This document provides an overview of liposomes, which are spherical vesicles composed of phospholipid bilayers that can encapsulate drugs for delivery. Key points include:
- Liposomes range in size from 25nm to 5000nm and consist of phospholipids, cholesterol, and an encapsulated drug molecule.
- They offer advantages for drug delivery such as ability to encapsulate both hydrophobic and hydrophilic drugs, increase drug stability, and provide controlled release.
- Common methods for preparing liposomes include lipid film hydration, mechanical dispersion techniques like sonication, and detergent removal methods.
- Liposomes have applications in cancer chemotherapy, oral drug delivery, topical applications, pulmonary delivery, and gene delivery due
Liposomes are defined as phospholipid vesicles consisting of one or more concentric lipid bilayers enclosing discrete aqueous spaces. The unique ability of liposomal systems to entrap both lipophilic and hydrophilic compounds enables a diverse range of drugs to be encapsulated by these vesicles.
Liposomes by Mr. Vishal Shelke
https://youtube.com/vishalshelke99
https://instagram.com/vishal_stagram
Liposomes
Sub :- Novel Drug Delievery Systems, Sterile Products Formulation & Technology
M.Pharm Sem II
Savitribai Phule Pune University
Introduction :-
Liposomes are vesicular structures composed of a lipid bilayer. These vesicular structures can be used as a vehicle for administration of nutrients and drugs.
Liposomes are concentric bilayered vesicles in which an aqueous volume is entirely enclosed by a membranous lipid bilayer.
Liposomes consist of Cholesterol, Phospholipid and drug molecule
Classification of Liposomes :-
Small Unilamellar (SUV) [20-100nm]
Medium Unilamellar (MUV)
Large Unilamellar (LUV) [>100nm]
Giant Unilamellar (GUV) [>1μm]
Multi Lamellar Vesicles (MLV) [0.5nm]
Oligolamellar Vesicles (OLV)
Multi Vesicular (MV) [>1μm]
ADVANTAGES
Provides selective passive targeting to tumor tissues.
Increased efficacy and therapeutic index.
Increased stability via encapsulation.
Reduction in toxicity of the encapsulated agents.
Improved pharmacokinetic effects (reduced elimination, increased circulation life times).
DISADVANTAGES
low solubility
short half life
high production cost
less stability
leakage and fusion of encapsulated drug
sometimes the phospholipid layer undergoes oxidation and hydrolysis reaction
Methods of Preparation of Liposomes
1 Mechanical Dispersion Method
Lipid film hydration by
hand shaken MLVs
Micro emulsification
Sonication
French pressure cell
Dried reconstituted vesicles
Membrane Extrusion Method
2 Solvent Dispersion Method
Ethanol injection
Ether injection
Double emulsion vesicles
Reverse phase
evaporation vesicles
3 Detergent Removal Method
Liposomes are defined as phospholipid vesicles consisting of one or more concentric lipid bilayers enclosing discrete aqueous spaces. The unique ability of liposomal systems to entrap both lipophilic and hydrophilic compounds enables a diverse range of drugs to be encapsulated by these vesicles.
Liposomes by Mr. Vishal Shelke
https://youtube.com/vishalshelke99
https://instagram.com/vishal_stagram
Liposomes
Sub :- Novel Drug Delievery Systems, Sterile Products Formulation & Technology
M.Pharm Sem II
Savitribai Phule Pune University
Introduction :-
Liposomes are vesicular structures composed of a lipid bilayer. These vesicular structures can be used as a vehicle for administration of nutrients and drugs.
Liposomes are concentric bilayered vesicles in which an aqueous volume is entirely enclosed by a membranous lipid bilayer.
Liposomes consist of Cholesterol, Phospholipid and drug molecule
Classification of Liposomes :-
Small Unilamellar (SUV) [20-100nm]
Medium Unilamellar (MUV)
Large Unilamellar (LUV) [>100nm]
Giant Unilamellar (GUV) [>1μm]
Multi Lamellar Vesicles (MLV) [0.5nm]
Oligolamellar Vesicles (OLV)
Multi Vesicular (MV) [>1μm]
ADVANTAGES
Provides selective passive targeting to tumor tissues.
Increased efficacy and therapeutic index.
Increased stability via encapsulation.
Reduction in toxicity of the encapsulated agents.
Improved pharmacokinetic effects (reduced elimination, increased circulation life times).
DISADVANTAGES
low solubility
short half life
high production cost
less stability
leakage and fusion of encapsulated drug
sometimes the phospholipid layer undergoes oxidation and hydrolysis reaction
Methods of Preparation of Liposomes
1 Mechanical Dispersion Method
Lipid film hydration by
hand shaken MLVs
Micro emulsification
Sonication
French pressure cell
Dried reconstituted vesicles
Membrane Extrusion Method
2 Solvent Dispersion Method
Ethanol injection
Ether injection
Double emulsion vesicles
Reverse phase
evaporation vesicles
3 Detergent Removal Method
liposomes are novel drug delivery dosage systems, where the drug is entrapped in phospholipid bilayered vesicles. the release of drug from the vesicles can be controlled or sustained.
the follwing presentation contain structure, classification and preparation methods, characterization and applications of liposomes.
liposomes are novel drug delivery dosage systems, where the drug is entrapped in phospholipid bilayered vesicles. the release of drug from the vesicles can be controlled or sustained.
the follwing presentation contain structure, classification and preparation methods, characterization and applications of liposomes.
Liposomes-Classification, methods of preparation and application Vijay Hemmadi
liposome preparation and application
A liposome is a tiny bubble (vesicle), made out of the same material as a cell membrane. Liposomes can be filled with drugs, and used to deliver drugs for cancer and other diseases. Membranes are usually made of phospholipids, which are molecules that have a head group and a tail group
Liposomes, Structure of liposome, phospholipids, classification of liposomes, method of preparation of liposomes, mechanism of liposome formation, application of liposomes.
liposomes used in preparation of both hydrophilic and hudrophobic drug.
it increases therapeutic efficiency by site targeting and increase circulatory time.
Vesicles are colloidal particles in which a concentric bilayer made-up of amphiphilic molecules surrounds an aqueous compartment Useful vehicle for drug delivery of both hydrophobic drugs and hydrophilic drugs, which are encapsulated in the interior aqueous compartment.
Pharmacopoeia is an official publication describing drugs, chemicals, and medicinal preparations as well as containing directions of compound identification. The word ‘Pharmacopoeia’ is widely used and common spelling but ‘Pharmacopeia’ used only in USP.
These lecture slides, by Dr Sidra Arshad, offer a quick overview of physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar leads (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
Factory Supply Best Quality Pmk Oil CAS 28578–16–7 PMK Powder in Stockrebeccabio
Factory Supply Best Quality Pmk Oil CAS 28578–16–7 PMK Powder in Stock
Telegram: bmksupplier
signal: +85264872720
threema: TUD4A6YC
You can contact me on Telegram or Threema
Communicate promptly and reply
Free of customs clearance, Double Clearance 100% pass delivery to USA, Canada, Spain, Germany, Netherland, Poland, Italy, Sweden, UK, Czech Republic, Australia, Mexico, Russia, Ukraine, Kazakhstan.Door to door service
Hot Selling Organic intermediates
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Ve...kevinkariuki227
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
Flu Vaccine Alert in Bangalore Karnatakaaddon Scans
As flu season approaches, health officials in Bangalore, Karnataka, are urging residents to get their flu vaccinations. The seasonal flu, while common, can lead to severe health complications, particularly for vulnerable populations such as young children, the elderly, and those with underlying health conditions.
Dr. Vidisha Kumari, a leading epidemiologist in Bangalore, emphasizes the importance of getting vaccinated. "The flu vaccine is our best defense against the influenza virus. It not only protects individuals but also helps prevent the spread of the virus in our communities," he says.
This year, the flu season is expected to coincide with a potential increase in other respiratory illnesses. The Karnataka Health Department has launched an awareness campaign highlighting the significance of flu vaccinations. They have set up multiple vaccination centers across Bangalore, making it convenient for residents to receive their shots.
To encourage widespread vaccination, the government is also collaborating with local schools, workplaces, and community centers to facilitate vaccination drives. Special attention is being given to ensuring that the vaccine is accessible to all, including marginalized communities who may have limited access to healthcare.
Residents are reminded that the flu vaccine is safe and effective. Common side effects are mild and may include soreness at the injection site, mild fever, or muscle aches. These side effects are generally short-lived and far less severe than the flu itself.
Healthcare providers are also stressing the importance of continuing COVID-19 precautions. Wearing masks, practicing good hand hygiene, and maintaining social distancing are still crucial, especially in crowded places.
Protect yourself and your loved ones by getting vaccinated. Together, we can help keep Bangalore healthy and safe this flu season. For more information on vaccination centers and schedules, residents can visit the Karnataka Health Department’s official website or follow their social media pages.
Stay informed, stay safe, and get your flu shot today!
Couples presenting to the infertility clinic- Do they really have infertility...Sujoy Dasgupta
Dr Sujoy Dasgupta presented the study on "Couples presenting to the infertility clinic- Do they really have infertility? – The unexplored stories of non-consummation" in the 13th Congress of the Asia Pacific Initiative on Reproduction (ASPIRE 2024) at Manila on 24 May, 2024.
HOT NEW PRODUCT! BIG SALES FAST SHIPPING NOW FROM CHINA!! EU KU DB BK substit...GL Anaacs
Contact us if you are interested:
Email / Skype : kefaya1771@gmail.com
Threema: PXHY5PDH
New BATCH Ku !!! MUCH IN DEMAND FAST SALE EVERY BATCH HAPPY GOOD EFFECT BIG BATCH !
Contact me on Threema or skype to start big business!!
Hot-sale products:
NEW HOT EUTYLONE WHITE CRYSTAL!!
5cl-adba precursor (semi finished )
5cl-adba raw materials
ADBB precursor (semi finished )
ADBB raw materials
APVP powder
5fadb/4f-adb
Jwh018 / Jwh210
Eutylone crystal
Protonitazene (hydrochloride) CAS: 119276-01-6
Flubrotizolam CAS: 57801-95-3
Metonitazene CAS: 14680-51-4
Payment terms: Western Union,MoneyGram,Bitcoin or USDT.
Deliver Time: Usually 7-15days
Shipping method: FedEx, TNT, DHL,UPS etc.Our deliveries are 100% safe, fast, reliable and discreet.
Samples will be sent for your evaluation!If you are interested in, please contact me, let's talk details.
We specializes in exporting high quality Research chemical, medical intermediate, Pharmaceutical chemicals and so on. Products are exported to USA, Canada, France, Korea, Japan,Russia, Southeast Asia and other countries.
Ozempic: Preoperative Management of Patients on GLP-1 Receptor Agonists Saeid Safari
Preoperative Management of Patients on GLP-1 Receptor Agonists like Ozempic and Semiglutide
ASA GUIDELINE
NYSORA Guideline
2 Case Reports of Gastric Ultrasound
Report Back from SGO 2024: What’s the Latest in Cervical Cancer?bkling
Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
MANAGEMENT OF ATRIOVENTRICULAR CONDUCTION BLOCK.pdfJim Jacob Roy
Cardiac conduction defects can occur due to various causes.
Atrioventricular conduction blocks ( AV blocks ) are classified into 3 types.
This document describes the acute management of AV block.
MANAGEMENT OF ATRIOVENTRICULAR CONDUCTION BLOCK.pdf
Liposomes
1. Liposomes- A Novel Drug Delivery System
By Tushar Chavan
M Pharmacy 2018-2019
K.Y.D.S.C.T.College of Pharmacy, Sakegaon
NMU, Jalgaon [MH]
Email: tusharchavantsc@gmail.com
Updated May 21, 2019
1. What are Liposomes
• Liposomes are concentric bilayered vesicles in which an aqueous core is entirely
enclosed by a membranous lipid bilayer mainly composed of natural or synthetic
phospholipids.
• Size range: 25nm-5000nm
• Liposomes consist of Cholesterol, Phospholipid and drug molecule.
2. A simple view of liposomes
“Liposomes are microscopic spheres made from fatty materials, predominantly
phospholipids. “Made up of one or more concentric lipid bilayers, and range in size from
50 nanometers to several micrometers in diameter
3. Advantages with liposomes
Suitable for delivery of hydrophobic, hydrophilic and amphipatic drugs and agents
Liposomes increases efficacy and therapeutic index of drug (actinomycin-D)
Liposome increased stability via encapsulation
Suitable for controlled release
Suitable to give localized action in particular tissues.
Suitable to administer via various routes
Liposomes help reduce the exposure of sensitive 4 tissues to toxic drugs
4. Disadvantages of liposomes
Production cost is high.
Leakage and fusion of encapsulated drug / molecules.
Sometimes phospholipid undergoes oxidation and hydrolysis like reaction.
Short half-life.
Low solubility.
5. Components of liposomes
The structural components of liposomes include: A. Phospholipids B. cholesterol
A. PHOSPHOLIPID • Major component of biological cell membrane Phospholipid
Hydrophobic tail 2 fatty acid chain containing 10-20 carbon atoms 0-6 double bond in each
chain Hydrophillic head or polar head Phosphoric acid bound to water soluble molecule
2. Commonly used other Phospholipids Natural phospholipid
I. PC- phosphatidyl choline
II. PE- phosphatidyl ethanolamine
III. PS –phosphatidyl serine Synthetic phosholipid
IV. DOPC = Dioleoyl Phosphatidylcholine
V. DOPE = Dioleoyl phosphatidyl ethanolamine
VI. DSPC = Distearoyl phosphatidyl choline
VII. DSPE = Distearoyl phosphatidyl ethanolamine
VIII. DLPC = Dilauryl phosphatidyl choline
Phosphatidylcholine PC
• The most common phospholipid use is phosphatidylcholine PC
• Phosphatidylcholine is amphipathic molecule containing i. A hydrophillic polar head
group phosphocholine ii. A glycerol bridge iii. A pair of hydrophobic acyl hydrocarbon chain
B. Cholesterol:
• Incorporation of sterols in liposome bilayer can bring about major changes in the
preparation of these membranes.
• Cholesterol does not by itself form bilayer structure,but can be incorporated into
phospholipid membranes in very high concentration unto 1:1 or even 2:1 molar ratios of
PC.
• Cholesterol incorporation increases the separation between the cholin head groups and
eliminates the normal electrostatic and hydrogen-bonding interactions.
Role of cholesterol in bilayer formation:
I. Cholesterol act as fluidity buffer
II. After intercalation with phospholipid molecules alter the freedom of motion of
carbon molecules in the acyl Chain
III. Restricts the transformations of
IV. Trans to gauche Conformations.
V. Incorporated into phospholipid membrane upto 1:1 or 2:1 of cholesterol to PC.
6. Preparation of Liposomes • Mechanism of Vesicle Formation A. The budding theory B.
The bilayer phospholipids theory
A.The budding theory – Stress induced hydration of phospholipids – Organization in to
lamellar arrays – Results in to budding of lipid bilayer leading to downsizing SUV OLV 13
B.The bilayer phospholipids theory
• Liposomes are formed when thin lipid films are hydrated
•The hydrated lipid sheets detach during agitation and self-close to form large,
multilamellar vesicles (LMV)
3. 7. Modes of liposomes/cell interaction 1. Endocytosis 2. Adsorption 3.fusion 4. Lipid
transfer
8. Factors affecting release of drug
• Solvents
•pH
•Temperature
• Agitation
• Enzymes
• Cell culture
• Volume Drug release from liposomes
•the lipid bilayer of the liposome can fuse with other bilayers (e.g. cell membrane) thus
delivering the liposome contents.
9. CLASSIFICATION OF LIPOSOMES
Structure Method of preparation Composition and application Conventional liposome
Speciality liposome
18. 1. Classification of liposomes based on Structure Unilamellar (UV)-all size range Small
Unilamellar(SUV) [20-100nm] Medium Unilamellar (MUV) Large Unilamellar (LUV)
[>100nm] Giant Unilamellar (GUV) [>1μm] Multi Lamellar Vesicles (MLV) [0.5nm]
Oligolamellar Vesicles (OLV) Multi Vesicular (MV) [>1μm] 18
19. 2. Classification of liposomes Based on Method of Preparation Single or oligo lamellar
vesicle made by reverse phase evaporation method (REV’s) Multi lamellar vesicle made by
reverse phase evaporation method (MLV-REV Stable pluri lamellar vesicle (SPLV) Frozen
and thawed multi lamellar vesicle (FATMLV) Vesicle prepared by extrusion technique (VET)
Dehydration- Rehydration method (DRV) Dehydration- Rehydration method (DRV) 19
20. 3. Classification of liposomes Based on Composition and Application Type of liposome
Abbreviation Composition Conventional liposome CL Neutral of negatively charge
phospholipids and cholesterol Fusogenic liposome RSVE Reconstituted sendai virus
enveops pH sensitive liposomes - Phospholipids such as PER or DOPE Cationic liposome -
Cationic lipid with DOPE Long circulatory liposome LCL Neutral high temp, cholesterol and
5-10% PEG, DSP Immune liposome IL CL or LCL with attached monoclonal antibody or
recognition sequences 20
21. 4. Classification of Liposomes Based Upon Conventional Liposome 1). Stabilize natural
lecithin (PC) mixtures 2). Synthetic identical, chain phospholipids 3). Glycolipids containing
liposome 21
22. 5.)Classification of Liposomes based upon Speciality 5.) Liposomes Bipolar Fatty Acids
Antibody directed Liposome Methyl/Methylene x- linked liposome Lipoprotein coated
liposome Carbohydrate coated liposome Muiltiple Encapsulated Liposome 22
10. Methods of liposome preparation
1. Passive loading techniques
2. Active loading techniques
4. 3. Mechanical dispersion methods
4. Solvent dispersion methods
5. Detergent removal technique
LIPID FILM HYDRATION
BY HAND SHAKING,
FREEZE DRYING
NON HAND SHAKING
MICRO EMULSIFICATION
SONICATION
FRENCH PRESSURE CELL
MEMBRANE EXTRUSON
DRIED RECONSTITUTED VESICLES
ETHANOL INJECTION
ETHER INJECTION
DOUBLE EMULSION
REVERSE PHASE EVAPORATION
6. Detergent removal from mixed vesicles by
DIALYSIS
Column Chromatography
DILUTION
11. General Method Of Liposome Preparation
1 • Cholesterol + Lecithin + Charge and Dissolve in organic solvent
2 • Drying down lipid from organic solvent( Vaccum ) • Dispersion of lipid in aqueous
media (Hydration
3 • Purification of resultant Liposomes • Analysis of final product 24
25. 1. Mechanical dispersion method Lipid dissolve in organic solvent/co-solvent Remove
organic solvent under vacuum Film deposition Solid lipid mixture is hydrated by using
aqueous buffer Lipid spontaneously swell & Hydrate Liposome 25
26. 1) Lipid Hydration Method A.) By hand shaking method vesiculate to form Multi
lamellar vesicles(MLVs) Upon hydration lipids swell and peel out from RB flask Then film is
treated with aqueous medium Lipids form stacks of film from organic solution 26
27. 1) Lipid Hydration Method B.) NON-
from hand shaken method wherein it uses a stream of nitrogen to provide agitation rather
n
for 15-20 min Milky suspension centrifugation LUV 27
28. 1) Lipid Hydration Method C.) FREEZE DRYING • Another method of dispersing the lipid
in a finely divided form, prior to addition of aqueous media, is to freeze dry the lipid
dissolved in a suitable organic solvent. • The solvent choice depends on the freeze point
which needs to above the temperature of the condenser lyophilizers. Tertiary butanol is
5. considered to be most ideal solvent. • After obtaining the dry lipid which is an expanded
foam like structure, water or saline can be added with rapid mixing above the phase
transition temperature to give MLVs. 28
29. 2.) MICRO EMULSIFICATION • This method is provided for preparing small lipid vesicles
in commercial quantities by microemulsifying lipid compositions using very high shear
forces generated in a homogenizing apparatus operated at high pressures at a selected
temperature. • At least 20 circulations (approximately 10 minutes) but not greater than
200 circulations (100 minutes) are sufficient to produce a micro emulsion of small vesicles
suitable for biological application. 29
this method.
re of the lipid dispersion is
usually easier in this method, in contrast to sonication by dispersal directly using the tip.
30
31. 4.) FRENCH PRESSURE CELL • The method involves the extrusion of MLV at 20,000 psi
at 4°C through a small orifice. • The method has several advantages over sonication
method. • The method is simple rapid, reproducible and involves gentle handling of
unstable materials. • The resulting liposomes are somewhat larger than sonicated SUVs. •
The drawbacks of the method are that the temperature is difficult to achieve and the
working volumes are relatively small (about 50 mL maximum). 31
Vesicle contents are exchanged with dispersion medium during breaking and resealing of
entrapment, the water soluble compounds should be present in suspending medium
during the extrusion process. 32
33. 6.) DRIED RECONSTITUTED VESICLES SUV’s in SUV’s with DRV Freeze dried aqueous
solute to be membrane phase entrapped Solutes with oligo and uni lamellar Freeze
membranes drying Rehydration 33
34. B] Solvent dispersion methods • Ethanol injection –SUV • Ether injection -LUV •
Reverse phase evaporation vesicle –LUV • Double emulsion vesicles Stable plurilamellar
vesicles 34
35. 1.) Ethanol Injection Method • A lipid solution of ethanol is rapidly injected to a vast
excess of buffer. The MLVs are immediately formed. • The drawbacks of the method are
that the population is heterogeneous (30-110 nm), liposomes are very dilute, it is difficult
to remove all ethanol because it forms azeotrope with water and the possibility of various
biologically active macromolecules to inactivation in the presence of even low amounts of
ethanol. 35
36. 2.) Ether Infusion Method • A solution of lipids dissolved in diethyl ether or
ether/methanol mixture is slowly injected to an aqueous solution of the material to be
encapsulated at 55-65°C or under reduced pressure. • The subsequent removal of ether
6. under vacuum leads to the formation of liposomes. • This method is used to treat sensitive
lipids very gently. 36
37. Double emulsification • In this process, an active ingredient is first dissolved in an
aqueous phase (w1) which is then emulsified in an organic solvent of a polymer to make
a primary w1/o emulsion. • This primary emulsion is further mixed in an emulsifier-
containing aqueous solution (w2) to make a w1/o/w2 double emulsion. • The removal of
the solvent leaves microspheres in the aqueous continuous phase, making it possible to
collect them by filtering or centrifuging. 37
38. 3.) Reverse-phase evaporation Lipid organic solvent and aqueous solution are i. mixed,
ii. sonicated, iii. formation of w/o emulsion, iv. evaporate to remove the organic solvent
Lipids form a phospholipid bilayer on vigorous shaking , water droplets collapse and
formation of LUV’s takes place. 38
39. Reverse phase evaporation technique. Lipid in solvent solution Two-phase system
Water in oil emulsion Gel formation Solvent removal REV liposomes Conti… 39
40. C. Detergent removal method • The micellar dispersion is then subjected to one of the
following methods to remove the detergent: I. DIALYSIS :- Detergents with high CMC (10-
20 mM ) are used so that their removal is facilitated e.g. bile salts- sodium cholate and
sodium deoxycholate , or synthetic detergents like octileglucoside . II. COLUMN
CHROMATOGRAPHY :- By passing dispersion over a Sephadex G-25 column. 40
41. i.) Dialysis Method Dialysis is the simplest procedure used for the removal of the
unbound drug, except when macromolecular compounds are involved Advantages:
effective in removing nearly all of the free drug with a sufficient number of changes of the
dialyzing medium 41
42. ii.) Column Chromatography • Phospholipid in the form of either sonicated vesicle or
as a dry film, at a molar ratio of 2:1 with deoxycholate form unilamellar vesicles of 100nm
on removal of deoxycholate by column chromatography 42
43. B. Active loading technique AFTER DRYING IN PROCESS FILM/CAKE OF LIPID IS FROM
STACKS OF LIPID BILAYER FORM SWELLING IN FLUID SHEET IS SELF CLOSE LOADING OF
DRUG ON pH-
Two steps process generates this pH imbalance and active (remote) loading. 1) Vesicles
are prepared in low pH solution, thus generating low pH within the liposomal interiors 2)
amino groups are relatively lipophipic at high pH and hydrophilic at low pH. 43
44. 1.) Lyophilization • Freeze-drying (lyophilization) involves the removal of water from
products in the frozen state at extremely low pressures. • The process is generally used to
dry products and are thermo labile and would be destroyed by heat-drying. • The
technique has a great potential as a method to solve long term stability problems with
respect to liposomal stability. • It is exposed that leakage of entrapped materials may take
place during the process of freeze- drying and on reconstitution. 44
45. 2.) Pro-liposomes: lipid Dried over lipid Finely divided particulate support like
continuous hydration and lipid is dried over the finally divided particulate support i.e.-
NaCl, Sorbitol, or other polysaccharides. These dried lipid coated particulates are called as
7. support is rapidly dissolved and lipid film hydrate to form MLVs 45
12. Uses of liposomes
• Chelation therapy for treatment of heavy metal poisoning
• Enzyme replacement
• Diagnostic imaging of tumors
• Study of membranes
• In gene delivery.
• As drug delivery carriers.
• Enzyme replacement therapy.
• Liposomes in antiviral/anti microbial therapy.
• In multi drug resistance.
• In tumour therapy.
• In immunology.
• In cosmetology 46
13. Applications
• Liposomes are successfully used to entrap anticancer drugs. This increases circulation
life time, protects from metabolic degradation.
1.Cancer chemotherapy • Steroids used for arthritis can be incorporated into large MLVs.
• Alteration in blood glucose levels in diabetic animals was obtained by oral administration
of liposome encapsulated insulin
2.Liposomes as carrier of drug in oral treatment • Drugs like triamcilone, methotrexate,
benzocaine, corticosteroids etc can be successfully incorporated as topical liposome
3.Liposomes for topical applications
4. Liposomes for pulmonary delivery Inhalational devices like nebulizers are use to
produce an aerosol of droplets containing liposomes. 47
Especially good for in- -1000 times more plasmid DNA
needed for the same transfer efficiency as for viral vector 48
49. Lipofection 49
50. Liposomes could serve as tumor specific vehicles (even without special targeting)
Liposomes better penetrate into tissues with disrupted endothelial lining 50
14. Characterization of liposomes
• Shape, size and its distribution
• Surface charge
• Percentage drug entrapment
• Entrapped volume
• Lamellarity
• Phase behavior of liposome
8. • Percentage drug release
15. References
1) ‘Controlled and Novel Drug Delivery’, “JAIN N.K.’’, CBS Publisher And Distributors.Page
No.307-321.
2) ‘Targeted and controlled drug delivery, Novel carrier Systems’ , “VYAS S.P. and KHAR
R.K.’’, CBS Publishers Page no.181 -195.
3) A.Chonn,P.R.Cullis,“Recent advances in liposome technologies and their applications for
systemic gene delivery”,Advanced Drug Delivery Reviews
4) Liposomes preparation methods by Mohammad riaz ,Pakistan Journal of
Pharmaceutical Sciences Vol.19(1), January 1996, pp.65-77
5) Liposome- as drug carriers-International Journal of Pharmacy & life sciences- Himanshu
Anwekar*, Sitasharan Patel and A.K Singhai
6) http://www.avantilipids.com
7) http://www. Mssm.edu/medicine/thrombosis/phosphol.html
8) Garrett, R. and Grisham C. Biochemistry, 2nd ed. Saunders Colleges Publishing. New
York (1999). 264
9) "Liposomes." www.collabo.com/liposom0.htm
10) Sharma Vijay K1*, Liposomes: Present Prospective and Future
Challenges,International Journal Of Current Pharmaceutical Review And Research, oct
2010,vol1, issue 2,6-16
11) Himanshu Anwekar*, Liposome- as drug carriers, International Journal Of Pharmacy &
Life Sciences, Vol.2, Issue 7: July: 2011, 945-951 52
53. 53