Micromeritics, Physical Pharmaceutics B.Pharmacy Notes PDF

CONTENTS: Micromeritics: Particle size and distribution, average particle size, number and weight distribution, particle number, methods for determining particle size by (different methods), counting and separation method, particle shape, specific surface, methods for determining surface are, permeability, adsorption, derived properties of powders, porosity, packing arrangement, densities, bulkiness & flow properties

Important Question: On a sight..

• Define Micromeritics. Write applications of Micromeritics in Pharmacy.

• Discuss briefly various methods to determine the particle size of powders.

• Discuss briefly method for determination of particle volume.

• Discuss briefly various methods to determine surface are of powder.

• Define angle of repose. What are the various method to calculate angle of repose? What are the ways to improve flow properties of powder?

• Define densities along with their method of determination.

• Write short notes on Hatch-Choate equation, Carr's Index, Particle Number, Porosity, Specific surface area, etc.

Micromeritics

     It is the science and study of a small particle. It includes fundamental and derived properties of individual & collection of particle. Named by Dalla Valle.

Applications/Importance of Micromeritics:

• Dissolution: Increase in surface area by particles size reduction leads to increase in drug dissolution rate.
• Appearance: Color, Texture and particle size enhancement.
• Flow ability: Granulation technique convert powder into granule of uniform size, to increase flow property.
• Compressibility:  Small Particle size -  enhance compressibility.
• Rheology: More small particles - More particle-particle intration - Increase resistance to flow.
• Weight Uniformity: 
• Drug Release: Small Particle size - enhance drug release.
• Stability: Small Particle size - enhance stability.
• Adsorption: Small Particle size - more surface area - enhance adsorption.
• Mixing: Small Particle size - enhance mixing.
• Drying: Small Particle size - more surface area - enhance mixing.
• Extraction: Small Particle size - enhance extraction.
• Absorption: Small Particle size -  enhance absorption.

Fundamental Properties of Powder:

Particle size & size distribution

• Particle volume.
• Particle number.
• Particle shape.
• Particle surface area.

Particle size range:

0.5μm - 10μm : Suspension & thin emulsion

10μm - 15μm : Flocculating suspension & porous emulsion

15μm - 100μm : Fine Powder

150μm - 1000μm : Coarse Powder

1000μm - 3360μm : Granules.

Important Question: On a sight..

• Why particle size is expressed as equivalent spherical diameter 

Ans:  Because the actual particles of a powder sample are uneven and unsymmetrical in shape.

• Projected Diameter: Diameter of a Sphere have same area as that of asymmetric particle then viewed under optical microscope.
• Stoke diameter: Diameter of a Sphere have same sedimentation rate as that of asymmetric particle.
• Sieve Diameter: Diameter of a Sphere that passes though the same sieve aperture as that of asymmetric particle.
• Volume Diameter: Diameter of a Sphere have same volume as that of asymmetric particle.
• Volume Surface: Diameter: Diameter of a Sphere have same volume to surface areas that of asymmetric particle.