Chapter 6 - Powders and Granules Flashcards
define a pharmaceutical powder (DOSAGE FORM)
a mixture of finely divided drugs or chemicals in dry form.
meant for internal OR external use
true or false
pharmaceutical powders are meant for external use only
FALSE – could be internal or external use
most APIs are in what form?
solid (powder)
how can pharmaceutical powders be classified?
as the dosage form itself OR as substances used like medicinal substances or excipients
name 3 advantages of pharmaceutical powders as a dosage form
-flexibility in compounding
-good chemical stability
-ingredients are rapidly dispersed
true or false
pharmaceutical powders have better stability than liquids
true
name 3 DISADVANTAGES of pharmaceutical powders as a dosage form
time-consuming to prepare
dosing can be inaccurate
unpleasant taste
name 2 medicinal substances that are pharmaceutical powders
crystalline and powder forms
true or false
pharmaceutical excipients can be considered pharmaceutical powders
true
NOT dosage form tho — jjust pharmaceutical powder substance
give an example of a pharmaceutical powder dosage form
solid aerosols
(go back 2 slide 22 and look at textbook for last 2 bullet points)
how is morphology an important particle characteristic of pharmaceutical powders?
a particle with a rough surface will take up water faster than a smooth surface
which uptake water more quickly – powders or granules?
granules
for VEGETABLE AND ANIMAL DRUGS, how many classes of “type of powder” are there ?
name them
5 classes
very coarse
coarse
moderately coarse
fine
very fine
name the sieve size that all particles pass through for each powder class of vegetable and animal drugs
very coarse – all particles pass through #8 sieve
coarse - all particles pass through #20 sieve
moderately coarse - all particles pass through #40 sieve
fine – all particles pass through #60 sieve
very fine - all particles pass through #80 sieve
true or false
the higher the sieve number, the smaller the holes
TRUE
which has larger holes:
a #20 sieve
a #40 sieve
20 sieve has larger holes
for CHEMICAL drugs, how many classes of powder are there based on particle size?
4 classes
coarse
moderately coarse
fine
very fine
true or false
for vegetable/animal drugs, there are 5 classes of powder based on size and for chemical drugs there are 4 classes
TRUE
give the sieve size that ALL PARTICLES PASS THROUGH for each class of chemical drugs
coarse – all pass through #20 sieve
moderately coarse - all pass through #40 sieve
fine – all pass through #80 sieve
very fine - all pass through #120 sive
is a similar particle size range desirable for pharmaceutical powders?
YES
want it to be uniform and homogeneous.
particles of a uniform size are blended easier
particle size range for ophthalmic suspensions and WHY
less than or equal to 10 micrometers
bc the eye is very sensitive we don’t want particle size too large
what is the particle size range for ORAL suspensions
10-50 micrometers
give the particle size range for parenteral suspensions
0.5 - 25 micrometers
give the particle size range for aerosols for the lungs and name an exception
1-5 micrometers
lactose may be around 10 micrometers
for IMMEDIATE RELEASE tablets and capsules, give the particle size range
less than or equal to 50 micrometers
give the particle size range for TOPICAL aerosols
50-100 micrometers
give the particle size range for topical emulsions and for topical suspensions
topical emulsions: less than or equal to 50 micrometers
topical suspensions: 10-50 micrometers
explain desirable/undesirable particle shapes for pharmaceutical powders
spherical particles are desired because they tend to be easier to mix
needle shaped and cubic shaped particles tend to clog or stick together bc they don’t slide over each other as easily as spherical particles
explain why particle density is an important consideration for the pharmaceutical powder dosage form
higher density particles will tend to sink and lighter density particles will rise
2 layers will form
explain why electrostatic charge is an important consideration for the powder dosage form
static electricity will hamper (interfere) with the blending of the particles, therefore no charge is desired
as mentioned, any electrostatic charge will interfere with the blending of the particles in a powder.
how is this issue solved?
-humidification of the work area
-include small quantity of SLS or similar material to neutralize the charges
true or false
the adhering/repelling properties of particles in the powder dosage form is not important
false - it is
why is camphor an important consideration when used in the powder dosage form
it is slightly gummy, and crystalline
it needs to be reduced in its particle size (pulverization by intervention)
explain pulverization by intervention
name a substance it must be used for and why
camphor bc it’s crystalline and slightly gummy in nature. needs to get its particle size reduced
mixed with “intervening solvent” like alcohol or acetone and camphor will DISSOLVE.
the solvent then evaporates and the powder will recrystallize out of the solution as FINE PARTICLES
Name the 5 effects of particle size on pharmaceutical properties.
which is always the #1 concern?
dissolution rate
suspendability
uniform distribution
penetrability
nongrittiness
dissolution rate is always #1. powder must dissolve, or no absorption will take place
TRUE OR FALSE
drug micronization can decrease the rate of drug dissolution and its bioavailability
FALSE
increase the rate of dissolution and increase bioavailability
true or false
the smaller the particle size, the increased rate of dissolution and the increased bioavailability
true
what does suspendability mean?
what is the particle size range for it?
suspendability – desire for the particles to remain UNDISSOLVED but UNIFORMLY DISPERSED in the liquid vehicle
0.5-10 micrometers
explain penetrability and how the particle size range is a consideration
to be inhaled for DEPOSITION deep in the respiratory tract
0.5 micrometers - 10 micrometers
penetration, then deposition
what is nongrittiness?
is it desirable?
how is particle size a consideration?
nongrittiness - lack of grittiness of solid particles in dermal ointments, creams, and ophthalmic preparations
50-100 micrometers is the particle size range
true or false
nongrittiness is not a requirement for ophthalmic preparations
false - it is
why is uniform distribution important?
want all particles to be in similar size range
the drug substance should be uniformly distributed in the dosage form to ensure dose-dose content uniformity
what is micromeritics
the science of small paticles
define true density
the mass/unit volume of the solid material ITSELF, EXCLUSIVE of inter and intra particle pores or void space
(tapped density)
define bulk density
mass of powder/bulk volume of the given mass
INCLUDES the open spaces of air that contain no powder
knowing the bulk density is an important factor in determining what?
the proper size dose form or the proper size of the container for a given powder
formula to calculate angle of repose.
is a low or high value better?
why?
theta = tan^-1 (h/r)
a LOW value is better bc this means it will spread and have better flow
true or false
the volume of a capsule fluctuates
FALSE - it’s constant
as mentioned, a capsule has a constant volume.
thus, if you’re using a high density material to fill it, will you need a lot of the material or a little bit?
a lot
how do you find the volume for tapped density
if the powder is water INSOLUBLE, submerge it in water
DO NOT WANT IT TO DISSOLVE
In “true density”, the volume used is of the solid material itself and not…..
not inter and intra particle pores or void space
name the 2 MAIN methods for measuring particle size
sieving method
microscopic method
what particle size range can the sieving method measure?
50 - 3360 micrometers
what particle size range can the microscopic method measure
0.2 - 100 micrometers
besides the sieving method and microscopy method, name 4 other methods for measuring particle size
sedimentation rate
light energy diffusion
laser holography
cascade impactation
the higher the sieve number, the ________ the sieve opening
smaller
what particle size can sedimentation rate measure?
what is it based on?
0.8 - 300 micrometers
based on Stokes law
what particle size range can light energy diffusion measure?
0.5 - 500 micrometers
what particle size range can laser holography measure
1.4-100 micrometers
in the sieving method, the sieve with the ________ number will be on the top
smallest # — most coarse
bottom will have smallest particles and largest # mesh
what is used to analyze the sieving method
a bell curve is plotted
in the sieving method, a bell curve is plotted to analyze the results.
is it desirable to have a wide or narrow bell curve? why?
want a narrow bell curve
if it’s too wide, this means that some particles will be very large and some will be very small – not uniform and will not blend easily
which will have a higher mean opening:
sieve no. 80/100
sieve no. 20/40
20/40 will have a higher mean opening
what does it mean:
“sieve # 20/40 “
the particles passed the 20 sieve but not the 40 sieve
what is the symbol for weight retained in the sieving method
G
if a sieve has the highest G value out of all the others, what does this mean
the majority of the particles are the average between the sieve numbers
ie: if highest weight retained was 20/40, most of the particles in that weight retained value are the average of 850 micrometers and 425 micrometers – which is 630 micrometers
how to find mathematically the average particle size using the sieving method
d av = sum of (%retained) * (avg size) / 100
explain the microscopic method of measuring particle size
direct counting of not less than 200 particles in a single plane, using a calibrated ocular
what is the downside of the microscopic method?
how can this downside be taken away?
downside is that the # of particles is not enough to represent the entire powder
to fix this, just count 200 particles multiple times
define comminution
is it small scale or large scale?
cutting, chopping, crushing, grinding, milling, micronizing, and trituration
can be small scale or large scale
give 3 equipments used in large scale comminution of drugs
coarse crusher
intermediate grinders
fine grinding mills
explain the coarse crusher equipment for the large scale comminution of drugs in more detail
roll and impact crusher
explain in more detail the intermediate grinders used in the large scale comminution of drugs
attrition, rolling, and impact mills
explain in more detail the fine grinding mills used in the large scale comminution of drugs
ball, hammer, colloid mills, fluid energy mill, high-speed mechanical screen, and centrifugal classifier
true or false
fluid energy mills are an example of intermediate grinders used in the large scale comminution of drugs
false - ex of fine grinding mill
name 4 methods for the comminution of drugs in SMALL SCALE
trituration
levigation
pulverization by intervention
trituration and sieving
for the small scale comminution of drugs ,what is the first choice?
trituration ONLY
what is trituration
grinding the drug in a mortar to reduce its particle size
what are the different mortars?
when would 1 be used over the other?
glass mortar and wedgewood mortar
use wedgewood when it is desired to reduce the particle size (bc of rough surface)
in trituration, should a glass or wedgewood mortar be used? why?
a wedgewood mortar should be used bc the def of trituration is “grinding drug in mortar to reduce its particle size”
name 2 examples of when levigation should be used
if the liquid is not easily removed a the end of the process
if the liquid is allowed to remain as part of the preparation (usually the case)
explain what levigation is
it is trituration (grinding drug in mortar to reduce particle size) but with a NONSOLVENT
Levigation improves _______.
how?
improves wetting by the use of a liquid with a LOW SURFACE TENSION and LOW VISCOSITTY
give 2 examples of levigating agents and when they should be used
mineral oil and glycerin
mineral oil should be used for hydrophilic drugs and glycerin should be used for hydrophobic drugs (NONSOLVENT)
TRUE OR FALSE
levigating agents do not remain in the product
false - they do
should the levigating agent be volatile or non volatile?
non volatile
what kind of mortar should be used for levigation
wedgewood
if trituration and levigation aren’t suited, what is the next option for the small scale comminution of drugs?
pulverization by intervention
rank the following by the order in which they should be done first for small scale drug comminution (if possible)
levigation
pulverization by intervention
trituration
trituration and sieving
should be done first:
trituration
levigation
pulverization by intervention
triturating and sieving (last)
