This document summarizes microspheres, which are spherical particles smaller than 200 microns made of biodegradable polymers or proteins. Microspheres can be used to deliver drugs in a controlled manner and provide benefits like taste masking and protection from environmental degradation. Common methods for preparing microspheres include single/double emulsion and polymerization techniques. Microspheres find applications in drug delivery, vaccines, and imaging and are characterized based on properties like size, morphology, drug release kinetics, and thermal behavior. Recent research involves development of targeted and sustained release microsphere formulations.
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Microspheres
1. A Presentation by
Sumit kondal & Shubham Thakur
Under the guidance of
Mr. Pankaj Sharma (Dept. of
Pharmaceutics)
2. • INTRODUCTION
• ADVANTAGES
• POLYMERS USED IN MICROSPHERES
• PREREQUISITES FOR MICROCAPSULE CARRIER
• METHODS OF PREPRATION
• APPLICATIONS
• RECENT ADVANCEMENT
• CHARACTERIZATION OF MICROSPHERES
3. Microspheres are characteristically free flowing
powders consisting of proteins or synthetic polymers
which are biodegradable in nature and ideally having a
particle size less than 200 μm.
Spherical particle size
vary from 50nm to 2mm
microcapsule micromatrix
4. Potential use of microspheres in the pharmaceutical industry
• Taste and odor masking
• Conversion of oils and other liquids to solids for ease of handling
• Protection of drugs against the environment (moisture, light etc.)
• Separation of incompatible materials (other drugs or excipients)
• Improvement of flow of powders
• Aid in dispersion of water-insoluble substances in aqueous media,
• Production of SR, CR, and targeted medications.
6. Prerequisites for Ideal
Microparticulate Carriers
• Longer duration of action
• Control of content release
• Increase of therapeutic efficacy
• Protection of drug
• Reduction of toxicity
• Biocompatibility
• Sterilizability
• Relative stability
• Water solubility or dispersibility
• Bioresorbability
• Targetability
• Polyvalent
7. MICROSPHERE
MANUFACTURE
Most important physicochemical characteristics
that may be controlled in microsphere
manufacture are:
Particle size and distribution
Polymer molecular weight
Ratio of drug to polymer
Total mass of drug and polymer
8. GENERAL METHODS OF
PREPARATION
• Single Emulsion techniques
• Double emulsion techniques
• Polymerization techniques
- Normal polymerization
- Interfacial polymerization
• Coacervation phase separation techniques
• Spray drying and spray congealing
• Solvent extraction
9. Aq.Solution/suspension of polymer
Microspheres in organic phase Microspheres in organic phase
Dispersion in organic phase
(Oil/Chloroform)
Microspheres
Stirring , sonication
Heat denaturation
Chemical cross linking
(Glutaraldehyde/Formaldehyde/ Butanol)
Centrifugation seperation
10. Aq.Solution of protein/polymer
First emulsion (W/O)
Multiple emulsion
Microspheres in solution
microspheres
Dispersion in oil/organic phase
Homogenization
Addition of aq. Solution of PVA
Addition to large aq. Phase
Denaturation/hardening
Separation, Washing, Drying
11. First, the polymer is dissolved in acetone, then a
phospholipid mixture (e.g., Epikuron'") and
benzyl benzoate are added to this solution.
The resulting organic solution is poured into an
aqueous phase containing a surfactant (e.g.,
poloxamer 188) under moderate stirring.
Acetone diffuses immediately into the aqueous
phase, inducing the deposition and the
precipitation of the polymer around the oily
droplets.
Once the microcapsules are formed, acetone is eliminated under
reduced pressure.
Drugs intended to be encapsulated by this method must have a high
solubility in the organic-oily phase, otherwise they diffuse from the oily
solution and precipitate in the aqueous medium during particle
formation.
12. When two reactive monomers are dissolved in immiscible
solvents,the monomers diffuse to the oil water interface where
they react to form a polymeric membrane. Drug is incorporated
either by being dissolved in the polymerization medium or by
adsorption onto the nanoparticles after polymerization
completed. The nanoparticle suspension is then purified to
remove various stabilizers and surfactants employed for
polymerization by ultracentrifugation and resuspending the
particles in an isotonic surfactant-free medium.
This technique has been reported for making
polybutylcyanoacrylate or poly (alkylcyanoacrylate)
nanoparticles.
13. Aqueous/Organic Solution of polymer
Drug dispersed or dissolved in polymer
solution
Polymer rich globules
Microspheres in aq./organic phase
Microspheres
Drug
Phase seperation induced by various means
Hardening
Separation, Washing, Drying
14. Polymer dissolve in volatile organic solvent (acetone,
dichloromethane)
Drug dispersed in polymer solution under high speed
Homogenization
Atomized in a stream of hot air
Due to solvent evaporation small droplet or fine mist form
Leads to formation of Microspheres
Microspheres separated from hot air by cyclone separator, Trace
of solvent are removed by vacuum drying
15. Drug is dispersed in organic solvent (water miscible organic
solvent such as Isopropanol) Polymer in organic solvent
Organic phase is removed by extraction with water . (This
process decreasing hardening time for microspheres)
Hardened microspheres
16. • Microencapsulated products currently on the market, such as
aspirin, theophylline & its derivatives, vitamins, pancrelipase,
antihypertensive, potassium chloride, progesterone, and
contraceptive hormone combinations.
• Microencapsulated KCl is used to prevent gastrointestinal
complications associated with potassium chloride.
• Microspheres have also found potential applications as injection,
or inhalation products.
• Most encapsulation processes are expensive and require
significant capital investment for equipment.
• An additional expense is due to the fact that most
microencapsulation processes are patent protected.
17. • Microcapsules are also extensively used as diagnostics, e.G ,
temperature sensitive microcapsules for thermographic detection of
tumors.
• In the biotechnology industry microencapsulated microbial cells are
being used for the production of recombinant proteins and peptides.
• Encapsulation of microbial cells can also increase the cell-loading
capacity and the rate of production in bioreactors.
• A feline breast tumor line, which was difficult to grow in conventional
culture, has been successfully grown in microcapsules.
• Microencapsulated activated charcoal has been used for
hemoperfusion.
18. SWINE FLU INFLUENZA DNA VACCINE
ENCAPSULATED IN PLGA MICROSPHERE
DNA vaccine against Swine flu influenza encapsulated
in poly(D,L)lactic co glycolic acid(PLGA) microspheres.
Prepared by Emulsion evaporation method using
PLGA as biodegradable matrix formic polymer. PLGA
microspheres containing DNA vaccine can be used to
achieved prolonged released of plasmid DNA.
19. s-PLLA/IBUPROFIN MICROSPHERES(2010)
These are star shaped poly(L- lactide)loaded
ibuprofen (s-PLLA/IBU) microspheres. Prepared
using Solvent evaporation method IBU could
combine with s-PLLA well and part ofPLLA were
degraded after releasing.The drug encapsulating
efficiency of s-PLLA/IBUmicrospheres is high and
release of ibuprofen from microspheres is slow
and effective.
20. • Vaccine delivery – Improved antigenecity, Ag release,
• Stabilization of Ag
• Drug targeting
◦ Ocular: gelation with increased residence time
◦ Intranasal: protein and peptide delivery
◦ Oral
• Magnetic microspheres
• Immunomicrospheres
• Chemoembolization
• Imaging
• Microsponges
• Surface modified microspheres
21. • YIELD VALUES AND LOADING EFFICIENCY:
Yield value = 100 x Obtained wgt. Of microspheres
Theoretical wgt to be prepared
Loading = 100 x actual amt. of drug obtained by
extraction effeciency theoretical wgt. of drug added in
preparation
• MICROSPHERE MORPHOLOGY:In this the prepared
loaded microsphere is analyzed by scanning electronic
microscope(SEM)after palladium/gold coating of the
samples on an aluminium strip.
22. • MICROSPHERE SIZE DISTRIBUTION: Mean size is
determined by methods like Laser diffractometry
method.
• BULK DENSITY MEASUREMENT: By dipping method
• MEASUREMENT OF GLASS TRANSITION TEMP
(Tg) BY DSC: Tg is measured by DSC for the blank
(unloaded) and the prepared loaded microspheres.
• SURFACE CHEMISTRY BY ELECTRON
SPECTROSCOPY: Done for chemical analysis Provides
means of determination of atomic composition of
the surface.
23. • RELEASE STUDY: Carried out in phosphate saline buffer
Ph7.4. Two methods-
1. Rotating paddle dissolution appratus.
2. Dialysis method.
• ISOELECTRIC POINT: Microelectrophoresis apparatus is
used to measure electrophoretic mobility of
microspheres from which isoelectric point can be
determined.
• DEGREE OF HYDRATION: Measured to evaluate water
uptake by the system as a first step in biodegradation.
