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PHRD5925 Pharmaceutics Lecture 16 - Pharmaceutical Powders
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do most pharmaceutical powders show a normal size distribution?
NO
PDI
polydispersity index (squared std dev./mean diameter)
PDI < 0.1
monodisperse particles
5 pharmaceutical bulk properties affected by particle size
1) bulk density
2) porosity
3) surface area
4) flowability
5) dissolution/wettability/solubility
density without consideration of voids (no inter/intra-particle pores)
true density
density that includes inter/intra-particle spaces of the particle when considering the volume
bulk (apparent) density
measure of void volume in a powder material
porosity
defines how cohesive/adhesive something is
contact angle (
)
larger contact angle = _____ wettability
lower
help solvent penetrate the pores of the powder
wetting agents
smaller particle size = ____ angle of repose (
)
larger (decreased flow)
process of reducing particle size or aggregates of powders
milling (comminution)
3 methods of milling/comminution
1) trituration
2) pulverization by intervention
3) levigation
continuous rubbing/grinding w/ a mortar & pestle; useful for hard powders
trituration
useful for hard, crystalline powders that do not easily triturate or gummy substances
pulverization by intervention
uses a small amount of solvent in which the particles are insoluble, then triturate w/ mortar & pestle; useful when making ointments & suspensions
levigation
blending needs to be redone if RSD > _____
6%
Author
daynuhmay
ID
271311
Card Set
PHRD5925 Pharmaceutics Lecture 16 - Pharmaceutical Powders
Description
Pharmaceutical Powders
Updated
2014-04-21T08:06:54Z
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