Liposomes:
Formation, preparation,
properties and applications
Dr. S.S.Apte
Professor, Univ. College of Pharm. Sci., Kakatiya
University, Warangal
Presently:
NDDS Divn, Natco Research Centre
Hyderabad
Liposomal Anthracycline Antibiotics Used in
Therapy
Product
Drug
DaunoXome
Daunorubicin
citrate
Doxil
Doxorubicin
Caelix
Doxorubicin
Registration
Year
NeXstar
Pharmaceutical
Inc.
England
Sweden
USA
1995 r.
1995 r.
1996 r.
Sequus
Pharmaceutical
Inc.
USA
1995
Marketed By
Schering-Plough
Selected
European
Countries
1995 r.
Definition of Liposomes
Liposomes are spherical, self closed structures composed of curved lipid
bilayers which entrap part of the solvent, in which they freely float, into
their interior. They may consist of one or several concentric membranes;
their size ranges from 20 nm to several dozens µm, while thickness of the
membrane is around 4 nm.
Salient features
 Discovered in 1968 by Alec Bangham
 Delivery system for hydrophilic, lipophilic, and amphiphilic APIs
 Solubilization of lipophilic and amphiphilic APIs
 Protection of the API
 Reduction of side effects - toxicity of the active
 Sustained release
 Drug targeting
 Low application dose
Classification of Liposomes





SUV = Small Unilamellar Vesicles
LUV = Large Unilamellar Vesicles
MLV = Multilamellar Vesicles
LLC = Lamellar Liquid Crystalline Phase
MVV = Multivesicular vesicles
Liposomes are composed of one to several
hundreds concentric membranes
Vesicular delivery systems
liposomes (phospholipids + Cholesterol)
Vesicles
Niosomes (Nonionic surfactants +cholesterol)
Preparation of vesicles:
 Film casting via organic solvent
film hydration
ether-ethanol injection
 Reverse phase evaporation
 Through mixed micellar solution
 Mechanical methods
Characterization of vesicles:
Size and size distribution
- Dynamic light scattering
Electron microscopy
Coulter counter
Number of lamellae
- NMR spectroscopy
small angle X ray scatter
Charge
- Microelectrophoresis
Entrapment efficiency
- Gel filtration
Capture volume
- ultrafiltration
dialysis
protamine aggregation
ultracentrifugation
Release
- Dialysis
Liposomal Delivery of Anti-Cancer
Agents
 Slow Release: reduced peak levels of free drug and prolonged
tumor exposure
 Change in Biodistribution: avoiding drug deposition in certain
tissues will reduce tissue-specific toxicities
 Tumor Targeting: passive accumulation by enhanced
permeability and retention (EPR) effect
Phospholipids in topical pharmaceutical applications
Drug
Effects
Benzoyl peroxide
improved drug delivery; higher anti-bacterial
efficacy
better penetration; improved efficacy in pain
treatment
improved drug delivery; higher drug efficacy
improved penetration; higher drug efficacy
sustained release, drug efficacy improvement
enhanced penetration
enhanced penetration, rapid onset of action
controlled release, inhibition of absorption
improved drug delivery & efficacy
improved penetration and drug retention in
the skin
drug retention in the skin
controlled release
penetration enhancement
Flurbiprofen
Diclofenac
Heparin
Clindamycin phosphate
Aciclovir
Menthol & camphor
N,N-diethyl-meta-toluamide (DEET)
Povidone-Iodine
Tamoxifen
Econazol, Miconazol
Glycolic acid
Bethametasone 17-benzoate