Resealed erythrocytes
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Transcript of Resealed erythrocytes
Resealed Erythrocyte
As Drug Carrier
Presented By Bindiya Patel
M.PHARM (PHARMACEUTICS)
CONTENT
Introduction
Why erythrocyte as carrier
Source and isolation of erythrocytes
Advantages
Limitation
Drug carrying potential of RBC
Effects of tonicity on RBC
Method of loading
Reference
INTRODUCTION
Erythrocytes have been the most extensively investigated and
found to posses great potential in novel drug delivery .
Erythrocytes are loaded with drug/enzymes & provide target
drug delivery system.
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.
CONT...
• Erythro= red
• Cytes = cell
• Biconcave discs, anucleate.
• Filled with hemoglobin (Hb), a protein that functions in gas transport.
• Erythrocyte ghosts: RBC without hemoglobin
Why Erythrocyte As Carrier ???
Erythrocytes are potential biocompatible vectors for different
bioactive substances, biological carriers of drugs, and enzymes.
Erythrocytes loaded with drugs and other substances allow for
different release rates to be obtained.
Encapsulation in erythrocytes significantly changes the
pharmacokinetic properties of drugs in both animals and
humans, enhancing liver and spleen uptake and targeting the
reticulo-endothelial system (RES).
Encapsulation of new prodrugs with increased duration of action,
etc
Cont...
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, the most abundant cells in the human body,
have potential carrier capabilities for the delivery of drugs.
They capability for prevention of premature degradation or
inactivation.
Source And Isolation Of Erythrocytes
Source:- mice, cattle, pig, dog, sheep, goat, monkey,
chicken, rat, rabbit & human.
Whole blood can be collected by venipuncture or from
orbital sinus in heparinized tube.
EDTA or heparin can be used as anticoagulants agents.
Fresh blood is used for loading of drugs.
Biodegradable Isolation is easy Non immunogenic large volume of drug can be encapsulated in small volume
of erythrocytes Prolong systemic activity of drug Reduce Adverse Effect Peptide & Enzyme Delivery
Advantages
Limitation
They have a limited potential as carrier to non-phagocytic target
tissue.
Possibility of Leakage of the cells and dose dumping may be
there.
Several molecules may alter the physiology of the erythrocyte.
Liable to biological contamination due to the origin of the blood,
the equipment and the environment.
Drug Carrying Potential Of RBC
The carrier potentials of these cells was first realized in
early 1970.
The developing RBC has capacity to synthesize hemoglobin,
however, adult RBCs do not have this capacity and serve as
carriers for hemoglobin.
Drug which are normally unable to penetrate the
membrane, should be made to transverse the membrane
without causing any irreversible changes in the membrane
structure and permeability.
Cont...
Cells must be able to release the entrapped drug in a
controlled manner upon reaching the desired target.
The processing of drug entrapment requires a reversible
and transient permeability change in the membrane, which
can be achieved by various physical and chemical means.
Effects Of Tonicity On RBC
Method Of Loading
Drug loading in Resealed erythrocytes
Electro encapsul
ation
Membrane perturbati
on
Hypo-osmotic
lysis
Dialysis method
Osmotic-lysis
Preswell method
Dilution method
Lipid fusion endocytosi
s
Dilution Haemolysis
RBC0.4% NaCl
HypotonicMembrane ruptured
RBC
Drug
Loading buffer
Loaded RBC
Resealed Loaded RBC
Resealing buffer
Incubation at 250C
Hypotonic medium
Isotonic medium Washed
Efficiency 1-8%
Isotonic Osmotic Lysis
RBC Isotonically ruptured RBC
Chemical – urea, polyethylene, polypropylene, and NH4Cl
Physical rupturing
Chemicalrupturing
DrugIsotonicBuffer
Loaded RBC
Resealed RBC
Incubation at 250 C
Preswell Dilutional Haemolysis
RBC
0.6%w/v NaCl
Swelled RBC Drug +
Loading buffer
5 min incubation at 0 0c Loade
d RBC
Incubation at 25 0c
Resealing Buffer
Resealed RBC
Efficiency 72% Fig:- Preswell Method
Dialysis
RBC
Phosphate buffer
+
80 % Haematocri
t value
Placed in dialysis bag
with air bubble
Dialysis bag placed in 200ml of lysis buffer with mechanical rotator 2hrs
4 0C
DrugLoading
buffer
Loaded RBC
Dialysis bag placed in Resealing buffer with
mechanical rotator 30 min 37c.
Resealed RBC
Efficiency 30-45%
Electroinsertion Or Electro-encapsulation
RBC
2.2 Kv Current for 20 microsecAt 250 CPulsatio
n medium
+ +Drug
Loading suspension
3.7 Kv Current for 20 micro
sec
Isotonic NaCl
Loaded RBC
Resealing Buffer
Resealed RBC
Fig:- Electro-encapsulation Method
Entrapment By Endocytosis
RBC
Drug Suspensi
on
+
Buffer containing ATP, MgCl2, and
CaCl2At 250 C
Loaded RBC
Resealing Buffer
Resealed RBC
Fig : Entrapment By Endocytosis Method
Membrane Perturbation Method
RBC
Amphotericin B
e.g. Chemical agents
Increased permeability
of RBC Resealing Buffer
Drug Resealed
RBC
Comparison Of Various Hypo-osmotic Lysis Method
METHOD
%LOADINGADVANTAGE
SDISADVANTAGE
S
Dilution method 1-8%
Fastest & simplest
especially for low molecular weight drugs
Entrapment efficiency is very
less (1-8%)
Dialysis 30-45%
Better in vitro survival of
membrane due to lesser ionic
load
Time consuming; heterogeneous size
distribution of resealed
erythrocytes
Preswell dilution 20-70%
Good retention of cytoplasm
constituents & good survival in
vivo.
-
Isotonic osmotic
lysis-
Better in vivo surveillance
Impermeable to large molecules , process is time
consuming
REFERENCES
Jain.S., Jain.N.K., resealed erythrocytes as drug carriers, Edited
Jain N.K., Controlled And Novel Drug Delivery, New Delhi, CBS
publishers, New Delhi, 2004, 256-281.
Vyas S.P., Khar R.K., Targeted And Controlled Drug Delivery:
Novel Carrier Systems, New Delhi, CBS publisher, 2004, 387-413.
Indian Journal of Pharmaceutical Education & Research Vol.
43(4), Oct-Dec, 2009 , 375-386 Journal of Controlled Release
(2004) 27– 49