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DEFINATION Microspheres can be defined as solid, approximately spherical particles ranging in size from 1 to 1000 μ m. Made up of polymeric, waxy, or other protective materials such as starches, gums, proteins, fats, and waxes and used as drug carrier matrices for drug delivery. Microcapsules : micrometric reservoir systems Microspheres : micrometric matrix systems. Natural polymer can also be used: Albumin Gelatin 3

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4 . Drug Core Polymer Coat = Polymer Matrix } = Entrapped Drug MICROCAPSULES MICROSPHERES Microspheres are essentially spherical in shape, whereas, microcapsules may be spherical or non-spherical in shape. Microparticles , either microcapsules or microspheres, as the same: ‘microcapsules’.

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Alternative Terms used in place of microspheres: Microbeads Beads 5


They facilitate accurate delivery of small quantities of potent drug and reduced concentration of drug at site other than the target organ or tissue. They provide protection for unstable drug before and after administration, prior to their availability at the site of action. They provide the ability to manipulate the in vivo action of the drug , pharmacokinetic profile, tissue distribution and cellular interaction of the drug. They enable controlled release of drug. Ex: narcotic, antagonist, steroid hormones ADVANTAGE OF MICROSPHERES 6

Types of microspheres:

Types of microspheres Microcapsule: consisting of an encapsulated core particle. Entrapped substance completely surrounded by a distinct capsule wall. Micro-matrix : Consisting of homogenous dispersion of active ingredient in particle. 7 Microcapsule Micromatrix Types of Microspheres

Polymer Used For Microspheres Preparations:

Polymer Used For Microspheres Preparations 8

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Prerequisites for Ideal Microparticulate Carriers :

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 10

Parameters That can be satisfactorily Controlled:

Taste and odour masking Conversion of oil and other liquids, facilitating ease of handling Protection of the drug from the environment Delay of volatilisation 11 Parameters That can be satisfactorily Controlled

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Freedom from incompatibilities between drug and excipients, especially the buffers Improvement of flow properties Dispersion of water insoluble substance in aqueous media Production of sustained release, controlled release and targeted medication 12


METHODS OF PREPARATIONS 13 Solvent evaporation method Single emulsion technique Double emulsion technique Coacervation phase separation method Spray drying and spray congealing method Polymerization method

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A. Single Emulsion Technique cross linking Heat denaturation (by adding dispersion To heated oil) Chemical crosslinking ( butanol,HCHO,Glutaraldehyde ) 14 14

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Microspheres in org.phase Microspheres in org.phase Centrifugation, washing, & separation Microspheres 15

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B. Double Emulsion Technique Aqueous solution of polymer dispersion in oil/organic phase, vigorous homogenisation ( sonication) Primary emulsion(w/o) addition of aqueous solution of PVA W/O/W multiple emulsion Addition of large aqu . phase Microspheres in solution 16

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Separation, washing, drying MICROSPHERES 17

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18 C)Polymerization A)Normal Polymerization Normal Polymerization is done by bulk, suspension, precipitation, emulsion and polymerization process. Bulk polymerization:

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19 B)Suspension polymerization Monomer Bioactive material Initiator Dispersion in water and stebilizer Droplet Vigorous Aggitation Polymerization by Heat Hardened microspheres Separation & Drying MICROSP HERES

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20 c)Emulsion Polymerization Monomer/ Aq.Solution of NaOH , Bioactive material Initiator, Surfactant , Stabilizer Dispersion with vigorous stirring Micellar sol. Of Polymer in aqueous medium Polymarization Microspheres formation MICROSPHERES

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21 D)Phase Separation Coacervation Aq./organic solution of polymer Drug dispersed or dissolved in the polymer solution Phase sepration by salt addition, non solvent addition add. Incompatible polymer,etc Polymer rich globules Hardening Microspheres in aqu ./organic phase separation/drying MICROSPHERES

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22 E)Spray Drying 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

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23 F)Solvent Extraction 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

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24 G)Precipitation Method An emulsion is formed, which consists of polar droplets dispersed in a non-polar medium. Solvent may be removed from the droplets by the used of a co-solvent. The resulting increase in the polymer-drug concentration causes a precipitation forming a suspension of microspheres.

Rout of administration:

Rout of administration Oral delivery Parenteral delivery 25

Mechanisms of drug release:

Mechanisms of drug release Degradation controlled monolithic system. Diffusion controlled monolithic system. Diffusion controlled reservoir system. Erodible poly agent system. 26

Analysis of microspheres:

Analysis of microspheres Electron Microscopy, Scanning Electron Microscopy and Scanning Tunneling Microscopy – Surface Characterization of Microspheres Fourier Transform Raman Spectroscopy or X-ray Photoelectron Spectroscopy –to Determine If Any Contaminants Are Present Surface Charge Analysis Using Micro- electropshoresis – Interaction of Microspheres Within the Body 27

Physicochemical evaluation & characterization:

Physicochemical evaluation & characterization 28

Particle size & shape:

Particle size & shape 29 The most widely used procedures to visualize micro particles are conventional light microscopy ( LM) and scanning electron microscopy (SEM).

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LM provides a control over coating parameters in case of double walled microspheres. The microspheres structures can be visualized before and after coating and the change can be measured microscopically . SEM allows investigations of the microspheres surfaces and after particles are cross-sectioned, it can also be used for the investigation of double walled systems . Conflocal fluorescence microscopy is used for the structure characterization of multiple walled microspheres. Laser light scattering and multi size coulter counter other than instrumental methods, which can be used for the characterization of size, shape and morphology of the microspheres. 30

Capture efficiency:

Capture efficiency 31

Release studies :

Release studies It is done by using rotating paddle apparatus and Dialysis method 32 Angle of repose Determine wetting properties of Microparticulate carriers

Electron spectroscopy for chemical analysis:

Electron spectroscopy for chemical analysis The surface chemistry of the microspheres can be determined using the electron spectroscopy for chemical analysis (ESCA). ESCA provides a means for the determination of the atomic composition of the surface . The spectra obtained using ECSA can be used to determine the surfacial degradation of the biodegradable microspheres . 33

Attenuated total reflectance ft-ir:

Attenuated total reflectance ft-ir Used to determine the degradation of the polymeric matrix of the carrier system. Surface of microspheres are investigated by ATR. ATR-FT-IR provides surface composition of microspheres. 34

Density determination :

Density determination Can be determined by using MULTI VOLUME PYCHNOMETER 35

Isoelectric point:

Isoelectric point The micro electrophoresis is an apparatus used to measure the electrophoretic mobility of microspheres from which the isoelectric point can be determined. Mean velocity at different Ph values ranging from 3-10 is calculated by measuring the time of particle movement over a distance of 1 mm. using this data the electrical mobility of the particle can be determined. The electrophoretic mobility can be related to surface contained charge, ionisable behaviour or ion absorption nature of the microspheres. 36

Surface carboxylic acid:

Surface carboxylic acid Measured by using RADIOACTIVE GLYCINE 37 EDAC

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RADIOACTIVITY is then measured by using LIQUID SCINTILLATION COUNTER Carboxylic acid residue can be find out 38

In-vitro methods:

In-vitro methods 39

Interfacial diffusion system:

Interfacial diffusion system 40 Before use, the aqueous phase and 1-octanol were saturated with each other. Samples were withdrawn and returned to compartment A with a syringe .

Modified kc-cell:

Modified kc -cell Consist of KC-Cell containing distilled water (50ml) at 37 0 C as dissolution medium TMDDS was placed in a glass tube fitted with a 10# sieve at the bottom which reciprocate in the medium at 30 strokes per min. 41

In-vivo methods:

In-vivo methods Animal used: dog, rabbits, rat, cat, hamster, pigs, and sheep RAT: The oesophagus is ligated to prevent absorption pathways other than oral mucosa At different time intervals, the blood is withdrawn and analysed 42

Ivivc correlation:

Ivivc correlation


applications MICROSPHERES IN VACCINE DELIVERY. Eg ; Diphtheria toxoid , Tetanus toxoid. TARGETED DRUG DELIVERY. Eg ; ocular, eye (cornea). etc CONTROLLED RELEASE. Eg ; GI tumors, Bone tumors. CHEMOEMBOLIZATION. IMMUNO MICROSPHERES 44

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45 Thank you……

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