COVERING LETTER
Date: 26-02-2014
Place: Greater Noida
From,
Roobi Singh
Department of Pharmacy, School of Medical and Allied Sciences, Galgotias University, Plot
No.2, Sector 17-A, Yamuna Expressway, Greater Noida, Gautam Buddh Nagar, Uttar Pradesh,
India.
Mobile no: +91 7827642549
Email: rubisingh08.nnm@gmail.com
To
The Editor-in-Chief,
Journal of Pharmaceutical and Biological Sciences,
Web: http://www.jpabs.com
Sub: Submission of Manuscript
Article Type: - Review Article
Dear Editor,
With reference to the above, please find my submission of paper entitled with
“Methods and Evaluation Parameter of Sustained Release Muco-Adhesive Microsphere’
For possible publications in your esteemed journal.
I hereby affirm that the content of this manuscript is original. Furthermore it has been neither
Published elsewhere fully or partially or any language nor submitted for publication (fully or
Partially) elsewhere simultaneously.
I also affirm that all the authors have seen and agreed to the submission of paper and their
Inclusion of name(s) as co-author(s).
I am looking forward to hear from you.
Thanking you
Sincerely yours,
ROOBI SINGH
TITLE PAGE
METHODS AND EVALUATION PARAMETER OF SUSTAINED
RELEASE MUCO-ADHESIVE MICROSPHERE
Rubi Singh*, Pramod Kumar Sharma, Prashant Dhakad, Nitin Kumar, Rishabh Malviya
Department of Pharmacy, School of Medical and Allied Sciences, Galgotias University, Plot
No.2, Sector-17A, Yamuna Expressway, Greater Noida, Gautam Buddh Nagar, Uttar Pradesh,
India.
*Corresponding Author
Rubi Singh
Email: rubisingh08.nnm@gmail.com
Contact no- 07827642549
Department of Pharmacy, School of Medical and Allied Sciences, Galgotias University, Plot
No.2, Sector-17A, Yamuna Expressway, Greater Noida, Gautam Buddh Nagar, Uttar Pradesh,
India.
ABSTRACT
Microsphere are free flowing powder, consist of spherical particle of size ideally less than 1 to
1000 µm. Each particle of microspheres is basically a matrix of drug dispersed in a polymer from
which release obtained by a first order kinetic process. In the microsphere, the polymer used are
biodegradable and biocompatible. Internal structure of microspheres is a matrix of drug and
polymeric excipient. The microspheres are meant to reduce the dosing frequency and improve
patient compliance by designing and evaluating sustained release mucoadhesive microspheres
for effective control of disease. Mucoadhesive drug delivery system are delivery system which
utilizes the property of bio-adhesion of certain polymers which become adhesive on hydration
and can be used for targeting a drug to a particular region of the body for extended periods of
time.
Keywords; Mucoadhesive microsphere, mucoadhesion, biodegradable, mucoadhesive polymer,
bio-adhesive polymer.
INTRODUCTION
Mucoadhesive microsphere is a targeting drug delivery system in a particular surface of the body
for extended period of time. A good Sustained Release Mucoadhesive (SRM) drug dosage form
has three properties, from a technological point of view. The delivery system must maintain drug
position in the mouth for a few hours, release the drug in a controlled manner and provide the
drug release in a unidirectional way towards the mucosa. Microspheres play an important role in
the novel drug delivery system. Success of these microspheres is limited owing to their short
residence time at the site of absorption1. This system uses the property of bio adhesion of certain
polymers which become adhesive on hydration and can be used for targeting a drug to a
particular surface of the body. The “mucoadhesion” word is being used for the adhesion of the
polymers with the surface of the mucosal layer. The attachment could be between an artificial
material and biological substrate such as adhesion between polymer and a biological membrane.
The word mucoadhesion is preferred when the mucosal layer lines a number of regions of body
including a gastrointestinal tract, urogenital tract, the airways, the ears and eyes2.
ADVANTAGES3.

Increase bioavailability

Efficient absorption

Prolonged gastro- intestinal time

High surface to volume ratio which ensure a much more intimate contact with mucosal
layer

Specific targeting of drug to absorption site

Better control of systemic drug delivery
POLYMER USED FOR MUCOADHESIVE MICROSPHERE SYSTEM - There are
different types of polymer used in mucoadhesive microsphere4.
Synthetic polymers Natural polymers

Cellulose derivative

Polycarbophil

Sodium alginate

Poly (ethylene oxide)

Poly (vinyl pyrrolidone)

Poly (vinyl alcohol)

Poly (hydroxyethyl methyl acrylate)

Hydroxyl propyl cellulose
Natural polymers

Tragacanthe

Sodium alginate

Karaya gum

Guar gum

Gelatin

Chitosan

Soluble starch
Patent NO.
8197435
Title
Result
Methods and devices for drug
Methods
delivery to ocular tissue using
provided
microneedle.
administration of a drug to a
and
for
devices
are
targeted
patient's eye5.
7691811
Transporter-enhanced
Methods and compositions for
corticosteroid activity and
enhancing the activity and/or
methods and compositions for
duration
treating dry eye.
loteprednol
of
action
of
etabonate
and
other soft anti-inflammatory
steroids of the haloalkyl 17αalkoxycarbonyloxy-11βhydroxyandrost-4-cn-3-one
17β-carboxylate type and the
corresponding
Δ1,4-
compounds are described6.
Anti-TNF antibodies,
The present invention relates
compositions, methods and uses.
8603778
to anti-TNF antibodies
comprising all of the heavy
chain variable CDR regions of
SEQ ID NOS:1, 2 and 3
and/or all of the light chain
variable CDR regions of SEQ
ID NOS:4, 5 and 6, specific
for at least one human tumor
necrosis factor alpha (TNF)
protein or fragment thereof, as
well as nucleic acids encoding
such anti-TNF antibodies,
complementary nucleic acids,
vectors, host cells, production
methods and therapeutic
methods7.
4743545
Hollow porous microspheres
Biocatalyst such as enzymes
containing biocatalyst
or cells are immobilized in
hollow porous microspheres
for use as bioreactors in
biochemical processes8.
6235313
Bioadhesive microspheres and
Bioadhesive polymers in the
their use as drug delivery and
form of, or as a coating on,
imaging systems.
microcapsules
containing
drugs or bioactive substances
which
may
therapeutic,
serve
or
for
diagnostic
purposes in diseases of the
gastrointestinal
described9.
tract,
are
6315981
Gas filled microspheres as
Novel gas filled microspheres
magnetic resonance imaging
useful as magnetic resonance
contrast agents.
imaging (MRI) contrast agents
are provided10.
5922304
Gaseous precursor filled
Novel gas filled microspheres
microspheres as magnetic
useful as magnetic resonance
resonance imaging contrast
imaging (MRI) contrast agents
agents.
are provided11.
Bioadhesive polymers in the
6365187
Bioadhesive microspheres and
form of, or as a coating on,
their use as drug delivery and
microcapsules
imaging systems.
drugs or bioactive substances
which
containing
may
therapeutic,
serve
or
for
diagnostic
purposes in diseases of the
gastrointestinal
tract,
are
described12.
5972387
Modified hydrolyzed vegetable
Modified
hydrolyzed
protein microspheres and
vegetable
protein
methods for preparation and use
microspheres and methods for
thereof.
their preparation and use as
oral
delivery
systems
for
pharmaceutical
agents
are
described13.
5186922
Use of biodegradable
The invention relates to an
microspheres labeled with
inexpensive and easy to use
imaging energy constrast
method
of
materials.
arterial
circulation,
biodegradable
visualizing
an
using
microspheres
which are permeated with an
imaging
energy
absorbent
contrast material, such as an
X-ray
absorbent
material,
which enables the diagnosis of
pulmonary embolism14.
METHODS –
Coacervation: This method is performed in mainly three steps carried out under continuous
agitation which are formulation of three immiscible chemical phases, deposition of coating,
and rigidization of the coating. Three immiscible phases include a liquid manufacturing vehicle,
a core material phase and a coating material phase. The core material is dissolved in a solution of
the polymer, the solvent for the polymer being the liquid manufacturing vehicle phase. By
changing the temperature of the polymer solution, microsphere can be prepared, by adding salt,
using a non solvent, and also by the addition of an incompatible polymer to the polymer solution
and polymer-polymer interaction15.
Ionic gelation: In this ionic gelation method drug is added to aqueous solution of sodium
alginate. Alginate/chitosan particulate systems for diclofenac sodium release have been prepared
using this ionic gelation technique. In this order to get the complete solution stirring is continued
and after that it is added drop wise to a solution containing Ca+2/Al+3. Microspheres which are
formed, kept in original solution for 24 hr. for internal gellification followed by filtration for
separation. The complete release is obtained at pH 6.4-7.2 but the drug will not release in acidic
pH16.
Wet Inversion Technique: In this method, a polymeric solution in acetic acid is added drop
wise into an aqueous solution of counter ion such as sodium tripolyphosphate through a small
sized nozzle. Microspheres are formed which are allowed to stand undisturbed for some time and
then cross linked with cross linking agents such as 5% ethylene glycol diglycidyl ether.
Microspheres obtained are then washed and freeze dried17.
Pan coating: In this method, the coating material is applied as solution in the coating pan. Warm
air is passed over the coated materials to remove the coating solvent18.
Complex Coacervation: CS (core cell) micro particles can also be prepared by complex
coacervations. Sodium alginate, sodium CMC and sodium polyacrylic acid can be used for
complex coacervation with CS (core cell) to form microspheres. By interionic interaction
between oppositely charged polymers solutions and KCl & CaCl2 solutions, these micro particles
are formed. The obtained capsules are hardened in the counter ion solution before washing19.
Hot Melt Microencapsulation: Here the melted polymer is mixed with solid particles of the
drug that have been sieved to less than 50 μm. The mixture is suspended in a non-miscible
solvent (like silicone oil) continuously stirred, and then heated to 5°C above the melting point of
the polymer. When the emulsion is stabilized, it is cooled until the polymer particles solidify.
The obtained microspheres are washed by decantation with petroleum ether. The necessary
objective for developing this method is to develop a microencapsulation method suitable for the
water labile polymers20.
Air suspension: In this process the dispersion of solid particles of core materials in a supporting
air stream is done followed by the spray coating of the air suspended particles21.
Solvent Removal: Solvent removal is a non-aqueous method of microencapsulation, mainly
preferred for water labile polymers. Solvent removal, drug is dissolved in a solution of the
selected polymer in a volatile organic solvent. This mixture is then suspended in silicone oil
containing Span 85 and volatile organic solvent. After added the polymer solution into silicone
oil, petroleum ether is mixed and stirred until solvent is obtained into the oil solution. The
resulting microspheres can then be dried in vacuum22.
Preparation of microspheres by glutaraldehyde cross linking: By aqueous acetic acid, a 2.5
%( w/w) chitosan solution are prepared. This dispersed phase is mixed to continuous phase (125
mL) making of light liquid paraffin and heavy liquid paraffin in the ratio of 1:1 containing 0.5%
(w/v) Span 85 to develop a water in oil (w/o) emulsion. Stirring is stirred at 2000 rpm using a 3blade propeller stirrer. A drop-by-drop solution of a measured quantity (2.5 mL each) of aqueous
glutaraldehyde (25% v/v) is mixed at 15, 30, 45, and 60 minutes. Stirring is stirred for 2.5 hours
and separated by filtration under vacuum and washed with petroleum ether (60 °C- 80 °C) and
then with distilled water to remove the liquid paraffin and glutaraldehyde. Then the microspheres
are dried in vacuum desiccators23.
Hydrogel Microspheres: Microspheres consist of gel-type polymers, such as alginate are
developed in a aqueous solution by dissolving the polymer, suspending the active material in the
solution and extruding by a precision technique, developing micro droplets which fall into a
hardening bath that is slowly stirred. The hardening bath usually takes calcium chloride solution,
whereby the divalent calcium ions crosslink the polymer developing gelled microspheres. The
hydrogel microspheres method involves an all-aqueous system and avoids residual solvents in
microspheres24.
Emulsion cross linking method: Emulsion cross linking method, drug is dispersed in aqueous
gelatin solution which is previously heated for 1 hr. at 40ᵒC. The solution is mixed drop wise to
liquid paraffin while stirring the solution at 1500 rpm for 10 min at 35ᵒC, results in w/o emulsion
stirring is done for 10 min at 15ᵒC. Thus the develop microspheres are washed three times with
acetone and isopropyl alcohol, then air dried and dissolved in 5mL of aqueous glutaraldehyde at
room temperature for 3 hr., for cross linking and then treated with 100mL of 10mm glycine
solution containing 0.1%w/v of tween 80 at 37 °C for 10 min to block unreacted glutaraldehyde.
An example for this emulsion cross linking technique is Gelatin microspheres25.
Preparation of microspheres by Tripolyphosphate: By 2.5% w/v concentration, chitosan
solution is prepared. Microspheres are developed by mixing the bubble-free dispersion of
chitosan by a disposable syringe (10 mL) onto a gently agitated (magnetic stirrer) 5% or 10%
w/v TPP solution. After 2 hrs, Chitosan microspheres separated, by filtration and washed with
distilled water, after that they were air dried26.
Preparation of Ethyl cellulose Microspheres: In acetone, a solution of Ethyl cellulose is mixed
to liquid paraffin containing emulgent (Span 85) while stirring at a speed of 1500 rpm. The
emulsion has been stirred for 5 to 6 hours at 25°C to 30°C. Subsequently, a proper amount of
petroleum ether has been mixed to the dispersion, filtered, and dried at ambient temperature. The
obtained microspheres washed with petroleum ether to remove traces of liquid paraffin27.
EVALUATION: –
Yield of Microspheres: The developed microspheres has been collected and weighed. By the
total amount of all non-volatile components, the measured weight are divided, which were used
for the development of the microspheres28.
% Yield = (Actual weight of product /Total weight of excipients and drug) x 100
Particle size, Shape and Morphology: All the develop microspheres has been considered with
respect to their size and shape using optical microscope fitted with an ocular micrometer and a
stage micrometer. The diameter of particle more than 100, optical microscope is being used for
measured microspheres. Scanning Electron photomicrographs of drug‐loaded microspheres
taken. A little amount of microspheres has been spread on gold stub. The, the stub obtained the
sample is placed in the Scanning electron microscopy (SEM)29.
Entrapment Efficiency: The capture efficiency of the microspheres can be measured by
allowing washed microspheres to lyse. The lysate is then subjected to measure the active
constituents as per monograph requirement. The percent encapsulation efficiency is calculated
using following equation30.
% Entrapment = Actual content/Theoretical content x 100.
Bulk density: By three tap method, bulk density can be measured. After filling the weighed
amount of microspheres in a graduated cylinder, the volume occupied by microspheres should be
measured31.
Surface topography by Scanning Electron: Scanning electron microscope of the microspheres
determines the surface morphology of the microspheres like their shape and size. The surface
morphology and structure are shown by scanning electron microscopy (SEM). The samples are
consisting of double side adhesive type by lightly sprinkling the microspheres powder which
already shucked to on aluminum stubs. Then, the stubs are kept into fine coat ion sputter for gold
coating. After gold coating samples are randomly scanned for determination of particle size and
surface morphology32.
Stability studies of Microsphere: The prepared microsphere is divided into 3 sets and stored at
4°C (refrigerator), room temperature and 40°C (thermostatic oven). After 15, 30 and 60 days
drug content of all the preparation measured spectrophotometrically33.
Scanning Electron Microscopy (SEM): Surface morphology is measured by the scanning
electron microsphere method. In this microcapsule has been placed directly on the scanning
electron microsphere slab with the help of double sided sticking tape and coated with gold film
under reduced pressure34 .
Swelling Index: Swelling index technique is being used for determination and characterization
of sodium alginate microspheres. Various types of solution like (distilled water, buffer solutions
of pH (1.2, 4.5 and 7.4) take and alginate microspheres (100 mg) are kept in a wire basket and
placed on the above solution. After that swelling is allow at 37°C and changes in weight
variation between initial weight of microspheres and weight due to swelling has been determined
by taking weight randomly and soaking with filter paper35.
In vitro wash-off test: A piece of rat stomach (1 cm x 1 cm) is tied onto a glass slide (3 inch x 1
inch) using a thread. Prepared slide of microsphere is hung onto one of the groves of the USP
tablet disintegrating test apparatus. The tissue specimen regular up and down movements in a
beaker obtaining the simulated gastric fluid by operated the disintegrating test apparatus. After
the end of every time period, the number of microsphere still covering on to the tissue is
calculate and there covering strength measured36.
In Vitro diffusion studies: By using in vitro nasal diffusion cell, in-vitro diffusion studies are
performed. The receptor chamber is filled with buffer maintained at 37±2°C. Accurately weighed
10 mg microspheres are spread on sheep nasal mucosa. After fixed time period 0.5 ml of
diffusion samples are withdrawn by a hypodermic syringe and replaced with the same quantity of
prepared fresh buffer solution to fixed a constant volume of the receptor compartment. The
samples are determined spectrophotometrically37.
Drug polymer interaction (FTIR) study: By Fourier transformed Infrared spectrophotometer,
IR spectroscopy can be showed. The drug and potassium bromide pellets are prepared by
compressing the powders at 20 psi for 10 min. On KBr‐press and the spectra are scanned in the
wave number range of 4000‐ 600cm-1
38
.
CONCLUSION
Mucoadhesive microspheres show as a selected carrier system for many pharmaceuticals. They
can be targeted to adhere to any mucosal tissue in the body surface. The control of drug releasing
properties has been the main aim of pharmaceutical research and development in the past two
decades. Mucoadhesive microspheres have been showed as promising candidate in delivery of
drugs to a particular surface in the body in sustained release manner, as they reached the drug to
a particular surface for longer period, the absorption of drug increased and hence, the
bioavailability of the drug get influenced. So we can say that in future also mucoadhesive
microspheres will play an important role in the development of new pharmaceuticals techniques
and material. Microsphere is the promising candidate for sustained and as a targeted drug
delivery in colon, GIT, liver, nasal, and ocular drug delivery etc. These are also performed as
diagnostic agent and for therapy of cancer too. Mucoadhesive drug delivery systems have
obtained popularity day by day in the pharma field and a current area of further research and
development.
REFERENCES:
1. Rajput G, Majumdar F Patel J, Thakor R & Rajgor NB; Stomach Specific mucoadhesive
microspheres as a controlled drug delivery system. Sys Rev Pharm 2010, 1(1): 70-78.
2. Portero, Osorio D.T., Alonso M.J., Lopez C.R.; Development of chitosan sponges for
buccal administration of insulin. Carbohydrate Polymers 2007, 68 (4): 617-625.
3. Parmar Harshad, Bakliwal Sunil, Gujarathi Nayan, Rane Bhushan, Pawar Sunil; Different
method of formulation and evaluation of mucoadhesive microspheres. International
Journal of Applied Biology and Pharmaceutical Technology 2010, 3(1): 1161.
4. Kataria Sahil, Middha Akansha, Sandhu Premjeet et al; Microsphere: A Review.
International Journal of Research in Pharmacy and Chemistry 2011, 1(4): 1184-1197.
5. Prausnitz et al, Patent no. 8197435, June 12, 2012.
6. Boder, Nicholas S, Patent no. 7691811, April 6, 2010.
7. Heavner et al, Patent no. 8603778, December 10, 2013.
8. Torobin, Leonard B, Patent no. 4743545, May 10, 1988.
9. Mathiowitz et al, Patent no. 6235313, May 22, 2001.
10. Unger, Evan C, Patent no. 6315981, November 13, 2001.
11. Unger, Evan C, Patent no. 5922304, July 13, 1999.
12. Mathowitz et al, Patent no. 6365187, April 2, 2002.
13. Milstein et al, Patent no. 5972387, October 26, 1999.
14. Shell et al, Patent no. 5186922, February 16, 1993.
15. Sachine.E. Bhandke; Formulation and Development of Repaglinide Microparticles by
Ionotropic Gelation Techniques. Indian J Pharm 2006, Edu Res.
16. Moy AC, Mathew ST, Mathapan R, Prasanth VV.; Microsphere-An Overview.
International Journal of Pharmaceutical and Biomedical Sciences 2011, 2 (2):332-338.
17. Mi FL, Shyu SS, Kuan CY, Lee ST, Lu KT, Jang SF; Chitosan polyelectrolyte
complexation for the preparation of gel beads and controlled release of anti-cancer drug,
Enzymatic hydrolysis of polymer. J Appl Polym Sci 1999, 74: 1868-79.
18. Chowdhary KPR, Srinivasa Rao Y; Mucoadhesion properties in relation to microspheres.
AAPS Pharm SciSN Tech 2003, 4: 320-325.
19. Soppimath K.S, T.M. Aminbhavi; Water transport and drug release study from cross
linked polyacrylamide grafted guar gum hydrogel microspheres for the controlled release
application. Eur J Pharma Biopharm 2002, 53: 87-89.
20. Nishioka Y, Kyotani S, Okamura M, Miyazaki M, Okazaki M, Ohnishi SY, Yamamoto
Y. Int.; Chitosan microspheres as a potential carrier of drugs. Chem Pharm Bull (Tokyo)
1990, 38: 2871– 2873.
21. Yellanki shiva kumar, Deb sambit kumar, Goranti sharada, Nerella Naveen kumar;
Formulation Development of Mucoadhesive Microcapsules of Metformin HCL Using
Natural and Synthetic Polymers and In vitro Characterization. Int J Pharm 2010, 2(2):
321-329.
22. Carino PG, Jacob JS, Chen CJ, Santos CA Hertzog BA, Mathiowitz E; Bioadhesive Drug
Delivery Systems-Fundamentals, Novel Approaches and Development. New York 1991,
2: 459.
23. Thanoo BC, Sunny MC, Jayakrishnan A; Cross-linked chitosan microspheres:
preparation and evaluation as a matrix for the controlled release of pharmaceuticals. J
Pharm Pharmacol 1992, 44: 283-286.
24. Lim ST, Martin GP, Berry DJ, Brown MB; Design and characterization of Bioadhesive
microspheres prepared by double emulsion solvent evaporation method. J Control
Release 2000, 66: 281-292.
25. Meena KP, Dangi JS, Samal PK, Namedo KP; Recent advances in microsphere
manufacturing technology. Int J Pharm Technol 2011, 3(1):854-855.
26. Warren S.J., I.W. Kellaway; The synthesis and in vitro characterization of the
mucoadhesion and swelling of poly (acrylic acid) hydrogels, Pharm Dev Technol 1998,
3(2): 199-208.
27. Gavini E, Sanna V, Juliano C, Benferoni MC, Giunchedi P; Pharmaceutical significance
of chitosan: A Review. AAPS Pharm Sci Tech 2002, 3: 1-7.
28. Alagusundaram M., Madhu Sudana Chetty C., Umashankari K.; Microspheres as a novel
drug delivery system- A Review. Int J ChemTech Res 2009, 1(3): 526-534.
29. Semalty A and Semalty M; Preparation and characterization of mucoadhesive
microspheres of ciprofloxacin hydrochloride. Indian drugs 2007, 44(5): 92-113.
30. Lim F, Moss RD; Microencapsulation of living cells and tissue, J Pharm Sci 1981, 70:
351-354.
31. Masareddy RS, Bolmal UB, Patil BR, Shah V; Metformin hcl loaded sodium alginate
floating microspheres prepared by ionotropic gelation technique. Indian J Novel Drug
Delivery 2011, 3(2):125-133.
32. Park K, Ch’ng HS, Robinson JR; Alternative approaches to oral-controlled drug delivery:
bioadhesive and in situ systems. In Recent advances in drug delivery system Anderson
JM and Kim. SW Eds. Plenum Press, New York 1984; 163.
33. Alferd Martin; Physical Pharmacy and physical chemical principals in pharmaceutical
sciences 1996, 4: 427-429.
34. G.T.Kulkarni, K. Gosthamarajan, B. Suresh; Stability testing of pharmaceutical products:
An overview. Indian J Pharm Edu 2004, 38,194-202-20.
35. Kalyankar T.M, Nalanda T. Rangari, Mubeena khan, Avinash hosmani, Arvind Sonwane;
Formulation and Evaluation of Mucoadhesive Pioglitazone HCL Microspheres. Int J
Pharm world Res 2010, 1(3):1-14.
36. Lehr CM, Bowstra JA, Tukker JJ, Junginer HE; In vitro evaluation of mucoadhesive
properties of chitosan and some other polymers. J Control Release 1990, 13: 51-62.
37. Pisal S, Shelke V, Mahadik K, Kadam S.; Effect of organogel components on in vitro
nasal delivery of propranolol hydrochloride, AAPS Pharm Sci Tech 2004, 5: 63.
38. Lim F, Moss RD. Microencapsulation of living cells and tissues. J Pharm Sci 1981; 70:
351-354.