This document discusses the use of erythrocytes (red blood cells) as drug delivery carriers. It describes how erythrocytes can be loaded with drugs through various methods like hypotonic lysis, dialysis, and electroencapsulation. Loaded erythrocytes are then resealed to form drug-loaded carrier erythrocytes. Erythrocytes offer benefits as carriers including biocompatibility, long circulation times, and the ability to encapsulate large drug volumes. However, limitations include potential drug leakage and an inability to target non-phagocytic tissues. The document reviews various loading methods and their efficiencies.

1. Presented By
Bindiya Patel
M.PHARM
(PHARMACEUTICS)

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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.

13. Drug loading
in Resealed
erythrocytes
Electro
encapsulation
Membrane
perturbation
Hypo-osmotic
lysis
Dialysis
method
Osmotic-lysis
Preswell
method
Dilution
method
Lipid fusion
endocytosis

14. RBC
0.4% NaCl
Hypotonic
Membrane ruptured
RBC
Drug
Loading
buffer
Loaded RBC
Resealed Loaded
RBC
Resealing
buffer
Incubation
at 250C
Hypotonic
medium
Isotonic
medium
Washed
Efficiency  1-8%

15. RBC Isotonically
ruptured RBC
Chemical – urea, polyethylene, polypropylene, and NH4Cl
Physical
rupturing
Chemical
rupturing
Drug Isotonic
Buffer
Loaded RBC
Resealed RBC
Incubation
at 250 C

16. RBC
0.6%w/v NaCl Swelled
RBC
Drug + Loading
buffer
5 min
incubation
at 0 0c
Loaded
RBC
Incubation
at 25 0c
Resealing
Buffer
Resealed
RBC
Efficiency  72% Fig:- Preswell Method

17. RBC
Phosphate
buffer
+
80 %
Haematocrit
value
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 RBCDialysis bag placed in Resealing
buffer with mechanical rotator
30 min 37c.
Resealed RBC
Efficiency  30-45%

18. RBC
2.2 Kv Current
for 20 microsec
At 250 CPulsation
medium
+ +
Drug
Loading
suspension
3.7 Kv Current for
20 micro sec
Isotonic
NaCl
Loaded RBC
Resealing
Buffer
Resealed RBC
Fig:- Electro-encapsulation Method

19. RBC
Drug
Suspension
+
Buffer containing ATP,
MgCl2, and CaCl2
At 250 C
Loaded RBC
Resealing
Buffer
Resealed RBC
Fig : Entrapment By Endocytosis Method

20. RBC
Amphotericin B
e.g. Chemical
agents
Increased
permeability of
RBC Resealing
Buffer
Drug
Resealed RBC

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.  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