Powders

Question 1

what is a powder

Answer 1

pool of solid particles

Question 2

What are the 3 properties of powders

Answer 2

1. Flow like a Liquid
2. compressed like a Gas
3. resists deformation like a solid

Question 3

What are powder particles meant to be like?

Answer 3

• heterogeneously redistributed

- irregular shape

Question 4

Dependent on particle orientation

Answer 4

• martin’s diameter

- Feret’s diameter

Question 5

Independent on particle orientation

Answer 5

• projected area diameter

- projected perimeter diameter

Question 6

what is particle size distribution based on?

Answer 6

• no of particles within each class size

- weight of particles within each class size

Question 7

what happens if all the particles are within the same size class?

Answer 7

-narrow size distribution

Question 8

what does a higher variety of particle size mean?

Answer 8

-wide size distribution

Question 9

how is the narrow/wide size detected?

Answer 9

-curve or frequency histogram

Question 10

what will represent a curve?

Answer 10

-frequency against mean diameter

Question 11

what will represent a frequency histogram?

Answer 11

-frequency against classes size range

Question 12

What are the two types of skewed distribution?

Answer 12

-positively and negatively skewed

Question 13

what does a negative skew mean?

Answer 13

-mode > mean

Question 14

what does a positive skew mean?

Answer 14

-mean > mode

Question 15

what does fraction oversized mean?

Answer 15

-anything bigger than 250 retained into the sieve

Question 16

what does fraction undersized mean?

Answer 16

-anything smaller than 250 goes into the receiver

Question 17

what is powder fineness based on?

Answer 17

-the median

Question 18

what will sieving methods generate?

Answer 18

-weight distribution

Question 19

which forces is flowability dependent on?

Answer 19

• drive flow forces=gravity, particle mass, angle of inclination and applied mechanical force. PROMOTE FLOW.
• resisting flow forces - DRAG FORCES - cohesion and adhesion, surface forces and electrostatic forces.

Question 20

what will a powder flow on?

Answer 20

-flow promoting forces - drag forces

Question 21

will large particles flow better than small particles if all is equal?
will spherical particles flow better than irregular particles if all is equal?
will high true density particles flow better than low true density particles?
will powders with a low moisture content flow better than those with a high moisture content?

Answer 21

• yes
• yes
• yes
• yes

Question 22

what does packing relate to?

Answer 22

• the arrangement of solid particles in a powder bed

- how this will influence volume of powder bed.

Question 23

what is porosity?

Answer 23

-measure of how tightly or loosely particles are packed.

Question 24

what is the bulking density?

Answer 24

-property of a powder bed

Question 25

bulk volume equation?

Answer 25

-true volumes + void volumes

Question 26

What is the true volume?

Answer 26

-volume of single powder particle

Question 27

what is the void volume?

Answer 27

-include inter and intra particular pores.

Question 28

-how is the powder dried (troubleshotting) - POWDER FLOW

Answer 28

• minimum of moisture required

- cohesiveness increased via moisture

Question 29

-how is the shape changed and roughness controlled - powder flow - troubleshotting

Answer 29

-spray dry to produce more regular shaped particles

Question 30

-how is flow promoting forces increased?

Answer 30

• mechanical assistance added

- add excipient - lubricant, anti adherent, glidants

Question 31

-what is the Angle of Repose?

Answer 31

• after powder is left to flow
• cone formed on flat surface
• flatter the cone - smaller AOR - better the flow

Question 32

-how are powders dispensed?

Answer 32

• bulk - multidosecostainer

- single dose - sachet

Question 33

How are oral powders dispensed?

Answer 33

• 5ml spoon

- bottle with a wide opening

Question 34

what are the advantages of oral powders?

Answer 34

• fast absorption
• allows administration of large doses
• shelf life and stability increased

Question 35

what are the disadvantages of oral powders?

Answer 35

• bulky packaging
• organoleptic properties
• drug degradation can happen

Question 36

what are topical powders and what are the advantages and disadvantages?

Answer 36

• external use powders - dusting powders
• packaged in bottles with sifter tops
• absorption of skin moisture
• friction reduced
• easy to use
• possible irritation
• risk of pores blocking
• inhalation risk

Question 37

what are insufflation powders?

Answer 37

• administration in body cavities

- formulated as finely divided powders

Question 38

what is a eutectic mixture?

Answer 38

-two powder ingredients - mixed - start as solid - liquify at room temperature

Question 39

What are the two sources of effervescent powders?

Answer 39

• source of co2 - calcium carbonate / sodium bicarbonate

- source of acid - mixture of tartaric acid and citric acid

Question 40

what happens when effervescent powders are dispersed in h20?

Answer 40

• neutralisation reaction takes place between basic and acidic components
• stored away from moisture - as water interaction will cause neutralisation reaction

Question 41

where are bulk powders stored?

Answer 41

-cool, dry place in a tightly closed container

Question 42

what are hygroscopic powders?

Answer 42

-powders that absorb moisture from the env

Question 43

what are deliquescent powders?

Answer 43

hygroscopic powders that liquify after moisture absorption

Question 44

what are efflorescent powders?

Answer 44

powders that release moisture into the environment