site specific drug delivery system

DELIVERD BY-
RAJENDRA D. MAHAJAN
M. PHARM 1ST
RTMNU NAGPUR

CONTENTS :CONTENTS :
• INTRODUCTION
• TARGETED DRUG DELIVERY SYSTEM
• ACTIVE AND PASSIVE TARGETING
• RELEASED ERYTHROCYTES
• MONOCLONALANTIBODIES

INTRODUCTIONINTRODUCTION ::
‘Targeted drug delivery system is a special form of drug
delivery system where the medicament is selectively
targeted or delivered only to its site of action or
absorption and not to the non-target organs or tissues or
cells.’
• It is a method of delivering medication to a patient in a
manner that increases the concentration of the medication
in some parts of the body relative to others.
• Targeted drug delivery seeks to concentrate the medication
in the tissues of interest while reducing the relative
concentration of the medication in the remaining tissues.
• This improves efficacy and reduce side effects.

THE DRUG MAY BE DELIVEREDTHE DRUG MAY BE DELIVERED :
• To the capillary bed of the active sites.
• To the specific type of cell (or) even an intracellular
region. Ex: Tumour cells but not to normal cells.
• To a specific organ (or) tissues by complexion with the
carrier that recognizes the target.
OBJECTIVEOBJECTIVE :
• To achieve a desired pharmacological response at a
selected sites without undesirable interaction at other sites,
there by the drug have a specific action with minimum
side effects & better therapeutic index.
• Ex- In cancer chemotherapy and enzyme replacement
therapy.

REASON FOR DRUG TARGETINGREASON FOR DRUG TARGETING :
• In the treatment or prevention or diseases.
• Pharmaceutical drug instability in conventional dosage
form solubility ,biopharmaceutical low absorption, high-
membrane bounding, biological instability,
pharmacokinetic / pharmacodynamic short half life, large
volume of distribution, low specificity, clinical, low
therapeutic index.

IDEAL CHARACTERISTICSIDEAL CHARACTERISTICS :
• It should be nontoxic, biocompatible, biodegradable,
and physicochemical stable invivo and invitro.
• Restrict drug distribution to target cells or tissues or
organs and should have uniform capillary distribution.
• Controllable and predicate rate of drug release.
• Drug release does not effect the drug action.
• Therapeutic amount of drug release.
• Minimal drug leakage during transit.

ADVANTAGESADVANTAGES :
• Drug administration protocols may be simplified.
• Toxicity is reduced by delivering a drug to its target site,
there by reducing harmful systemic effects.
• Drug can be administered in a smaller dose to produce the
desire effect.
• Avoidance of hepatic first pass metabolism.
• Enhancement of the absorption of target molecules such as
peptides and particulates.
• Dose is less compared to conventional drug delivery
system.

DISADVANTAGESDISADVANTAGES :
• Rapid clearance of targeted systems.
• Immune reactions against intravenous administered carrier
systems.
• Insufficient localization of targeted systems into tumour
cells.
• Diffusion and redistribution of released drugs.
• Requires highly sophisticated technology for the
formulation.
• Requires skill for manufacturing storage, administration.
• Drug deposition at the target site may produce toxicity
symptoms.

CARRIER OR MARKERSCARRIER OR MARKERS :
• Targeted drug delivery can be achieved by using
carrier system.
• Carrier is one of the special molecule or system
essentially required for effective transportation of loaded
drug up to the pre selected sites.
• They are engineered vectors, which retain drug inside or
onto them either via encapsulation and/ or via spacer moiety
and transport or deliver it into vicinity of target cell.
Pharmaceutical carriers :
 Polymers
 Microcapsules
 Microparticles
 Lipoproteins
 Liposomes
 Micelles

STRATEGIES OF DRUG TARGETINGSTRATEGIES OF DRUG TARGETING
1) Passive Targeting :
• Drug delivery systems which are targeted to
systemic circulation are characterized as Passive
delivery systems.
• In this technique drug targeting occurs because of the
body’s natural response to physicochemical
characteristics of the drug or drug carrier system.

2) Inverse Targeting :
• In this type of targeting attempts are made to avoid
passive uptake of colloidal carrier by RES (Reticulo
Endothelial Systems) and hence the process is
referred to as inverse targeting.
• To achieve inverse targeting, RES normal function is
suppressed by pre injecting large amount of blank
colloidal carriers or macromolecules like dextran
sulphate
• This approach leads to saturation of RES and
suppression of defence mechanism. This type of targeting
is a effective approach to target drug(s) to non-RES
organs.

3) Active Targeting :
• In this approach carrier system bearing drug
reaches to specific site on the basis of
modification made on its surface rather than
natural uptake by RES.
• Surface modification technique include coating of
surface with either a bioadhesive, nonionic
surfactant or specific cell or tissue antibodies (i.e.
monoclonal antibodies) or by albumin protein.
3 Types
o First order targeting (organ compartmentalization).
o Second order targeting (cellular targeting).
o Third order targeting (intracellular targeting).

4) Ligand Mediated Targeting : Achieved using
specific mechanisms such as receptor dependent uptake of
natural LDL particles and synthetic lipid microemulsions
of partially reconstituted LDL particles coated with the
apoproteins.
5) Physical Targeting :
• In this type of targeting some characteristics of
environment changes like pH, temperature, light
intensity, electric field, ionic strength small and even
specific stimuli like glucose concentration are used to
localize the drug carrier to predetermined site.
• This approach was found exceptional for tumour
targeting as well as cytosolic delivery of entrapped drug or
genetic material.

6) Dual Targeting :
• In this targeting approach carrier molecule itself
have their own therapeutic activity and thus
increase the therapeutic effect of drug.
• For example, a carrier molecule having its own
antiviral activity can be loaded with antiviral drug and
the net synergistic effect of drug conjugate was
observed.
7) Double Targeting :
• Temporal and spatial methodologies are combined
to target a carrier system, then targeting may be
called double targeting.
• Spatial placement relates to targeting drugs to
specific organs, tissues, cells or even subcellular
compartment. whereas temporal delivery refers to
controlling the rate of drug delivery to target site.

TYPES OF TARGETED DRUG DELIVERY SYSTEMTYPES OF TARGETED DRUG DELIVERY SYSTEM
Nano Tubes : They are hollow cylinder made of
carbon, atoms which can be filled and sealed for
potential drug delivery.
Application : Cellular scale needle for attaching drug
molecule to cancer cells. As an electrode in thermo
cells.

Nano wires : The nanowire pinpoint damage from injury
and stroke, localize the cause of seizures, and detect the
presence of tumours and other brain abnormalities.
Application : Technique has potential as a treatment for
Parkinson's and similar diseases.

Nanoshells : Nanoshells are hollow silica spheres
covered with gold. Scientists can attach antibodies to
their surfaces, enabling the shells to target certain
shells such as cancer cells.
Application : Technique has potential for targeting
cancerous drug.

Quantum dots : Quantum dots are miniscule
semiconductor particles that can serve as sign posts of
certain types of cells or molecules in the body.
Application : Technique has potential for targeting
cancerous drug.

Nano pores : Engineered into particles, they are holes
that are so tiny that DNA molecules can pass through
them one strand at a time, allowing for highly
precise and efficient DNA sequencing.
Application : Potential in genetic engineering
and bio technology.

Gold Nano : Particle Scientist uses gold nanoparticle to
develop ultrasensitive detection system for DNA and
protein markers associated with many forms of cancer,
including breast prostrate cancer.
Application : In cancer Treatment and Genetic
engineering.

Liposomes : Liposomes are simple microscopic vesicles
in which an aqueous volume is entirely composed by
membrane of lipid molecule various amphiphelic
molecules have been used to form liposomes. The
drug molecules can either be encapsulated in aqueous
space or intercalated into the lipid bilayers The extent
of location of drug will depend upon its physico-
chemical characteristics and composition of lipids.
Hydrophilic
Hy Hydrophobic

Niosomes : Niosomes are nonionic surfactant vesicles
which can entrap both hydrophilic and lipophilic drugs
either in aqueous phase or in vesicular membrane made up
of lipid materials It is reported to attain better stability
than liposome’s. It may prove very useful for
targeting the drugs for treating cancer, parasitic, viral
and other microbial disease more effectively.

Ufasomes : These are bilayer structures formed by
using single chain unsaturated fatty acids.
Pharmacosomes: The term pharmacosome comprises of
two main parts Pharmacon (active principle) and some
carriers postulated that amphipathic drug can self
assemble to form vesicle and these vesicles are termed
as pharmacosomes. Drug covalently bound to lipid may
exist in a colloidal dispersion as ultrafine, micelles or
hexagonal aggregates which are known as
pharmacosomes.

Virosomes : Virosomes are immuno modulating
liposomes consisting of surface glycoprotein of
influenza virus (immune stimulating reconstituted
influenza virosome) muramyl dipeptide etc. Virosomes
must be target oriented and their fusogenic
characteristics could be exploited in genome grafting and
cellular micro injection.

A. Interaction of the virosomes with cell surface recepters.
B. Release of the encapsulated drug molecules in the target cell.
Targeted drug delivery system

Cubosomes : Cubosomes are liquid crystalline phase
forming small cubic particles suitable for injection.
Nanocrystals : Nanocrystal is any Nano material with at
least one dimension ≤ 100nm and that is single
crystalline. More properly, any material with a dimension
of less than 1 micrometre, i.e., 1000 nanometers, should
be referred to as a nanoparticle, not a Nanocrystal. For
example, any particle which exhibits regions of
crystallinity should be termed nanoparticle or
nanocluster based on dimensions.

Transferosomes : A transferosomes, in functional terms,
may be described as lipid droplets of such deformability
that permits its easy penetration through the pores much
smaller than the droplets size.
• Transferosomes is a supramolecular entity that can pass
through a permeability barrier and there by transport
material from the other site.
• These are more elastic than standard liposomes.

RESEALEDRESEALED
ERYTHROCYTESERYTHROCYTES

Introduction:
Erythrocytes, the most abundant cells in the human body, have potential carrier
capabilities for the delivery of drugs. Erythrocytes are biocompatible, biodegradable,
possess long circulation half lives and can be loaded with a variety of biologically
active compounds using various chemical and physical methods.
Erythrocytes, also known as red blood cells, have been extensively studied for
their potential carrier capabilities for the delivery of drugs and drug-loaded
microspheres. Such drug-loaded carrier erythrocytes are prepared simply by
collecting blood samples from the organism of interest, separating erythrocytes from
plasma, entrapping drug in the erythrocytes, and resealing the resultant cellular
carriers. Hence, these carriers are called resealed erythrocytes. The overall process is
based on the response of these cells under osmotic conditions. Upon reinjection, the
drug-loaded erythrocytes serve as slow circulating depots and target the drugs to a
reticuloendothelial system (RES).

site specific drug delivery system

Morphology and physiology of erythrocytes
 Erythrocytes are the most abundant cells in the human body (5.4
million cells/mm3
blood in a healthy male and 4.8 million cells/mm3
blood in a healthy female).
 Its crucial role in oxygen delivery to various parts of the body.
 These are biconcave discs with an average diameter of 7.8 µm, a
thickness of 2.5 µm in periphery, 1 µm in the center and a volume of
85–91 µm3
.
 The flexible, biconcave shape enables erythrocytes to squeeze through
narrow capillaries, which may be only 3 µm wide.
 Erythrocytes are a highly specialized O2 carrier system in the body.
 Erythrocytes live only about 120 days.
 Worn-out erythrocytes are removed from circulation and destroyed in
the spleen and liver (RES), and the breakdown products are recycled.
The process of erythrocyte formation within the body is known as
erythropoiesis. In a mature human being, erythrocytes are produced in
red bone marrow under the regulation of a hemopoietic hormone called
erythropoietin .

Source and isolation of erythrocytes:
 Erythrocytes from mammalians like mice, cattle, pigs, dogs, sheep, goats,
monkeys, chicken, rats and rabbits.
 Fresh whole blood is the blood that is collected heparinized tubes by
venipuncture withdrawn from cardiac/splenic puncture in a syringe
containing a drop of anti coagulant, immediately chilled to 4ºC and stored
for less than 2 days.
 The erythrocytes are then seperated from serum coats by centrifugation at
2500rpm for 5 min at 4 ±1ºC and washed 3 times with phosphate buffer
solution (pH= 7.4).
 The washed cells are suspended in buffer solutions at various hematocrit
values as desired and are often stored in acid-citrate-dextrose buffer at 4ºC
for as long as 48 h before use.

Properties of resealed erythrocyte of novel drug
delivery carriers:
 The drug should be released at target site in a controlled manner.
 It should be appropriate size, shape and should permit the passage
through capillaries and Minimum leakage of drug should take place.
 It should be biocompatible and should have minimum toxic effect.
 It should possess the ability to carry a broad spectrum of drug.
 It should possess specific physicochemical properties by which desired
target size could be recognized.
 The degradation product of the carriers system, after release of the
drug at the selected site should be biocompatible. It should be physico-
chemically compatible with drug.
 The carrier system should have an appreciable stability during storage.

Advantages:
 Their biocompatibility, particularly when autologous cells are used,
hence no possibility of triggered immune response.
 Their biodegradability with no generation of toxic products.
 The considerably uniform size and shape of the carrier.
 Relatively inert intracellular environment .
 Prevention of degradation of the loaded drug from inactivation by
endogenous chemicals.
 The wide variety of chemicals that can be entrapped.
 They are non-immunogenic in action and can be targeted to disease
tissue/organ.
Disadvantage:
 They have a limited potential as carrier to non-phagocyte target tissue.
 Possibility of clumping of cells and dose dumping may be there.

Characteristic of Resealed Erythrocytes:
When erythrocytes are suspended in a hypotonic medium they swell to about one
and a half times their normal size, and the membrane rupture in the formation of
pores with diameters of 200 to 500 Å. The pores allow equilibration of the
intracellular and extracellular solution.
If the ionic strength of the medium then is adjusted to isotonic and the cells are
incubated at 37ºC, the pores will close and cause the erythrocyte to “Resealed”.
Using this technique upto 40% of drug can be entraped in the resealed erythrocytes
from the extracellular solution. So, this systems are used for targeted delivery via
intravenous injection.
Normal aging erythrocytes, slightly damaged erythrocytes, slightly damaged
erythrocytes and those coated lightly with antibodies are sequestered in the spleen
after intravenous vein fusion, but heavily damaged or modified erythrocytes are
removed from the circulation by the Liver.
Red cells
placed in
hypotonic
drug solutions
Lysis of cells
and entry of
drug
Resealed red
cells loaded
with drug

Membrane
perturbation
Electro
encapsulation
Hypo-osmotic
lysis
Lipid fusion
method
Dialysis method
Preswell method
Dilution method
METHODS OF DRUG LOADING IN
RESEALED ERYTHROCYTES
Osmotic-lysis
Endocytosis
method
Normal transport
mechanism

HYPO OSMOTIC LYSIS METHOD
 Dialysis method:
- In this method, erythrocyte suspension + Drug solution → dialysis tube and both
ends are tied with thread.
- This tube is placed in bottle containing 100ml of swelling solution at stored at 4ºC
for lysis.
- After, the dialysis tube is transferred to 100ml resealing solution (isotonic PBS, pH
7.4 ) at room temp. (25º-30ºC) for resealing.
- These resealed cells are removed and washed with PBS at 4ºC and finally
suspended in PBS solution.
- The limitation of dilution method can be overcome by carrying out lysis and
resealing in the same dialysis tube.

Dilution method:
- When these RBC are placed in the hypotonic (0.4% NaOH) they get ruptures
permitting escape of cellular content and equilibrium is achieved within 1min, which
results in swelling upto 1.6 time its initial volume.
- At 0ºC, opening permits to attain equilibrium for inter- and extra cellular fluids
through the pore size of 200-500Å.
- Increasing the ionic strength at 37ºC, results in resealing of cell membrane and
restoring the osmotic property.
- This method is simple and faster, but have very low encapsulation efficiency (1-8%)
and lose of cytoplasmic constituents during osmotic lysis.
- Low mol. wt. drugs like ß-glucosidase and ß-galactosidase can be encapsulated.
Osmotic lysis:
- In this technique, haemolysis in isotonic solution can be achieved by either chemical
or physical means or both.
- Erythrocytes are incubated in drug solution with high transerythrocytic membrane
permeability like PEG or NH4Cl or Urea which offers osmotic diffusion until it
reaches equilibrium.
- Then the solution was diluted with an isotonic-buffered drug solution.
- These cell are separated, washed and resealed at 37ºC.
Eg: Dimethyl sulphoxide (DMSO), monosaccharides, sucrose, etc.,

 Preswell dilutional haemolysis:
- This technique is based upon initial controlled swelling in hypotonic buffered
solution.
- The principle involved in this technique is swelling of erythrocytes without lysis by
placing them in slightly hypotonic solution and centrifugation with low speed at
0ºC for 5min.
- To this add small volume of drug solution at the point of lysis.
- This techniques results in retention of cytoplasmic constituents and 72% of drug
entrapment.
Eg: Thyroxin, Ibuprofen, etc.,

ELECTRIC BREAKDOWN TECHNIQUE:
- Used for entrapment of bioactive molecules. It is also known as “Electroporation
method”..
- The erythrocyte membrane is opened by the dielectric breakdown.
- Firstly, erythrocytes are suspended in an isotonic buffered solution in electric
discharge chamber connected to the capacitor and external circuit.
- The charge is discharged at definite voltage within definite time interval through
cell suspension to produce a square-wave potential.
- The optimum intensity of an electric field is between 1-10 kW/cm and optimum
discharge time is 20-160µs.
- The compound which is to be entrapped was added to the medium.
- After certain time the cell suspension was transferred to a pre-cooled tubes and kept
at 4ºC.
- Resealing of electrically perforated erythrocytes membrane is then affected by
incubation at 37ºC in an osmotically balanced medium.
- Major advantage is uniform distribution of drug loading is achieved and possible to
entrap upto 35% of drug.
- Disadvantage is need sophisticated and special instruments and time consuming.
Eg: Sucrose, Urea, Methotrexate, Glucophorin, etc.,

ENDOCYTOSIS METHOD:
- In this method, 1vol. of packed erythrocytes + 9 vol. of buffer (containing 2.5mM
ATP, 2.5mM MgCl2 and 1mM CaCl2) and incubated for 2min at room temperature.
- The pores created in this method are resealed by using 154mM of NaCl and incubate
at 37ºC for 2min.
- The entrapment of drug was obtained by endocytosis.
- In this method, the vesicle membrane separates the endocytosed substance from the
cytoplasm containing drug, which are sensitive to inactivation of cytoplasmic
enzyme and protect from erythrocyte membrance.
Eg: 8-amino quinolines, Vinblastin, Chlorpromazine, Phenothiazines, hydrocortison,
propanolol, tetracine, VitA, etc.,

LIPID FUSION METHOD:
- Lipid vesicles containing a drug can be directly fused to human erythrocytes, which
leads to an exchange with a lipid-entrapped drug.
- Entrapment efficiency is very low (~1%).
Eg: Inositol monophosphate to improve the O2 carrying capacity of RBC.
MEMBRANE PERTURBATION:
- This method is based on increase in membrane permeability of erythrocytes when
exposed to certain chemicals.
Eg: Amphotericin-B, Daunomycin using Halothane.
NORMAL TRANSPORT MECHANISM:
- The biological active components are entrapped in erythrocytes without dispruting
the erythrocyte membrane by incubating in drug solution for varying period of time.
- 30-35% of drug can be entrapped.

IN-VITRO STORAGE:
- The most common storage media is Hank’s balanced salt solution and acid-citrate-
dextrose at 4ºC and can retain their physiological and carrier characteristics for at
least 2weeks.
- Addition calcium-chelating agent (or) purine nucleosides improve circulation
survival time of cell upon reinjection.
- DMSO, dimethyl-3,3-di-thio-bispropionamide, gluteraldehyde, toulene-2,4-
diisocynate are used to stabilize the membrane of RSE and enhance stability upon
storage.
Disadv.:- At high conc. of membrane stabilizers, reduces circulation survival time.
S.NoS.No ChemicalsChemicals QuantityQuantity
01.01. Potassium PhosphatePotassium Phosphate 0.44 mM0.44 mM
02.02. Potassium ChloridePotassium Chloride 5.37 mM5.37 mM
03.03. Sodium Phosphate, DibasicSodium Phosphate, Dibasic 0.34 mM0.34 mM
04.04. Sodium ChlorideSodium Chloride 136.89 mM136.89 mM
05.05. D-GlucoseD-Glucose 5.55 mM5.55 mM
Hank’s balanced salt solution (HBSS)

 CHARACTERIZATION OF RESEALED ERYTHROCYTES
(a) Drug content estimation,
(b) In-vitro drug release and hemoglobin content,
(c) Percent cell recovery,
(d) Osmotic fragility,
(e) Osmotic shock,
(f) Turbulence shock,
(g) Erythrocyte sedimentation rate (ESR),
(h) Determination of entrapped magnetite,
(a) Drug content estimation:
- 0.5ml of loaded cells + 2.0ml of Acetonitrile and centrifuge at 2500rpm.
- The supernatant liquid is collected and analyzed for drug content.
(b) Percent cell recovery:
It is determined by counting no. of intact cells per cubic mm of packed
erythrocytes using laser scattering.

(c) In-vitro drug release and haemoglobin content
- Initially collect cell suspension (5% hemotocrit in PBS) and stored in 4ºC in
amber colored bottle.
- Periodically the clear supernatant are withdrawn using hypodermic needle
equipped with 0.45µ filter and deprotinised using methanol and were estimated
for drug content.
(d) Osmotic fragility:
Normal and loaded erythrocytes of drug are incubated separately in stepwise
decreasing % of NaCl solution (0.9 and 0.1%) at 37±2ºC for 10min and
centrifugation at 2000 rpm for 10min. The supernatant examined for drug and
hemoglobin content.
(e) Osmotic shock:
In this study, 1ml of erythrocyte suspension were diluted with distilled water of
5ml and centrifuged at 3000rpm for 15min. The supernatent liquid was estimated
for hemoglobin spectrophotometrically.
=
A540 of sample - A540 of background
A540 of 100% hemoglobin
% Hemoglobin release

(f) Turbulence shock:
- It is the measure of simulating destruction of loaded cells during injection.
- In this method, the normal and drug loaded cells are passed through a 23 gauge
hypodermic needle at a flow rate of 10ml/min which is comparable to that of
blood. The samples are with drawn and centrifuged for 2000rpm for 10min and
estimated for hemoglobin content.
- Drug loaded erythrocytes found to be less resistant to flow and causes
distruction.
(g) Determination of entrapped magnitude:
- Initially, Hcl is added to a fixed amount of magnitude bearing erythrocytes and
content are heated to 60ºC for 2hrs.
- to this added 20%w/v Tricholoroacetic acid is added and supernatent liquid is
obtained after centrifugation.
- This was analyzed for magnitude concentration by using AAS.
(h) Erythrocyte sedimentation rate (ESR):
- Sedimentation depends upon the size and no. of cells and relative concentration
to the plasma proteins, fibrogen and α- & ß- globulines.
- The test is performed by determination of rate of sedimentation in the standard
tube.
- Normal blood ESR is 0-15mm/hr. Higher rate indicates active but obscure
disease processes.

Applications of resealed erythrocytes:
 Drug targeting: these can act as drug carriers and targeting tool. Used to
target organs of mononuclear phagocytic system/ reticuloendothelial
system because the changes in the membrane are recognized by
macrophages.
Eg: Urease capsules in treatment of kidney failure for maintenance of
serum urea levels.
 Targeting RES organs: damaged erythrocytes are rapidly cleared from
circulation of phagocytic Kupffur cells in liver and spleen.
- Targeting organs like liver and spleen, by modification of Resealed
erythrocyte membrane with various antibiotics, gluteraldehyde,
carbohydrate, sulphydryl, etc.,
 Treatment of hepatic tumors: Antineoplastic drugs like Methotrexate,
Bleomycin, Asparginase and Adrimycin delivered by RES.
 Treatment of parasitic diseases: Antimalarial, antileishmanial and
antiamoebic drugs can be delivered.
Eg: Pentamidine loaded immunoglobin-G coated erythrocytes against
macrophage-cantained leishmania.
 Removal of RES iron overload: Desferrioxamine, an iron-chelating drug
in erythrocyte ghosts with a view to promote excretion of iron in patients
with excess body stores.

MONOCLONALMONOCLONAL
antibodiesantibodies

Beginning of Monoclonal EraBeginning of Monoclonal Era
Georg Kohler and Cesar Milstein fuse
mouse lymphocytes with neoplastic
mouse plasma cells to yield hybridomas
that produce specific antibodies. This
offers a limitless supply of monoclonal
antibodies. Monoclonal antibodies permit
diagnostic tests that are specific, and
function as probes.

Discovery of Monoclonal AntibodiesDiscovery of Monoclonal Antibodies
 Monoclonal
antibodies were
produced in mice
using a technique
described by
Köhler and
Milstein et al..
They were awarded
the Nobel Prize in
1984 (along with
Jerne) for their
work.

Nobel prize in Medicine and PhysiologyNobel prize in Medicine and Physiology
waswas awarded toawarded to Köhler, MilsteinKöhler, Milstein andand
Jerne in 1984Jerne in 1984

Monoclonal AntibodiesMonoclonal Antibodies
Monoclonal antibodies are
Monospecific antibodies that are
identical because they are produced by
one type of immune cell that are all
clones of a single parent cell. Given
(almost) any substance, it is possible to
create monoclonal antibodies that
specifically bind to that substance

NomenclatureNomenclature
The nomenclature of monoclonal
antibodies is a naming scheme for
assigning generic, or non-proprietary,
names to a group of medicines called
monoclonal antibodies. This scheme is
used for both the World Health
Organization’s International Non-
proprietary Names and the United States
Adopted Names

Study of Myeloma leads to DiscoveryStudy of Myeloma leads to Discovery
of Monoclonal antibodiesof Monoclonal antibodies
 In the 1970’s the B-cell
cancer myeloma was
known, and it was
understood that these
cancerous B-cells all
produce a single type
of antibody.This was
used to study the
structure of antibodies,
but it was not possible
to produce identical
antibodies specific to a
given antigen.

Fusion of Mice spleen cells with MyelomaFusion of Mice spleen cells with Myeloma
cells produced Monoclonal antibodiescells produced Monoclonal antibodies

Characters of MonoclonalCharacters of Monoclonal
AntibodiesAntibodies
Monoclonal antibodies (mAb) are a
single type of antibody that are identical
and are directed against a specific epitope
(antigen, antigenic determinant) and are
produced by B-cell clones of a single
parent or a single hybridoma cell line. A
hybridoma cell line is formed by the
fusion of a one B-cell lymphocyte with a
myeloma cell. Some myeloma cells
synthesize single mAb antibodies naturally

Hybridoma creates MonoclonalHybridoma creates Monoclonal
antibodiesantibodies
 Monoclonal antibodies are
typically made by fusing
myeloma cells with the
spleen cells from a mouse
that has been immunized
with the desired antigen.
However, recent advances
have allowed the use of
rabbit B-cells.

Producing Monoclonal antibodiesProducing Monoclonal antibodies
 First, a mouse is
inoculated with the
antigen to which the
MA are to be
produced.After this,
the spleen is removed
and fused with
myeloma cells in
order to produce the
hybridomas that will
be selected according
to the antibody
produced.

Hybridoma leads toHybridoma leads to
ProliferationProliferation

Principles in HybridomaTechnologyPrinciples in HybridomaTechnology
 inject the protein into a
mouse.
 - remove the spleen.
 - identify which spleen
cells are producing
antibodies.
 - separate these cells and
grow in tissue culture
tubes.
 - screen each Ab for
cross reactivity.
 - select the Ab which
doesn't cross react with
any other protein.

Monoclonal antibodies are producedMonoclonal antibodies are produced
by Hybridoma techniqueby Hybridoma technique

Monoclonal – Diagnostic useMonoclonal – Diagnostic use
 Although monoclonal
antibodies were first
produced in 1975 as
research tools,
scientists quickly
recognized their
practical uses,
especially in diagnostic
tests and in therapy.
Several diagnostic
procedures that use
monoclonal antibodies
are now available

A breakthrough in DiagnosticsA breakthrough in Diagnostics
 A monoclonal antibody can
be used to detect
pregnancy only 14
days after conception.
Other monoclonal
antibodies allow rapid
diagnosis of hepatitis,
influenza, herpes,
streptococcal, and
Chlamydia infections.

Helps in Critical Diagnostic decisionsHelps in Critical Diagnostic decisions
They can be used to
detect for the presence
and quantity of this
substance, for instance
in a Western blot test
(to detect a substance
in a solution) or an
immunofluorescence
test.

Monoclonal's helps InMonoclonal's helps In
Immunodiagnostic testsImmunodiagnostic tests
Monoclonal
antibodies can also
be used to purify a
substance with
techniques called
immunoprecipitat
ion and affinity
chromatography.

Limitations with Mouse MonoclonalsLimitations with Mouse Monoclonals
Problem in medical
applications is that the
standard procedure of
producing monoclonal
antibodies yields mouse
antibodies, and these
are rejected by the
human immune system

Finding solutions for Human useFinding solutions for Human use
 In one approach, one takes
the DNA that encodes the
binding portion of
monoclonal mouse
antibodies and merges it
with human antibody
producing DNA, in order to
make bacteria produce
antibodies that are half
mouse and half human.

Conjugated monoclonal antibodyConjugated monoclonal antibody
therapy:therapy:
 Toxins or radioactive
isotopes are bound to
the constant region of
the MAbs.When the
MAb binds to the
surface cells of a
tumor the toxin or
radioactivity will kill
the cancer cells and all
cells within a certain
radius (a killing zone).
In this way cancer
cells within the tumor
will be killed

Knowledge on Monoclonal’sKnowledge on Monoclonal’s
advancesadvances
Mice have been genetically engineered to
produce antibodies that have human constant
regions (this is the part of the antibody that the
human immune system recognizes as being
foreign (mouse)). By using these hybrid (or
chimeric monoclonal antibodies with human
constant regions, the immune system only
"sees" a human protein and does not react
against them. So, they can be injected many
times to kill all of the cells in a tumor.

Monoclonal antibodies for cancerMonoclonal antibodies for cancer
treatmenttreatment
 Possible treatment for
cancer involves
monoclonal antibodies that
bind only to cancer cells
specific antigen and induce
immunological response on
the target cancer cell
(naked antibodies). mAb can
be modificated for delivery
of [toxin], radioisotope,
cytokine.

FDA approvesFDA approves
The example described
in class is Herceptin.
These monoclonal
antibodies can be used
against certain forms of
breast cancer and have
passed clinical trials and
been approved for use
by the FDA.

FDA approves andTrails onFDA approves andTrails on
 The first FDA-approved
therapeutic monoclonal
antibody was a murine IgG2a
CD3 specific
transplant rejection drug,
OKT3 (also called
muromonab), in 1986.This
drug found use in solid
organ transplant recipients
who became steroid resistant.
Hundreds of therapies are
undergoing clinical trials. Most
are concerned with
immunological and oncological

THANK YOU FORTHANK YOU FOR
YOUR ATTENTIONYOUR ATTENTION

site specific drug delivery system

More Related Content

What's hot (20)

Similar to site specific drug delivery system (20)

Recently uploaded (20)

site specific drug delivery system