Dr. Mohammad Javed Ansari, PhD. Contact info: javedpharma@gmail.com

COLLEGE OF PHARMACY

PHARMACEUTICS II

(PHT 312)

OBJECTIVES OF THE LECTURE

• At the end of this lecture, you will be aware of:

• What are liposomes?

• What are liposomes structure, Classification,

Preparation, Application advantages &

disadvantages?

• What are Nanoparticles?

• What are different types of Nanoparticles?

• How to preparation nanoparticles?

• What are Application advantages & disadvantages

of Nanoparticles?

• What are some marketed colloidal formulations?

What are Liposomes? • Derived from two Greek words: 'LIPO' meaning FAT and

'Soma' meaning BODY.

• Lipsomes are FAT BODIES / vesicular structures

consisting of hydrated bilalyers of phospholipids.

• Liposomes were discovered accidently by British

haematologist Dr. Alec D Bangham in 1961, at the

Babraham Institute, in Cambridge.

• They were testing the institute's new electron microscope

by adding negative stain to DRY PHOSPHOLIPIDS,

observing CELL MEMBRANE LIKE STRUCTURE.

• Note: Phospholipids are a special group of lipids

containing phosphate which is hydrophilic or polar (able

to be mixed in water).

What are Liposomes?

• When phospholipids are immersed in water they arrange

themselves so that their hydrophilic regions point toward

the water and their hydrophobic regions point away from

the water and stick together in bilayer form.

What are Liposomes? • PHOSPHOLIPID BILAYERS are the core structure of

liposome and cell membrane formations.

`

Liposome

Cell Membrane

Hydrophilic heads

Lipophilic tails

Aq. cavity

TYPES OF LIPOSOMES Liposomes are classified based on their structure as:

Vesicle Types Abbr Diameter Size

Number of lipid bilayers

Small unilamellar vesicles

SUV Diameter of 20-100nm.

One lipid bilayer

Large unilamellar vesicles

LUV Diameter of 100nm.

One lipid bilayer

Oligolamellar vesicles

OLV Diameter of 0.1-1m.

Approximately five lipid bilayers

Multilamellar vesicles

MLV Diameter of 0.5m.

Five to twenty lipid bilayers

Multivesicular vesicles

MVV Diameter of 1m.

Multi-compartmental

structure

Conventional Long circulating

Immuno Cationic

1) Multi-lamelar vesicles(MLV): (a) Liquid hydration method:

• In this method a solution of lipid is taken and it is

evaporated which leaves a film in the vessel on complete

evaporation of the solvent .

• The film is hydrated and subjected to centrifugal force

which produce liposomes

This method is not so advantageous as it involves very

low loading of drug.

The drug content can be increased by the use of

immiscible solvent (petroleum ether or diethyl ether) to it.

(b) Solvent spherule method:

• This method produces liposomes of uniform size

distribution. It is achieved by the use of lipid dissolved

hydrophobic solvent dispersed in the aqueous solvent.

2) Small unilaminar vesicle:

(a) sonication method:

• Multi lamelar liposomes (MLV) are subjected to

sonication by bath type sonicator or probe type

sonicator.

o But the major drawback is that as we have selected

the MLV which posses very small internal volume

with in SMV so formed will also be having a small

internal diameter.

(b) French pressure cell method:

• MLV are allowed to pass through a small orifice at a

pressure of 20000 psi and a temperature of 400C.

there is a reduction in the outer layers during the

passage and would result in SULV.

·

3) Large unilaminar vesicles:

• It has a very high encapsulation efficiency.

(i) Solvent injection method:

(a) Ether infusion method: a lipid solution is prepared in

diethyl ether or ethanol/ ether and injected into the aqueous

solution of material to be incorporated under reduced

pressure at a temperature of 55 to 60oC.

(b) ethanol injection method: the ehanolic solution of lipid was

injected rapidly into excess of buffer solution. But so formed

liposomes will have a a wide range of heterogeneity of 30-110

nm.

(c) Detergent removal method: detergents are prepared at

their critical micelle concentration to solubilize the lipids.

Once the lipids are solubilized the detergent is evaporated by

dialysis or by gel chromatography or other methods.

Applications of liposomes

• Liposomes as drug delivery carrier

Liposomes can be loaded by pharmaceutical or other

ingredients by two principal ways:

1. Lipophilic substances can be associated with liposomal

membrane,

2. hydrophilic substances can be dissolved in the inner liquid

core of liposomes.

• Flexible Liposomes dosage forms: Liposomes can be

formulated as a suspension, as an aerosol, or in a semisolid

form such as gel, cream and lotion, as a dry vesicular powder

(pro-liposome) for reconstitution.

• Flexible Liposomes route of administration: Liposomes can

be administered through most routes of administration

including ocular, pulmonary, nasal, oral, intramuscular,

subcutaneous, topical and intravenous.

Applications of liposomes

• Liposomal protection of sensitive drugs

Liposomes form a barrier around their contents, which is resistant to

enzymes in the mouth and stomach, alkaline solutions, digestive

juices, bile salts, and intestinal flora that are generated in the human

body, as well as free radicals

The contents of the liposomes are, therefore, protected from oxidation

and degradation.

Liposomal solubilisation of insoluble drugs

Improve solublization and bioavalability of hydrophobic drugs such as

Amphotericin, cyclosporin, minoxidil, paclitoxel etc.

• Liposomes as drug targeting carrier

Site specific delivery of anticancer drugs to tumor cells.

• Liposomes as macro/biomolucular delivery system

Macromolecules like superoxide dismutase, haemoglobin,

erythropoietin, interleukin-2 and interferon-g.

• Liposomes are biocompatible, completely biodegradable,

non-toxic, flexible and non-immunogenic for systemic and

non-systemic administrations.

• Improved solubility of insoluble /hydrophobic drugs.

• Improved Stability of drugs (Protects sensitive drug).

• Improved PK (Changes the absorbance and

biodistribution).

• Increased efficacy and therapeutic index.

• Reduced toxicity and side effects.

• Site specific delivery (Directly to site).

• Controlled drug release: Prolong time -increase duration of

action and decrease administration.

• Altered liposome surface with ligand (antibodies,

enzymes, protein A, sugars).

• The main disadvantage of the standard liposome

formulations:

• their rapid clearance from circulation due to uptake, by the

reticuloendothelial system(RES), primarily in the liver.

• Short half-life.

• Fewer stability

• Low solubility.

• Low encapsulation efficiency

• Leakage and fusion of encapsulated drug / molecules.

• Production cost is high.

• Nanoparticles (NP) are solid colloidal particles ranging in size

from 10 nm to 1000nm.

• NP consist of macromolecular materials in which the active

principle /drugs are dissolved, entrapped or encapsulated,

and/or to which the active principle is absorbed or attached.

• Based on the arrangement of drug and polymer matrix,

nanoparticles can be classified into two types: nanospheres

and nanocapsules.

• In nanospheres, drugs are either adsorbed or entrapped inside

the polymeric matrix. In nanocapsules, drugs are confined to

the inner liquid core while the external surface of nanoparticles

is covered by the polymeric membrane.

• PNP for drug delivery are generally made up of biocompatible

and biodegradable polymers obtained from either natural or

synthetic source.

• Natural polymers include chitosan, albumin, rosin, sodium

alginate and gelatin.

• Synthetic polymers include poly (lactic acid) PLA, poly (D,L-

glycolide), poly (lactide-co-glycolide), poly (caprolactones)

(PCL) and poly (cyanoacrylates).

• The kinetics of drug release from nanoparticles depends on the

strength of hydrophobic interactions between the polymer and

drug and polymer degradation rate.

• The uptake and distribution of nanoparticles depend on its size.

Nanoparticles of size ~10 nm are utilized for extended

circulation, while ~100 and ~200 nm particles are utilized for

passive targeting and intracellular drug delivery respectively.

• Natural or synthetic polymer

• Inexpensive

• Nontoxic

• Biodegradable

• Nonthrombogenic & Nonimmunogenic

• Particle diameter <100nm

• No platelet aggregation

• Noninflammatory

• Prolonged circulation time

• SLN have been developed as alternative delivery system

to conventional polymeric nanoparticles.

• SLN are composed of physiological lipid, dispersed in

water or in an aqueous surfactant solution.

• SLNs combine advantages of polymeric nanoparticles, fat

emulsions and liposomes, but avoid some of their

disadvantages.

• They are biodegradable, biocompatible and non-toxic.

• Advantages: Avoidance of coalescence leads to enhanced

physical stability.

• Reduced mobility of incorporated drug molecules leads to

reduction of drug leakage.

• Static interface solid/liquid facilitates surface modification

Nanoparticles can be produced by either

Dispersion-based processes (which involves breaking

larger micrometer-sized particles into nanoparticles) or

precipitation-based processes /condensation.

Dispersion-based processes

a) Wet milling : Wet milling is an attrition-based process in

which the drug is dispersed first in an aqueous-based

surfactant solution. The resulting suspension is subjected to

wet milling using a pearl mill in the presence of milling

media.

b) Probe sonication

High-pressure homogenization is based on the principle of

cavitation (i.e., the formation, growth, and implosive collapse

of vapor bubbles in a liquid.

c) High-pressure Homogenization

In this process, a drug presuspension is subjected to

homogenization at high pressure (50-100 Mpa).

PREPARATION OF NANOPARTICLES

Precipitation-based processes

a) Emulsification Technology

Drug solution in an organic solvent is dispersed in the

aqueous phase containing surfactant to prepare emulsion.

Evaporation of organic solvent under reduced pressure,

results in the precipitation of drug particles to form a

nanoparticle suspension which is stabilized by the added

surfactant.

b) Spray freezing into liquid (SFL):

Drug solution is atomized into a cryogenic liquid such as

liquid nitrogen to produce frozen nanoparticles which are

subsequently lyophilized to obtain free flowing powder.

c) Evaporative precipitation into aqueous solution (EPAS).

Drug solution in a low boiling organic solvent is heated under

pressure to a temperature above the solvent's normal boiling

point and then atomized into a heated aqueous solution

containing stabilizing surfactant.

PREPARATION OF NANOPARTICLES

• Increased active agent surface area results in a faster

dissolution of the active agent in an aqueous environment,

such as the human body.

• Faster dissolution generally equates with greater

bioavailability, smaller drug doses, less toxicity.

• Decreased toxicity.

• Longer shelf-stability

• High carrier capacity

• Ability to incorporate hydrophilic and hydrophobic drug

• Can be administered via different routes

• Longer clearance time

• Ability to sustain the release of drug

• Targeted delivery of drugs at cellular and nuclear level.

• Involves higher manufacturing costs which may in turn

lead to increase in the cost of formulation.

• Involves use of harsh toxic solvents in the preparation

process.

• May trigger immune response and allergic reactions.

• Extensive use of poly(vinyl alcohol) as stabilizer may have

toxicity issues

Doxil® Doxorubicin

hydrochloride encapsulated in Stealth

® liposomes (100

nm)

FDA 1995 AIDS-related KS, multiple myeloma, ovarian cancer

DaunoXome® Daunorubicin citrate

encapsulated in liposomes (45 nm)

FDA 1996 HIV-related KS

AmBisome® Amphotericin B

encapsulated in liposomes (60–70 nm)

FDA 1997 Systemic fungal infections

DepoCyt® Cytarabine encapsulated

in multivesicular liposomes

FDA 1999/2007 Lymphomatous malignant meningitis

Inflexal®

V Influenza virus antigens (hemagglutinin, neuraminidase) on surface of 150 nm Liposomes

Switzerland 1997 Influenza vaccine

Marqibo

®

Vincristine sulfate encapsulated in sphingomyelin/cholesterol (60/40, molar) 100 nm liposomes

FDA 2012 Acute lymphoid leukemia,

Abraxane

®

Nanoparticles (130 nm) formed by albumin with conjugated paclitaxel44,45

FDA 2005 Metastatic breast cancer, non-small-cell lung cancer (IV)

Opaxio® Paclitaxel covalently linked to solid

nanoparticles composed of polyglutamate

FDA 2012 Glioblastoma

Rapamune® Rapamycin (sirolimus) as

nanocrystals formulated in tablets FDA 2002 Immunosuppressant (oral)

Emend® Aprepitant as nanocrystal FDA 2003

Emesis, antiemetic (oral)

Tricor®

Triglide®

Fenofibrate as nanocrystals FDA 2004

Megace ES® Megestrol acetate as nanocrystal FDA 2005

Anorexia, cachexia

Opaxio® Paclitaxel covalently linked to solid

nanoparticles composed of polyglutamate

FDA 2012 Glioblastoma

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4172146/table/t1-ijn-9-4357/ http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4172146/ http://www.drug-dev.com/Main/Back-Issues/NANOTECHNOLOGY-MARKET-Nanotechnology-Markets-in-He-803.aspx http://jocpr.com/vol7-iss6-2015/JCPR-2015-7-6-257-264.pdf

GOOD LUCK ..