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Liposomes

  1. Gregory Gregoriadis1,
  2. Yvonne Perrie2

Published Online: 15 JAN 2010

DOI: 10.1002/9780470015902.a0002656.pub2

eLS

eLS

How to Cite

Gregoriadis, G. and Perrie, Y. 2010. Liposomes. eLS. .

Author Information

  1. 1

    London Bioscience Innovation Centre, Lipoxen plc, London, UK

  2. 2

    Aston University, Aston Pharmacy School, School of Life and Health Sciences, Birmingham, UK

Publication History

  1. Published Online: 15 JAN 2010
Table 1. Examples of the key characteristics of commonly used lipids
NameStructureTransition temperature (°C)Application
  1. Note: NA, not applicable.

Source: All structures taken from www.avantilipids.com.
Egg phosphatidylcholine (egg PC)inline imageBelow room temperaturePC (also known as lethicin) from natural sources is actually a mixture of phosphatidylcholines, with chains of different lengths and varying degrees of unsaturation. Commonly used as the main lipid in liposome formulations
1,2-distearoyl-phosphatidylcholine (18:0 PC or DSPC)inline image55A high transition temperature PC which can enhance stability of liposomes both on storage and in the circulation
Cholesterolinline imageNAThis inclusion of cholesterol within liposomal bilayers has been shown to result in an increased packing densities of phospholipids molecules which is thought to result from the accommodation of cholesterol in the molecular cavities formed by surfactant monomers assembled into vesicles. This space-filling action combined with the ability of cholesterol to complex with phospholipids can reduce bilayer permeability to small hydrophilic solutes and ions
1,2-dioleoyl-phosphatidylethanolamineinline image−16Fusogenic helper lipid, which enhances membrane fusion and destabilization, thus facilitating the disruption of endosomes and the release of the incorporated material into the cytoplasm of the cell. High levels of transfection efficiency when in combination with a cationic lipid
1,2-dioeoyl-3-trimethylammonium propane (DOTAP)inline image<0Monovalent cationic lipid consisting of a quarternary amine head group linked by ester groups to two unsaturated hydrocarbon chains
Dimethyldioctadecylammonium bromide (DDA or DDAB)inline image47A monovalent synthetic cationic lipid with adjuvant properties
1,2-distearoyl-phosphatidylglycerol (DSPG)inline image55An anionic lipid which can be used in liposomes to reduce fusion and enhance stability
Table 2. Effect of drug characteristics on loading within liposomes
Hydrophilic drugs (log P<1.7)Drugs with intermediate log P values (log P 1.7–5)Lipophilic drugs (log P>5):
Entrapped and retained in the aqueous core of liposomesSuch drugs can partition between the bilayer and aqueous phase resulting in low drug incorporation and retention within the liposomesIncorporated and retained within the liposome bilayers
Table 3. Examples of commercially available liposomes
Trade nameDrugDescriptionIndications
Caelyx/DoxilDoxorubicin80–100 nm sterically stabilized liposomes composed of pegylated distearoyl phosphatidylethanolamine, hydrogenated soy phosphatidylcholine and cholesterolAdvanced ovarian cancer
   Advanced breast cancer
   Aids-related Kaposi sarcoma.
DaunoXomeDaunorubicin∼45 nm liposomes composed of distearoyl phosphatidylcholine and cholesterolKaposi sarcoma
MyocetDoxorubicin150–190 nm size liposomes composed of egg phosphatidylcholine and cholesterolFirst-line treatment of metastatic breast cancer in women
DepocytCytarabineMultivesicular liposomes composed of dioleoylphosphatidylcholine (DOPC), cholesterol, triolein, and dipalmitoylphosphatidylglycerol (DPPG). The vesicles range in size from 3 to 30 micronsIntrathecal treatment of lymphomatous meningitis
AmBisomeAmphotericin BVesicles are <100 nm in size and composed of soy phosphatidylcholine, cholesterol, distearoylphosphatidylglycerolSystemic fungal infections
EpaxalFormalin inactivated hepatitis A virus150 nm virosomes composed of purified influenza virus surface antigens phosphatidycholine and phosphatidylethanolamineHepatitis A vaccine
Berna   
Inflexal V BernaPurified influenza haemagglutinin glycoprotein and neuraminidaseVirosome system similar to EpaxalInfluenza vaccine
VisudyneVereporfinVesicles composed of dimyristoyl phosphatidylcholine (DMPC) and egg phosphatidylglycerol (PG)Photodynamic therapy for macular degradation