Week 10

Question 1

Importance of Micromeritics

Answer 1

Particle size and shape can affect the physical, chemical, and pharmacological properties of a drug.

Impact on drug performance, manufacture, formulation stability

Question 2

How can particle size influence formulation stability?

Answer 2

Dissolution: The smaller the faster the dissolution
Dispersion: The smaller in emulsion -> less creaming
The smaller in suspension -> less caking
Inhalation: small size needed to flow to lungs
Aesthetics in semisolids: to make ointment feel smooth

Question 3

What are mono and polydispersed particles?

Answer 3

Monodispersed: the contribution of particle size is narrow (the average value is more meaningful)

Polydispersed: large contribution of particle size - dense packing, caking

Question 4

What particle shape in powder is preferred?

Answer 4

Round (spherical), because it flows better and makes better calculations and predictions of flow

Question 5

How is particle size determined?

Answer 5

Microscope(micrometer-scale)
Sieving
Sedimentation
Light scattering: variation in light scattered as a laser beam passes through dispersed particles

Question 6

How are particles measured with sieves?

Answer 6

USP provides sieves from very fine - very coarse
Standardized sieves containing few sieves with large sieve mash size and many sieves and small mashes

Question 7

What is the true volume?

Answer 7

True density: g/ml mass in volume

Question 8

What is the Bulk density?

Answer 8

True volume + void space; 1g/2ml Bulk density is smaller than true density

bulk density: 0,5g/ml –> Bulkiness (flipped units): 1ml/g

Question 9

What is Void?

Answer 9

Void = void volume as a fraction of total volume

Void = V(bulk) - V(total) / V (bulk)

Question 10

Porosity

Answer 10

Void percent (*100)

Question 11

Flow of powder

Answer 11

Angle of repose = high angle -> much cohesion -> worse flow due to formation of the peak

Question 12

How is the angle of repose measured?

Answer 12

The powder is released on a round surface (diameter known) until a heap is formed -> measurement of height -> calculate angle with diameter and height

Question 13

What is the effect of moisture on the angle of repose?

Answer 13

it will increase because water will interact with it and cause resistance,
it will not flow so nice downwards anymore due to interaction with water

Question 14

How to increase the flow of powders?

Answer 14

add Glidants (lubricants) like Magnesium, talc, corn, starch, zinc stearate it will coat the part of friction between the wall of the container and the material is minimized -> improving flow

Question 15

What is comminution?

Answer 15

reducing the particle size of powder or aggregates of powder material

Question 16

Trituration

Answer 16

Rubbing or grinding of powder material in a mortar
porcelain is better than glass

For compounding solids

Question 17

Pulverization

Answer 17

Add solvent (camphor, alcohol, ether) to dissolve -> spread via evaporation, leaving fine particles

NOT for compounding

Question 18

Levigation

Answer 18

disperse solid in viscous liquid -> grinding with liquid
used for compounding semisolid in small scale