaled down to smaller dimensions (entrapped volume, encapsulation efficiency, surface area). For many applications, however, the large size is preferred due to easier observation. 

Because of their ability to carry a wide variety of pharmaceuticals, liposomes have been studied for many different therapeutic situations, Therefore, the literature on this topic is abundant. Excellent reviews are available (e.g., Poznansky and Juliano, 1984 Gregoriadis, 1984, 1988b). We will restrict ourselves to the description of certain applications which illustrate the potential benefits of the use of liposomes in the field of drug delivery. 

A variety of other clinically important infections, such as brucellosis, listeriosis, salmonellosis, and various Mycobacterium infections, are of interest as these are often localized in organs rich in MPS cells. Liposome encapsulation has been demonstrated to improve therapeutic indices of several drugs in a number of infectious models. The natural avidity of macrophages for liposomes can also be exploited in the application of the vesicles as carriers of immunomodulators to activate these cells to an microbicidal, antiviral, or tumoricidal state. These studies were recently reviewed by Emmen and Storm (1987), Popescu et al. (1987), and Alving (1988). In addition to the treatment of "old" infectious diseases, the concept of MPS-directed drug delivery is of considerable interest for the therapy AIDS, possibly enabling control of human immunodeficiency virus replication in human macrophages. 

Besides drug delivery, liposomes have also gained wide acceptance in other fields such as diagnostic imaging (4,5) and vaccines. In this chapter we will focus our attention specifically on the conjugation of peptides to liposomes. We will outline the major techniques involved, present some applications of liposomes-peptides constructs, and mainly discuss their use as vaccines. 

Litzinger DC, Huang L. Phosphatidylethanolamine liposomes drug delivery, gene transfer and immunodiagnostic applications. Biochim Biophys Acta 1992 1113(2) 201-227. 

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