3. 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.
4. • Erythro= red
• Cytes = cell
• Biconcave discs, anucleate.
• Filled with hemoglobin (Hb),
a protein that functions in
gas transport.
• Erythrocyte ghosts: RBC
without hemoglobin
5. 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
6. 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.
7. 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.
8. 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
9. 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.
10. 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.
11. 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.
16. RBC
0.6%w/v NaCl Swelled
RBC
5 min
incubation
at 0 0c
Drug + Loading
buffer
Loaded
RBC
Resealed
RBC
Incubation
at 25 0c
Resealing
Buffer
Efficiency 72% Fig:- Preswell Method
17. 80 %
Haematocrit
value
RBC
+
Phosphate
buffer
Placed in dialysis
bag with air
bubble
Dialysis bag placed in 200ml of
lysis buffer with mechanical
rotator 2hrs 4 0C
Drug
Loading
buffer
Loaded RBC
Dialysis bag placed in Resealing
buffer with mechanical rotator
30 min 37c.
Resealed RBC
Efficiency 30-45%
18. 2.2 Kv Current
for 20 microsec
At 250 C
Pulsation
medium
RBC
+
Drug
+
Loading
suspension
3.7 Kv Current for
20 micro sec
Isotonic
NaCl
Loaded RBC
Resealing
Buffer
Resealed RBC
Fig:- Electro-encapsulation Method
21. METHOD %LOADING ADVANTAGES DISADVANTAGES
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
22. Characteriztion of resealed erythrocytes
Physical, cell related, biological characterization
Characterization parameter Analytical methods. instrument
PHYSICAL CHARACTERIZATION
Shape and surface
morphology
TEM, SEM, phase contrast microscopy
Vesicle size and size
distribution
TEM, optical microscopy
Drug release Diffusion cell/ dialysis
% Entrapment Deprotonation and assay of released drug/
radio labelling
Electrical surface charge or
surface PH
Zeta potential, PH sensitive probes
22
23. Characterization parameter Analytical methods. instrument
CELL RELATED CHARACTERIZATION
% Haemoglobin Deprotonation, assay for Hb, laser light
scattering
Mean corpuscular
Haemoglobin (g/100
ml)/erythrocyte count)
Light scattering
% Cell recovery Haematological analyzer, Neubeur’s chamber
Osmotic fragility Stepwise incubation to hypotonic saline,
estimate drug and Hb
Osmotic shock Dilution with distilled water and estimate drug
Turbulent shock Pass through 23 gauge needle(10 ml/min),
estimate residual drug
Erythrocyte sedimentation
rate
ESR apparatus
BIOLOGICAL CHARACTERIZATION
Sterility Culture techniques
Pyrogenicity LAL test, Rabbit fever response
23
24. 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
