KATARINA BAUEROVA

Department of Galenic Pharmacy

Faculty of Pharmacy, Comenius UniversityBratislava, March 2020

Liposome was found by Alec Bangham from Babraham

Institute in Cambridge, England in 1965.

In 1990, Amphotericin B in liposomes were approved in

Ireland.

In 1995 F.D.A approved liposomal Doxorubicin.

Liposome is a lipid vesicle suspending in the hydro-phase

with a diameter of 0.0025~3.5um.

The membrane of liposome is made of phospholipids, which

have phosphoric acid sides to form the liposome bilayers.

When phospholipids are dispersed in water they

spontaneously form closed structure with

internal aqueous compartments bounded by

phospholipid bilayer membranes, these are

called liposomes.

Hydrophilic (AQUEOUS CAVITY)

Hydrophobic(PHOSPHOLIPID BILAYER)

PHOSPHOLIPIDS: They are the major structural

components of biological membranes.

CHOLESTEROLS: It form bilayer structure by

incorporating into phospholipid membrane in very

high concentration up to 1:1 or 2:1. It acts as

“fluidity buffer”

Biocompatible, completely biodegradable, non-toxic, flexible,

no immunogenic.

Liposomes supply both a lipophilic environment and aqueous

“milieu interne” in one system. Can protect encapsulated

drug.

Reduce exposure of sensitive tissues to toxic drugs.

Alter the pharmacokinetic and pharmacodynamic property of

drugs (reduced elimination, increased circulation life time).

Flexibility to couple with site-specific ligands to achieve active

targeting (anticancer and antimicrobial drugs).

Liposomes can encapsulate both micro and macromolecules

such as haemoglobin, erythropoeitin, interferon gamma etc.

Can be formulated into multiple dosage forms.

Production cost is high.

Leakage and fusion of encapsulated

drug molecules.

Sometimes phospholipid undergoes

oxidation and hydrolysis like reaction.

Short half-life.

Low solubility.

Size & its distribution

Surface charge

Entrapped volume

Lamellarity

Phase behaviour of liposomes

Drug release

Several techniques are available for assessing

liposome size and size distribution.

These include: static and dynamic light

scattering, and several types of microscopy

techniques, size-exclusion chromatography (SEC),

field-flow fractionation and analytical centrifugation.

A method using free flow electrophoresis is used

to determine the surface charge

Liposome lamellarity determination is often

accomplished by 31P NMR

The entrapped volume can often be deduced from

measurements of the total quantity of solute

entrapped inside liposome assuring that the

concentration of solute in the aqueous medium

inside liposomes is the same as that in the

solution used to start with, & assuming that no

solute has leaked out of the liposomes after

separation from un-entrapped material.

An important behavior of lipid membran is the

existence of a temperature dependent, reversible

phase transition, where the hydrocarbon chains of

the phospholipid undergo a transformation from an

ordered (gel) state to a more disordered fluid

(liquid crystalline)

These changes have been documented by freeze

fracture electron microscopy, and demonstrated

by differential scanning calorimetry.

The mechanism of drug release from the liposome

can be assesed by the use of a well calibrated

in vitro diffusion cell.

The liposome based formulations can be assisted

by employing in vitro assays to predict

pharmacokonetics & bioavailability of the drug

before employing costly & time consuming in vivo

studies.

1. Phospholipid concentration/ Barlett assay, Stewartassay, HPLC.

2. Cholesterol concentration/ Cholesterol oxidase assay and HPLC.

3. Phospholipid peroxidation/ UV absorbance, iodometric analysis and GLC.

4. Phospholipid hydrolysis, cholesterol auto-oxidation/HPLC and TLC.

5. Osmolarity/ Osmometer.

CHOLESTEROL LECITHIN CHARGE

Dissolve in organic solvent

Remove lipid from organic solvent (vacuum )

Dispersion of lipid in aqueous media (hydration)

Purification of liposomes

Analysis of final product

Lipids film hydration by HAND SHAKING, NON HAND

SHAKING and FREEZE DRYING

Micro-emulsification

Sonication

French ppressure cell

Membrane extrusion

Dried reconstituted vesicles

Freeze-thawed liposomes

Ethanol injection

Ether injection

Double emulsion vesicles

Reverse phase evaporation vesicles

Stable pluri-lamellar vesicles

Detergent (cholate, alkyl glycoside, triton X-100)

removal from mixed micelles by:

Dialysis column chromatography

Dilution

Reconstituted Sendai virus enveloped

vesicles

21

Anticancer

Drugs

Antibacterial

Antiviral

DNA material

Enzymes

Radionuclide

Fungicides

Vaccines Malaria merozoite, Malaria sporozoite

Hepatitis B antigen, Rabies virus

glycoprotein

Amphotericin B

Hexosaminidase A

Glucocerebrosidase,

Peroxidase

Daunorubicin, Doxorubicin, Epirubicin

Methotrexate, Cisplatin, Cytarabin

Triclosan, Clindamycin hydrochloride,

Ampicillin, Peperacillin, Rifamicin

canal - CFTR

Applications of liposomes in pharmacology and

medicine can be divided into :

Therapeutic

Diagnostic

Enhanced solubility of amphiphilic and lipophilic

drugs

Inactive objective to the cells of the immune

system

Maintained free system of systemically or locally

administered liposomes

Site-avoidance mechanism

Precise targeting of location

Improved transfer of hydrophilic, electric molecules

such as antibiotics, chelators, plasmids and genes,

into cells.

Improved penetration into tissues, particularly in the

case of dermally functional liposomal dosage forms

These formulations mostly use the ionophore

Amphotericin B

Can be implemented in antibacterial and antiviral

therapy

Many different liposome formulations of various anticancer agents were shown to be less toxic than the free drug

This includes both short term and chronic toxicities because liposome encapsulation reduces the distribution of the drug molecules

The loading of these drugs into liposomes resulted in: increased flow life span improved deposition in the infected tissues defence from the drug metabolic deprivation altered tissue release of the drug improved uptake in organs decreased uptake in the kidney, myocardium, brain

Liposomal aerosol has several advantages over ordinary aerosol:

Sustained release

Prevention of local irritation

Reduced toxicity

Improved stability in the large aqueous core

Oral delivery of liposomes has a long history and

can be traced to early 1970s.

It is interesting to see that the initial application of

oral liposomes was with the delivery of insulin,

emphasizing the continual challenge in the field of

oral drug delivery

Instability

Poor permeability

Formulation challenges

Several mechanisms are proposed as follows:

Enhanced gastrointestinal stability

Mucoadhesion

Facilitated translocation across the mucus layers

Enhanced permeation across the enteric epithelia

Ligand-mediated endocytosis

Uptake by M cells

The first liposomal cosmetic product

Anti-aging cream by Christian Dior in 1986, which

has been followed by many other products

Enhance the penetration, solubility or stability,

cause longevity of effect.

Targeting the ingredient to desired site of action.

Reduce toxicity.

Increase control over pharmacokinetics and

pharmacodynamics, and make the product cost

effective.

Transferosomes

Niosomes

Novasomes

Marinosomes

Ultrasomes

Photosomes

Ethosomes

……

katarina.bauerova@savba.sk