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Micromeritics – Essay Questions
Define micromeritics and discuss its pharmaceutical significance.
Guide points: Explain the concept of micromeritics, list its main parameters, and relate how
particle characteristics affect drug dissolution, suspendability, inhalation, and topical
formulations.
Describe and compare the fundamental and derived properties of particles.
Guide points: Define each property; classify them into fundamental (size, shape, distribution)
and derived (density, porosity, flow). Explain how one influences the other.
Discuss different methods used to measure particle size, stating the principle and
application of each.
Guide points: Cover air permeation, adsorption, Coulter counter, optical microscopy, sieving,
and sedimentation (Andreasen pipette). Mention size ranges and advantages/limitations.
Explain the concept of equivalent diameter and why multiple definitions of particle
diameter are necessary.
Guide points: Describe how irregular particles are expressed in terms of equivalent spherical
diameters (surface, volume, projected, sieve, Stokes). Provide examples of situations where
each is used.
Elaborate on the effect of particle size distribution on pharmaceutical formulation
and performance.
Guide points: Define frequency and cumulative distribution curves, explain the concept of
mode, and discuss how narrow vs. broad distributions affect uniformity, flow, and
dissolution.
Describe in detail the different types of density measurements and their
pharmaceutical applications.
Guide points: Differentiate true, granule, and bulk density; outline measurement methods
(helium, mercury, water displacement). Relate density to porosity, compaction, and
packaging.
Define porosity and discuss how packing arrangement affects powder behavior.
Guide points: Give the formula for porosity; discuss theoretical minimum/maximum values,
effect of particle size variation, and how flocculation or aggregation influences void volume.
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