Module 7 Flashcards
are composed of solid particles with spaces between the particles that contain a gas (most often
air).
Powders
A material is generally considered a powder when
particle size is less than _____.
40 microns
A _________ is a small compact particle of a substance.
granule
A material is generally considered a granule when
particle size is greater than _____.
40 micron
A physical state of a single chemical substance or single drug.
POWDERS IN PHARMACEUTICALS
A _______ is a mixture of finely
divided drugs or chemicals in dry form meant for internal or external use.
pharmaceutical powder
Raw materials (_________) are typically
processed as powders.
API and excipients
The presence of molecular
forces produces a tendency
for solid particles to stick
to themselves (__________)
and to other surfaces
(________).
cohesion; adhesion
Other interparticle
interactions may be due to:
i. __________
between adsorbed liquid
layers at the particle surfaces
ii. ____________ arising
from contact or frictional
charging
Surface tensional forces; Electrostatic forces
Powder and granular systems must be considered as a _______ whose behavior is a function of both the fundamental properties and the external factors.
multiphase continuum
The ___________ of the powder and
individual particles (for example size, shape, surface
texture and moisture content)
fundamental properties
Such as humidity temperature and
consolidation history.
external factors
Powder behavior is generally related to _________.
interparticle interactions
Physical property: Powders are ______ particles while granules are small _________.
fine; grains
Physical property: Powders are acted upon by _________ forces while granules are acted upon by ____________ forces.
adhesion and frictional; gravitational
Powders has _______ flow while granules flow _________.
poor; well
Powders have ______ compressibility while granules have _________ compressibility.
poor; better
Rheological properties of powders and granules include:
Flow and compressibility
Powders are _____ stable due to ______ surface area.
less; higher
Granules are _________ stable due to having ______ surface area.
more; less
Powders are _______ to caking while granules are ________ to harden and cake.
prone; less likely
Powders have ______ wettability while granules are _________ wetted.
low; easily
Powders are ______ to dust formation while granules have ______ dust formation.
prone; less
Powders have a high chance of ___________ dosing while granules have better _________.
non-uniform; unifomity
Powders need a _________ method of processing while granules involves ________ processing, exposure to ________ and ___________.
simpler; more; heat; solvents
________ are objectively better as a material, yet _________ are used more often from R&D to manufacturing of drugs.
Granules; powders
Granules perform better than powder in
flow, compressibility, stability, caking tendencies, wettability, dust formation, and uniformity
Powder performs better than granules in
Physical property and processing
Understanding of the properties and behavior of powders and
granular media is essential for
industrial applications because of
pneumatic transport and tableting processes.
Variance in particle properties
can create handling challenges
that impact the ability of the
powder to move around the
manufacturing process using
hoppers and silos
Correctly _________ a
powder can provide a good understanding of powder
behavior which can help improve processing techniques.
characterizing
_______ are tested for properties such as composition,
particle size, morphology, etc. while _________ is
evaluated via material density, flowability, electrostatic
properties, blend stability, and so on.
Individual particles; Bulk powder behavior
__________ has traditionally been considered
to affect powder behavior, but there are other particle
properties that influence the overall behavior o f the powder.
PARTICLE SIZE & SHAPE
POWDER BEHAVIOR IN BULK
1 . Mixing
2 . Flowability
3 . Compressibility
4 . Dissolution
________ in its simplest definition means “ to put together in one mass .”
MIXING
________ means to mix smoothly and inseparably together
during which a minimum energy is imparted to the bed.
BLENDING
Physical property in mixing that shows if components are of different densities, the denser one will sink through the lighter one.
MATERIAL DENSITY
Physical property in mixing that shows the difference in particle sizes of components is the
main cause of segregation in blends and mixes.
PARTICLE SIZE
Physical property in mixing that shows the more the particle deviates from a spherical
shape, the greater the difficulty of mixing.
PARTICLE SHAPE
Why do we mix? To achieve ________.
homogeneity
Define for the application
considered what means “homogeneous” and
“inhomogeneous”.
HOMOGENEITY
Standards on determining homogeneity of a mixture are set by the industry, the customers, or an external regulation.
INDUSTRY SPECIFIC
INDUSTRY SPECIFIC standards for food industry sampling size.
serving
INDUSTRY SPECIFIC standards for pharmaceutical sampling size.
dose
Occurs when there are high concentration of orange particles in one area and others of high concentration of blue particles.
Segregation
If there is a high coefficient of variation, then the mixture is ____ homogeneous.
less
_________ occurs when the motion of individual
particles is biased according to their characteristics.
SEGREGATION
In the absence of such bias in particle characteristics,
individual motion invariably leads to __________.
homogenization
Segregation limits the ______ in a mixer. All mixtures will undergo ________.
extent of homogeneity; de - mixing
__________ can be classified
depending on the physical
characteristics and flow conditions subjected to the mixture.
SEGREGATION OF GRANULAR
MATERIALS
Three types of segregation of granular materials.
trajectory, percolation, fluidization
Factor that is main cause of segregation.
Particle size
Tendency to segregate is higher the larger the disparity in component _______.
particle size
For non-aerated samples, gentle vibration of a sample may encourage smaller particles to move ______, and larger particles to ________ to the surface.
downward; rise
If we have a very narrow particle size distribution, segregation is due to ____ and _____.
Material density; particle shape
If the denser particles form the lower layer: the degree of mixing _________ gradually until an equilibrium is attained (not necessarily complete mixing).
increases
If the denser particles form the lower layer : the degree of mixing increases to a maximum, then _______ as the _____ component falls through the _______ one.
drops to equilibrium; denser; lighter
T/F: The order of addition of components to the mixer is crucial!
True
According to shape, ___________ particles are easily mixed but also easily segregates.
Spherical
According to shape, particles of ________ shape are difficult to segregate if mixing has been achieved.
irregular
For particle shape, spheres interact by _______; cubes by _____________; and 3D cross by ________.
tangent, face to face, interlock
_______ is a property that defines an ability of a powdered material to flow.
Flowability (powder flow)
Flowability is the ratio of the __________ holding the
particles together vs the _______ trying to pull them apart.
cohesive forces; gravity forces
_____ is a measure of the amount of strength the material retains at a stress-free surface following consolidation to a stress level.
Flow function (ff)
Flow function (ff) describes _________ as a function of _______.
cohesive strength; compaction pressure
Factor of flowability that states that the presence of molecular forces produces a
tendency for solid particles to stick to themselves and to other surfaces.
COHESION & ADHESION
_________ particles have better flow. ________ surfaces have tendencies to interlock, thus have poorer flow.
Spherical; Rough
Fine particles with very high surface to mass ratios are more ______ than coarser particles which are influenced more by _______
forces. More cohesion means _______ flow.
cohesive; gravitational; less
Other factors that may affect cohesive forces between particles (e.g., moisture, electrostatic charges, impurities).
ALTERATION OF SURFACE FORCES
Classification of flowability testing methods
Flow rate
Density ratio
Angle of repose
Shear cell
Others
The reduction in the volume of a powder bed due to the application of stress.
Compression
The transformation of powder into an intact compact with measurable strength and defined shape by the application of a compression pressure.
Compaction
__________ is the
process of the gaseous
phase displacement
from granules or
powders.
Compression
__________ is the
process of consolidation
of particles, with
compression being a part
of this process.
Compaction
Compressibility is a measure of the _______ change a sample undergoes when
pressure is applied.
relative volume
Compressibility describes the relationship of _______ to ______.
bulk density; applied pressure
Bulk density is the ratio of
Split mass to volume after compression (g/ml)
Compressibility index is the ratio of
Density after compression to conditioned bulk density
Particle size exerts a greater
influence on _________ of
powders compared to particle
shape.
compressibility
Compressibility is an identifier
of _________.
powder flow behavior
_________ is the fraction of the
space filled by the figures making up the packing.
Packing density
Packing density is equal to
Bulk density * weight fraction / specific gravity
Moisture increases the _______ of the powder bed and decreases ______, promoting ________.
tensile strength; density variation; inter-particulate bond formation
In general, the presence of moisture enables powder
compaction to operate at a lower _______ requirement.
pressure
Compressibility behavior improves the higher the ________ but a shift occurs in the trend once ___________ is achieved.
moisture content; optimum moisture
Compaction leads to an increase in average surface
________.
temperature
With a faster compaction, the __________ the temperature increase.
higher
Compaction leads to an increase in temperature primarily due to the increasing degree of ________ (volume reduction) and the effect of _________ (wall friction) .
powder deformation; interparticle interaction
In pharmaceuticals, temperature rise in the compressed powder can affect
physiochemical properties of the powder, such as ______ degradation and
change in _________.
thermal; crystallinity
Compression may lead to
_________.
polymorphism
T/F: Each polymorph form has its own set of physical properties – one form may have poor compressibility, while another form has superb compressibility .
True
The process in which a substance forms a solution.
DISSOLUTION
The dissolution of a drug is important in determining
its ________ and ________.
bioavailability; therapeutic effectiveness
________ correlates the dissolution rate of a drug with particle characteristics and properties.
Noyes –Whitney equation
The ________ of the powder in the dissolution medium
highly influences the dissolution performance of the drug.
solubility
Solubility changes depending on ___________ characteristic.
solid - state
Considering particle size, the dissolution rate of a material depends on its _________.
specific surface area
General rule: with ______ particle sizes, there is ______specific surface area and thus________________ dissolution.
smaller; larger; faster
__________ are legally binding
collection of standards and quality specifications for drugs.
Pharmacopoeias
Pharmacopoeias include
Standard tests for identification, purity, strength, dosage, and other performance characteristics
Formulation and drug preparation
Analytical methods, dissolution
testing, stability, microbial purity
The ________ is the
constant, three -dimensional angle (relative to the horizontal base) assumed by a cone -like pile of material formed by any of several methods.
angle of repose
Step 1 in getting the angle of repose: Form the angle of repose on a fixed base with a
_________ to retain a layer of powder on the base. The base should be free of _______.
retaining lip; vibration
Step 2 in getting the angle of repose: Vary the height of the __________ to carefully build up
a symmetrical cone of powder. Care should be
taken to prevent ________ as the funnel is moved.
funnel; vibration
The funnel height should be maintained approximately __________ from the top of the powder
pile as it is being formed to minimize the impact
of _____ on the top of the cone.
2-4 cm; falling powder
Determine the angle of repose by measuring the
height of the cone of powder and calculating the
angle of repose, using the following equation:
tan(alpha) = height/0.5/base
The _________ has been proposed as an indirect measure of bulk density, size and shape, surface
area, moisture content, and cohesiveness of materials because all of these can influence the observed
compressibility.
compressibility index
The ______ and the _______are
determined by measuring both the bulk volume and the
tapped volume of a powder.
compressibility index; Hausner ratio
Compressibility index is computed by
100 x (V_o-V_f)/V_o
Hausner ratio is computed by
Vo/Vf
The CI and HR are not _______ properties of the powder and
as such depend a lot on the methodology.
intrinsic
Considerations of the following are important on the CR and HI:
- Diameter of the cylinder used
- Number of time the cylinder is tapped
- Mass of material used in the test
- Rotation of sample during tapping.
_____ is used for powder surface investigation with a probe scanned over a surface.
ATOMIC FORCE MICROSCOPY (AFM)
Analytical techniques for powder characterization
ATOMIC FORCE MICROSCOPY (AFM)
PARTICLE SIZE ANALYZERS
Surface Electron Microscopy
