o Oral route of administration.
o Conventional drug delivery system frequent administration.
o Significant fluctuation in drug levels.
o Novel drug delivery system.
o Sustained and controlled release .
4. Definition of microspheres:
• Micro-particles or microspheres small, insoluble, free flowing spherical
• Size -10 to 1000 µm.
• Ideally, completely spherical and homogeneous in size.
5. • Polymers or proteins biodegradable .
• Drug dispersed or dissolved controlled release of the drug.
• Prolonged release & targeting.
6. Types of Microspheres:
• Microcapsule: An encapsulated core particle .
• Micromatrix (Mcrospheres): Homogenous dispersion.
Types of Microspheres:
• Sustained and Controlled release .
• Patient compliance is increased.
• Toxic effect is less.
• Targeting the tissue is possible.
• Improve bioavailability.
• They enable controlled release of drug.
Ex: narcotic, antagonist, steroid hormones.
• Protect the drug from enzymatic and photolytic cleavage so it is best for drug delivery of
• The cost is more.
• Reproducibility is less.
• Stability may affected by process conditions.
• Degradation of product.
• Intended mainly for parenteral route which causes pain.
• Polymer may produce toxic effects
9. Polymers used in the Microsphere preparation:
• PMMA(Poly methyl Methacrylate).
• Epoxy polymers
• Glycidyl methacrylate
• Lactides and Glycolides copolymers
• Polyalkyl cyanoacrylates
14. B. Double Emulsion Technique:
Aqueous solution of polymer & drug
dispersion in oil/organic phase, vigorous
addition of aqueous solution of PVA
W/O/W multiple emulsion
Addition of large aqu. phase
Microspheres in solution
Separation, washing, drying MICROSPHERES.
15. SPRAY DRYING AND SPRAY CONGEALING:
Polymer dissolved in organic phase (acetone)
Drug is dispersed in polymer solution under high speed homogenization
Atomized in a stream of hot air
Formation of small droplets
17. SOLVENT EXTRACTION METHOD:
Organic phase is removed by extraction with water
Polymer in organic solvent
Drug is dispersed in organic solvent (water miscible organic solvents like
18. SOLVENT EVAPORATION METHOD:
Suitable amounts of polymer(Eudragit) + chloroform solution of the drug.
The aqueous phase (0.2% PVA (Polyvinyl alcohol) in water).
The mixture was stirred with a propeller at 500 rpm for 3 hrs at 250C.
For complete removal of chloroform.
Filtration & collection.
Washed with deionized water.
Microspheres dried at room temperature for 24 hrs.
19. IONIC GELATION METHOD:
Sodium alginate is dissolved in distilled water.
stirred + drug & calcium carbonate (1:1).
Gelation medium (calcium chloride in 2% glacial acetic acid)(21G syringe needle) .
The gel microspheres formed in solution.
Stirred for 30 min at room temperature.
Then microsphere is collected, washed, dried & stored in desicator.
20. Evaluation of Microspheres:
• Drug content.
• Drug entrapment efficiency.
• Particle size analysis.
• Surface morphology.
• Angle of repose, Bulk density and Tapped density.
• In vitro release.
• Kinetic modeling.
• Stability studies as per ICH guidelines.
21. EVALUATION OF MICROSPHERES:
1) Drug content: UV Spectrometer.
2) Drug entrapment efficiency:
% Entrapment = Actual content / Theoretical content x 100.
3) Particle size : Compound microscope, (Stage micrometer and
Eye piece micrometer).
22. 4) Surface morphology: Scanning Electron Microscope (SEM).
5) Angle of repose: Funnel method (Cone method).
tan θ =h/r
Where h & r are the height and radius of the powder cone.
24. 8) In vitro methods:
United States of Pharmacopeia (USP) dissolution apparatus II.
Rotating paddle apparatus.
9) Kinetic modeling: a) Zero order kinetics: Qt = Qo + Ko t
Qt = Amount of drug dissolved in time t,
Qo = Initial amount of drug in the solution and
Ko = Zero order release constant
25. b) First order kinetics: log Qt = log Qo + K1t / 2.303
Qt = Amount of drug released in time t,
Qo = Initial amount of drug in the solution and
K1 = First order release constant
c) Higuchi model: Qt = KH.t ½
Qt = Amount of drug released in time t and,
KH = Higuchi dissolution constant.
26. d) Korsmeyer - peppas release model: Mt/M∞ = K.tn
Mt / M∞ = Fraction of drug release,
K= Release constant,
t = Drug release time and
n = Diffusional exponent for the drug release that is
dependent on the shape of the matrix dosage form.
27. 10) Stability Studies:
• A stability study as per (ICH) guidelines.
• Accelerated Stability testing studies 6 months.
• Temperature 40 ± 2 ℃ and 75 ± 5 % RH.
• At the end of 1,3&6 months % entrapment & Drug release (Physical
Ophthalmic Drug Delivery
Oral drug delivery
Nasal drug delivery
Buccal drug delivery
Gastrointestinal drug delivery
Transdermal drug delivery
Colonic drug delivery
29. OTHER APPLICATIONS:
• Diagnosis for ex; thermographic detection of tumours.
• Biotechnology industry.
• Culturing of a feline breast tumor line.
• Controlled and sustained delivery.
• Drug targeting.
• Taste masking.
• Aqueous solubility & absorption.
• Improved Stability.
• This area of novel drug delivery has innumerable applications and there is a
need for more research to be done in this area.
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