EXAM 3 L2 Flashcards
Major types of powder dosage forms
Orally administered
Topical powder
Inhalation powder
Physiochemical properties of powders
Particle size
Particle shape
Particle density
Solid state properties
T/F: Particle size or size distribution can affect “processability” of the powders, and formulation performance
True
Noyes Whitney Equation
Dissolution of powders
Suspendability of suspensions
Uniformity of mix in liquids/powders
Particles aerosol behavior for inhalation
Segregation if powders have wide size distributions
Sieving
Different sieves have different aperture (mass based size)
Particle size distribution
D10, D50, D90, - shows how wide distribution is
Laser diffraction
Measure particle sized distribution; volume based size
Particle density two components
true density and bulk density
Powder flowability
How easy the powder moves from one place to another
Important for material conveying and transportation, as well as capsule and tablet die filling
Effects of powder properties on flowability
-Smaller particles usually have worse flowability
-Spherical particles generally have better flowability then need and plate shaped part.
-Milled part. are cohesive (sticky) and have poor flow
Measurements of powder flowability
-Angle of response: funnel; angle of pile
-Carr Index: tapped density
Powder comminution - particle size reduction strats.
-Improve dissolution and absorption
-Improve mixing homogeneity
-Effects of size reduction depend on design of the equipment, energy and shear inputs and properties of the materials
Powder Comminution Methods:
-Mechanical milling
-Ball Mill: rotate and break particles with grinding medium
-Hammer Mill: Rotate at very high speed (with blades inside)
-Jet Mill: break down particles to VERY small size (1 micron)
Powder Mixing (blending)
Mixing is a unit operation involving the manipulation of a heterogeneous physical system with the goal of making it homogeneous
Major types of blending:
-Tumble blender( V-blender, Tote Blender, Turbula Blender): Passes it side to side to mix
-Blade blender: high shear blender, very big blades under blending chamber
Granules
-Dry aggregates of particles
-Can be used as a dosage form
-Mostly are used for making capsules and tablets
-To improve powder flowability, reduce dusts, and enhance compact-ability
Wet Granulation Process:
-Blending
-Adding Binder
-Granulation
-Drying
-Sieving
Ex. - High shear granulation
Dry Granulation Process:
-Blending
-Compression
-Size Reduction
Ex. Roller Compaction
Dry Granulation properties
-No liquid, which is suitable for some drugs that are unstable in liquid form
-Less processing steps and fewer risks compared to wet granulation
-Lose some compact-ability for tableting
