Powder Dose Forms Flashcards
What is a powder?
Intimate mixtures of dry finely divided drugs or excipients that may be intended for internal or external use
What dosage forms can a powder be incorporated?
tablets capsules solutions suspensions topical ointments/cream suppositories
What is micromeritics?
Science of small particles
What characteristics of particles does micromeritics look at?
particle: size distribution shape angle of repose porosity true volume bulk volume apparent density
What can particle size influence?
dissolution rate
suspendability
product uniformity
lack of grittiness
What are 3 advantages to small particle size?
larger surface area so they dissolve faster
remain in suspension longer
provide products with less grittiness
Why is it important for particles to remain in suspension longer?
smaller
important for dose uniformity in oral suspension dose forms
What is the advantage to having particles of similar size and shape?
they blend more uniformly and provide homogenous mixtures
What are 4 methods to determine particle size?
sieving methods
microscopy
sedimentation rate
light scattering
What are 2 methods of determining particle shape?
microscopy
angle of repose
What is angle of repose used for? How is this useful?
estimating the flow properties of a powder
usually is a function of particle size and shape
How do you determine angle of repose?
allow powder to flow through a tunnel and fall freely onto a surface
Measure height and diameter of resulting cone
use tanx = h/r to get tanx, then use arctan of that value to find the angle
What does it mean if a powder has a low angle of repose? High angle of repose?
low: flows freely, indicating a spherical shape and larger particle size
high: poor flow, indicating irregularly shaped particles and small particle size
what angle of repose value indicates a poor flow?
greater than 50°
What influences apparent density of solids?
particle size
What does increasing particle size do to the apparent density? Why?
increases
increasing particle size means there is larger spaces in between the particles leading to a larger apparent volume per unit of mass
What is comminution?
the process of reducing particle size of a solid
What is two ways to reduce particle size?
trituration
levigation
What is a eutectic mixture?
those where the melting point of the mixture is depressed and the mixture liquefies
What are 3 factors which determines whether a eutectic mixture will form?
proportions of which the ingredients are mixed
whether trituration is sued
the presence of other ingredients which may absorb the liquid formed
What are 2 strategies used to overcome eutectic mixtures?
1) allow eutectic to form via trituration and absorb the resulting liquid into a inert diluent
2) Mix the eutectic formers separately with a suitable diluent and combine the protected materials with remaining ingredients via geometric dilution
What are 3 advantages to products in the solid state?
1) more stable in the solid form, shelf life is longer
2) a number of dosage forms can be fabricated and each dose form can contain a different amount of drug and controlled release is possible
3) solid dose forms can be packaged, shipped, and administered easily
What are two classes of powder dose forms?
bulk powders
divided powders
what are bulk powders?
non-potent medications
what are 3 examples of bulk powders?
dietary supplements
antacids
laxatives
What are some characteristics of a good diluent for bulk powders?
inert free of grittiness serves to protect the skin from irritation and friction frequently absorbs secretions exerts a drying effect
What are 5 typical diluents for bulk powders?
bentonite kaolin starch magnesium carbonate talc
Who typically benefits most from divided powders?
children
elderly
what are divided powders?
single doses of powdered medication individually wrapped in paper or foil-plastic laminates
What are granulations?
coarse particles
How are granulations made?
made by blending the powders together then moistening the mixture to form a pasty mass
pass the pasty mass through a sieve and air dry the granules
How are effervescent granules prepared?
mixing granules formulated separately with citric/tartaric acids (1:2) and sodium bicarbonate
this is then added to water and CO2 is liberated
What are some examples of granulation products? Effervescent granulations?
laxatives
effervescent: antacids, ASA containing analgesics
