Microspheres ppt

MOLECULAR PHARMACEUTICS
(MICROSPHERES)
Presented by : Gutte Vaishali Pundlik
Roll no : 05
M pharm (Pharmaceutics)
Under Guidance Of : Proff.Shraddha Tiwari Mam
DAYANAND COLLEGE OF PHARMACY, LATUR
July 15, 2022

CONTENT :
 Introduction of microspheres
 Advantages
 Disadvantages
 Polymers used in microspheres
 Types
 Preparation
 Evaluation
 Reference

INTRODUCTION:
Microspheres:
Microspheres are small spherical particles, with diameter 1 μm to 1000 μm. They are
spherical free flowing particles consisting of proteins or synthetic polymers which are
biodegradable in nature.

ADVANTAGES:
 Improve bioavailability
 Provide constant and prolonged therapeutic effect.
 Provide constant drug concentration in blood .
 Decrease dose and toxicity.
 Protect the drug from enzymatic and photolytic cleavage so it is best for drug
delivery of protein.
 Reduce the dosing frequency and thereby improve the patient compliance

DISADVANTAGES:
 The cost is more.
 Reproducibility is less.
 Process conditions like change in temperature, pH, solvent addition, and
evaporation/agitation may influence the stability of core particles.
 Degradation of product due to heat, hydrolysis, oxidation, solar radiation or
biological agents.

POLYMERS USED :
1) Synthetic polymers:
a) Non – biodegradable: Poly methyl methacrylate (PMMA),Acrolein,Glycidyl
methacrylate,Epoxy polymers.
b) Biodegradable: Lactides,Glycolides,poly alkyl cyanoacrylates,poly anhydrides
2) Natural polymers:
a) Proteins : Albumin,Gelatin, Collagen
b) Carbohydrates: Agarose,Carrageenan,Chitosan,Starch
c) Chemically modified carbohydrates : Poly dextran,Poly starch
DAYANAND COLLEGE OF PHARMACY,LATUR

TYPES OF MICROSPHERES:
1. Bioadhesive microspheres
2. Floating microspheres
3. Radioactive microspheres
4. Magnetic microspheres
5. Polymeric microspheres
i)Biodegradable polymeric microspheres
ii)Synthetic polymeric microspheres

1.Bioadhesive Microspheres :
Adhesion of drug delivery device to the mucosal membrane such as buccal,
ocular, rectal , nasal etc. Can be termed as bio adhesion. These kinds of
microspheres exhibit a prolonged residence time at the site of application and
causes intimate contact with the absorption site and produces better therapeutic
2.Floating Microspheres :
In floating types the bulk density is less than the gastric fluid and so remains
buoyant in stomach without affecting gastric emptying rate. The drug is released
slowly at the desired rate, and the system is found to be floating on gastric
content and increases gastric residence and increases fluctuation in plasma
concentration. Moreover it also reduces chances of dose dumping. It produces
prolonged therapeutic effect and therefore reduces dosing frequencies.

3. Radioactive Microspheres :
Radioactive microspheres Deliver high radiation dose to targeted site without
damaging the normal surrounding tissues.Diagnostic: Applicabe for cancer
therapies .ex., in case of Liver , spleen .Radioactive microspheres are alpha
emitters,beta emitters and gamma emitters.
4 .Magnetic Microspheres :
Magnetic microspheres Localize the drug to the disease site. In this larger
amount of freely circulating drug can be replaced by smaller amount of
magnetically targeted drug. Magnetic carriers receive magnetic responses to a
magnetic field from incorporated materials that are used for magnetic
microspheres are chitosan,dextran etc. These magnetic microspheres are used to
deliver chemotherapeutic agents to liver tumor Drugs like proteins and peptides
can also be targeted through this system.

5.Polymeric Microspheres :
The various types of polymers are used for preparation of microspheres e.g:-
Albumin microspheres , Gelatin microspheres , Starch microspheres , Dextran
microspheres , Carrageenan
Polymeric microspheres are classified as :
a.Biodegradablee polymeric microspheres:-
Natural polymers such as starch are used with the concept that they are
biodegradable, biocompatible,and also bioadhesive in nature. Biodegradable
polymers prolongs the residence time when contact with the mucous membrane
due to its high degree of swelling property with aqueous medium. The rate and
extent of drug release is controlled by concentration of polymers.
b. Synthetic polymeric microspheres:-Widely used in clinical applications. ,
Alginate microspheres .

METHODS OF PREPARATION:
1. Solvent evaporation method
2. Emulsion cross linking method
3. coacervation/ phase separation method
4. spray drying method
5. Emulsion – solvent diffusion method
6. Multiple emulsion method
7. Ionic gelation method

1.SOLVENT EVAPORATION METHOD :
Core material
↓Dissolved or dispersed
coating polymer solution
↓Agitation
core material disperse in liquid manufacturing vehicle paste
↓Heating,if needs
evaporation of polymer solvent
↓
microspheres

2.EMULSION CROSS LINKING METHOD:
Aq. Solution / suspension polymer
↓
Dispersion in organic phase oil
↓ 1. Heat denaturation
2. by chemical cross linking
microspheres in organic phase
↓ centrifugation,wash, separation
microspheres

3.PHASE SEPARATION COACERVATION
METHOD:
Aq. / organic solution of polymer
↓ Add drug
Drug dispersed or dissolved in the polymer solution
↓phase seperation induced by different
means
Polymer rich globules
↓solidify
Microspheres in aq./ organic phase
↓separate,wash,dry
Microspheres.

4.SPRAY DRYING/CONGEALING METHOD:
Polymer dissolved in volatile organic solvent (acetone)
↓
Drug dispersed in polymer solution under high speed homogenization
↓
Atomized in a stream of hot air
↓
Solvent evaporation of small droplets leads to formation of microspheres
↓
Microspheres separated from hot air by colone separator and trace of solvent are
removed by vaccum drying.

5.EMULSION SOLVENT DIFFUSION
METHOD:
Drug + Lipophilic surfactant
↓
Dissolve in water miscible solvent
↓
Add into aqueous surfactant
↓
Stirring
↓
High pressure homogenization
↓
Diffusion of the solvent
↓
Formation of microspheres

6.MULTIPLE EMULSION METHOD:
Polymer in aq. Solution + drug
↓Homogenization / sonication
Disperse in organic phase
↓
Primary emulsion
↓Addition of aq. Solution of PVA
Multiple emulsion
↓Addition to large aq. Phase
Microspheres in solution
↓separation,wash,dry
Microspheres

7.IONIC GELATION METHOD:
Sod. Alginate + Water
↓stirred+drug + cal.carbonate
Cal.chloride + 2 % Glacial acetic acid
↓
The gel microspheres formed in solution
↓stirred for 30 min at room temperature
Microspheres are collected,washed,dried

EVALUATION:
 Particle shape and size
 Degradation behaviour
 Angle of repose
 Bulk density
 Tapped density
 Drug entrapment efficiency
 Swelling index
 In vitro methods
 Adhesion property

 Particle size and shape:
The most widely used procedures to visualize microparticles are conventional
light microscopy (LM) and scanning electron microscopy (SEM).
 Degradation behavior:
The surface chemistry of the microspheres can be determined using the electron
spectroscopy for chemical analysis (ESCA).
 Angle of repose:
The powder mass was allowed to flow through the funnel orifice kept vertically
to a plane paper kept on the horizontal surface, giving a heap angle of powder on
paper. The angle of repose was calculated by the following equation
tan θ =h/r
Where, h & r are the height and radius of the powder cone.

 Bulk density:
Bulk density was obtained by dividing the mass of powder by the bulk volume in
cm3.
It was calculated by using equation:
Bulk density = mass of microspheres / bulk volume
 Tapped density:
It is the ratio of total mass of the powder to the tapped volume of the powder.
It is expressed in g/ml and is given by :
Tapped density = mass of microspheres /Tapped volume..
 Drug entrapment efficiency:
It is the percentage of drug that is successfully entrapped with in microspheres .
Drug entrapment efficiency can be calculated using following equation,
% Entrapment = Actual content / Theoretical content x 100

 Swelling index :
It is conducted in a phosphate buffer of pH 6.8.Their diameter is measured
periodically by using laser particle size distribution analyzer until they were
decreased by erosion and dissolution.
Swelling index= (mass of swollen microspheres – mass of dry microspheres/mass
of dried microspheres) 100
 8) In vitro methods:
Release studies for different type of microspheres are carried out by using phosphate
buffer pH 7.4, mostly by rotating paddle apparatus. Agitated with 100 rpm, samples
were collected at specific time intervals and replaced by same amount and analyzed.
 9) Adhesion property:
Freshly cut piece of pig intestine is used (5 cm long),clean and wash it with isotonic
saline solution.

CONCLUSION:
 Microspheres are having wide applications in drug delivery systems. Most
important are the targeted drug delivery ,Controlled and sustained drug
delivery .By combining various strategies, microspheres will find central place
in novel drug delivery mainly particularly in cell sorting, diagnostics and
Genetic engineering.

REFERENCES:
 PV .A TEXT BOOK OF MOLECULAR PHARMACEUTICS.PAGE NO. 85 - 97
 Https://www.slideshare.net/ Sowjanyareddy 14019338.
 REVIEW ARTICLE FROM INTERNATIONAL JOURNAL OF CURRENT
PHARMACEUTICAL RESEARCH, BY KUMAR DAS,ABDUL BAQEE AHMED,DIPANKAR
SAHA.

Microspheres ppt

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