Microspheres are spherical particles between 50nm and 2mm that contain a core substance. They are made of biodegradable natural or synthetic polymers and ideally have a size under 200 micrometers. Synthetic polymers used include PMMA and lactides/glycolides, while proteins and carbohydrates like albumin, gelatin, starch and chitosan are natural options. Microspheres are prepared using emulsion techniques and characterized based on particle size, shape, capture efficiency and stability over time and conditions. Potential applications include use as antigen carriers for vaccines and delivery of drugs or other substances.
Content:
Introduction
Ideal Properties
Advantages
Limitations
Types of Microsphere
Method for Preparation
Polymer Used for Preparation
Release of Drug from Microsphere
Application
An overview of Microspheres including Advantages, Types, Method of preparation, Materials used in preparations, Characterization or Evaluation and Applications.
Content:
Introduction
Ideal Properties
Advantages
Limitations
Types of Microsphere
Method for Preparation
Polymer Used for Preparation
Release of Drug from Microsphere
Application
An overview of Microspheres including Advantages, Types, Method of preparation, Materials used in preparations, Characterization or Evaluation and Applications.
Microparticles or microspheres are defined as small, insoluble, free flowing spherical particles consisting of a polymer matrix and drug. and sized from about 50 nm to about 2 mm. The term nanospheres is often applied to the smaller spheres (sized 10 to 500 nm) to distinguish them from larger microspheres.
Microparticles or microspheres are defined as small, insoluble, free flowing spherical particles consisting of a polymer matrix and drug. and sized from about 50 nm to about 2 mm. The term nanospheres is often applied to the smaller spheres (sized 10 to 500 nm) to distinguish them from larger microspheres.
The objective of the current investigation is to formulate sustained release microspheres, containing Metformin hydrochloride and Glipizide as model drugs. Eudragit RSPO, Eudragit RLPO, Ethyl cellulose and Hydroxy propyl methyl cellulose, polymers of different permeability characteristics were used in combination to prepare different microspheres. Metformin and Glipizide both are type II antidiabetic agents when administered together shows synergetic effect in their action. Microspheres were prepared by emulsion solvent evaporation method with different stabilizer concentration and at different speeds of emulsification while maintaining constant amounts of Metformin and Glipizide. Drug excipients compatibility study was performed prior to formulation development and only compatible excipients were used in the fabrication of microspheres. Prepared microsphere formulations were characterized by percentage yield, particle size analysis, entrapment efficiency, in-vitro release behavior, FTIR, differential scanning colorimetry (DSC) and scanning electron microscopy (SEM). SEM studies showed that the microspheres were spherical with rough surface morphology. The drug loaded microspheres showed 29-90% entrapment capacity for Metformin and Glipizide. The in-vitro release profile showed a slow and steady release pattern for both Metformin and Glipizide. A 100% Metformin was releases within a period of 12 hrs while only 30% Glipizide was released during this time. The Metformin HCl release was found to be best fitted with Higuchi and Zero order and for Glipizide best fitted with zero order and first order respectively in single and combined polymeric loaded microspheres. DSC results indicated that the physical state of the drug was changed upon fabrication. As a result of these experiments, it was conclude that, novel sustained release oral microspheres comprising a combination of Metformin and Glipizide were successfully prepared using ethyl cellulose, HPMC 15CPS, Eudragit RSPO and Eudragit RLPO as the polymer and using emulsion solvent evaporation technique.
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Microspheres are spherical & free flowing particles ranging in average particle size from 1 to 50 microns which consist of proteins or synthetic polymers. Some of the problems of overcome by producing control drug delivery system which enhances the therapeutic efficacy of a given drug. One such approach is using microspheres as carriers for drugs. The target site drug deliver with Specificity & maintain the concentration at site of interest without untoward effects. It will find the central place in novel drug delivery. Drugs can be targeted to specific sites in the body using microspheres. Degree of targeting can be achieved by localization of the drug to a specific area in body (for example in lungs), to a particular group of cells and even to the intracellular structures. The rate of drug release from the microspheres dictates their therapeutic action.
Nanoparticles are sub-nanosized colloidal structures composed of synthetic or semi synthetic polymers.
The drug is dissolved, entrapped, encapsulated or attached to a nanoparticle matrix.
MANUFACTURING EQUIPMENTS,EVALUATION &STABILITY ASPECTS OF MICROCAPSULESagar Savale
Microencapsulation is describe as a process of enclosing micron sized particles of solid or droplets of liquids or gases in an inert shell, which in turn isolates & protects from environment. The product is obtained by this process is called micro-particles, micro capsules, micro spheres.
Cell immobilization is the process of fixing intact cells onto specific regions in a device or material without losing their biological function. Cells can be immobilized through physical adsorption, encapsulation, entrapment, and self-aggregation.
Nanoparticles are defined as particulate dispersions or solid particles drug
carrier that may or may not be biodegradable. Several techniques are used for preparation of
nanoparticles like Solvent Evaporation, Double Emulsification method, Emulsions - Diffusion
Method, Nanoprecipitation, Coacervation method, Salting Out Method, Dialysis and
Supercritical fluid technology. Nanoparticles are subjected to several evaluation parameters
such as yield of nanoparticles, Drug Content / Surface entrapment / Drug entrapment, Particle
Size and Zeta Potential , Surface Morphology, Polydispersity index, In-vitro release Study,
Kinetic Study, Stability of nanoparticles
A note on Microsperes , general introduction and method of preparationsNEELAMSOMANI4
This presentation is related to Microspheres. Microspheres as a part of novel drug delivery system relevant to Pharmaceutics. The general introductions and methodology is described that will be helpful to all pharmacy students .
3. The 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 micrometer.
Polymers of both natural and synthetic
origin can be used.
5. • Synthetic non-biodegradable materials used are
PMMA, Acrolein etc and biodegradable
materials used are Lactides and glycolides and
their copolymers.
• Proteins like albumins, gelatin and
carbohydrates like starch, glucose, chitosan
etc are also used.
6. Prerequisites for Ideal Micro particulate carriers:
o Longer duration of action
o Increase of Therapeutic efficiency.
o Biocompatibility
o Sterilizability
o Relative Stability
o Water solubility or dispersability
7. Methods of Preparation
Preparation
methods
Emulsion
Polymerization
techniques
Single Double Normal and
Emulsion Emulsion Interfacial
8. Drug Release Kinetics
Liberation due to Polymer erosion
Self diffusion through the pore.
Release from the surface of the polymer
Pulsed delivery initiated by application
of an oscillating or sonic field
11. Preparation of Microspheres
Aq. Soln of 8% w/v acrolein 0.5%
sodium bisulphite polyglutaraldehyde
conjugate
pH adjusted to 10.5
Dialysis and centrifugation
Microspheres
12. Characterization
Particle Size and shape:
• The most widely used procedures are conventional
light microscopy and scanning electron microscopy.
• Confocal laser scanning microscopy is a non
destructive visualization technique.
• Confocal fluorescence microscopy is used for
Structural characterization.
13. Capture Efficiency
It
is the percent entrapment determined by allowing
washed microspheres to lyse.
The lysate is subjected to the determination of
active constituents.
% entrapment = Actual content
________________ * 100
Theoretical content
14. Density determination is done by using a
multivolume pychnometer.
Micro electrophoresis is an apparatus used to
measure electrophoretic mobility
of microspheres.
Surface associated amino acid residue is
determined by C – Acetic acid conjugate.
The accuracy depends on the time
allowed for conjugation.
19. Efficient transport across microvascular
barrier can be achieved by:
Magnetic dragging of the magnetic microparticles
directly through endothelium and basement
membrane.
Facilitated transport of specific ligand drug
conjugates or coated microspheres across endothelium
as a result of ligand binding to luminal surface antigen
or receptors.
Transient regional opening of endothelium function
combined with vascular infusion of drug carrier that
becomes sequestered in the extracellular complex.