Powder Dose Forms

Question 1

What is a powder?

Answer 1

Intimate mixtures of dry finely divided drugs or excipients that may be intended for internal or external use

Question 2

What dosage forms can a powder be incorporated?

Answer 2

tablets
capsules
solutions
suspensions
topical ointments/cream
suppositories

Question 3

What is micromeritics?

Answer 3

Science of small particles

Question 4

What characteristics of particles does micromeritics look at?

Answer 4

particle:
size
distribution
shape
angle of repose
porosity
true volume
bulk volume
apparent density

Question 5

What can particle size influence?

Answer 5

dissolution rate
suspendability
product uniformity
lack of grittiness

Question 6

What are 3 advantages to small particle size?

Answer 6

larger surface area so they dissolve faster
remain in suspension longer
provide products with less grittiness

Question 7

Why is it important for particles to remain in suspension longer?

Answer 7

smaller

important for dose uniformity in oral suspension dose forms

Question 8

What is the advantage to having particles of similar size and shape?

Answer 8

they blend more uniformly and provide homogenous mixtures

Question 9

What are 4 methods to determine particle size?

Answer 9

sieving methods
microscopy
sedimentation rate
light scattering

Question 10

What are 2 methods of determining particle shape?

Answer 10

microscopy

angle of repose

Question 11

What is angle of repose used for? How is this useful?

Answer 11

estimating the flow properties of a powder

usually is a function of particle size and shape

Question 12

How do you determine angle of repose?

Answer 12

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

Question 13

What does it mean if a powder has a low angle of repose? High angle of repose?

Answer 13

low: flows freely, indicating a spherical shape and larger particle size
high: poor flow, indicating irregularly shaped particles and small particle size

Question 14

what angle of repose value indicates a poor flow?

Answer 14

greater than 50°

Question 15

What influences apparent density of solids?

Answer 15

particle size

Question 16

What does increasing particle size do to the apparent density? Why?

Answer 16

increases
increasing particle size means there is larger spaces in between the particles leading to a larger apparent volume per unit of mass

Question 17

What is comminution?

Answer 17

the process of reducing particle size of a solid

Question 18

What is two ways to reduce particle size?

Answer 18

trituration

levigation

Question 19

What is a eutectic mixture?

Answer 19

those where the melting point of the mixture is depressed and the mixture liquefies

Question 20

What are 3 factors which determines whether a eutectic mixture will form?

Answer 20

proportions of which the ingredients are mixed
whether trituration is sued
the presence of other ingredients which may absorb the liquid formed

Question 21

What are 2 strategies used to overcome eutectic mixtures?

Answer 21

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

Question 22

What are 3 advantages to products in the solid state?

Answer 22

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

Question 23

What are two classes of powder dose forms?

Answer 23

bulk powders

divided powders

Question 24

what are bulk powders?

Answer 24

non-potent medications

Question 25

what are 3 examples of bulk powders?

Answer 25

dietary supplements
antacids
laxatives

Question 26

What are some characteristics of a good diluent for bulk powders?

Answer 26

inert
free of grittiness
serves to protect the skin from irritation and friction
frequently absorbs secretions
exerts a drying effect

Question 27

What are 5 typical diluents for bulk powders?

Answer 27

bentonite
kaolin
starch
magnesium carbonate
talc

Question 28

Who typically benefits most from divided powders?

Answer 28

children

elderly

Question 29

what are divided powders?

Answer 29

single doses of powdered medication individually wrapped in paper or foil-plastic laminates

Question 30

What are granulations?

Answer 30

coarse particles

Question 31

How are granulations made?

Answer 31

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

Question 32

How are effervescent granules prepared?

Answer 32

mixing granules formulated separately with citric/tartaric acids (1:2) and sodium bicarbonate
this is then added to water and CO2 is liberated

Question 33

What are some examples of granulation products? Effervescent granulations?

Answer 33

laxatives

effervescent: antacids, ASA containing analgesics