form 3

Question 1

why Granulation of powders is important

Answer 1

increase size of particles –> increases flow –> increase uniformity

Question 2

why uniform flowability is important

Answer 2

• ensures reproducibility of dose

- reproducible fill weight

Question 3

how cohesion impact uniform flowability

Answer 3

• same particles stick together
• all active ingredient particles may stick together cause agglomeration prevents even distribution
• worse for smaller particles as greater SA to interact

Question 4

how Adhesion impact uniform flow

Answer 4

• adhesion = particles stick to surface e.g. di surface

this prevents even distribution of ingredients

Question 5

measuring cohesion/ adhesion

Answer 5

-Angle pose
glass slab, funnel = pour powder through funnel to the glass slab measure the angle of slope. The more cohesive the greater the angle of slope as less flowability particles just pile together instead of evenly distributing.

-Shear strength
apply stress on powder bed compare stress required to move top plane compared to bottom. Measuring this give a flow factor the greater the flow factor = less cohesive = better flow (e.g. above 10)

-Tensile strength
measure stress required to break powder bed the more cohesive the greater the stress required.

Question 6

Factors that impact cohesiveness

Answer 6

• particle density - the greater the density the less cohesive works with gravity to flow
• particle shape - spherical shape has minimum contact so less cohesively
• packing geometry= measure by pouring powder into a cylinder measure initial vol then 50 taps record vol repeat until vol is constant. More cohesive the less easily particles are rearranged so packing/ compression is harder and required more force. Less compression more air trapped so prone to oxidation
• particle consolidation ( ability for particles to form stable interaction to sustain compression) = the more cohesive the particles the more they can do this but initial compression is hard with very cohesive particles due to poor particle rearrangement

Question 7

what is the hausner ratio and what does it measure

Answer 7

tapped density/ bulk density

measures cohesion = more cohesive will have greater hausner ratio greater than 1.6 so reduced flow

Question 8

what is the Carr’s index and what does it measure

Answer 8

tapped density- bulk density/ tapped density x 100

measures flowability the smaller the number the greater the flow (5-12) = excellent flow

Question 9

determine powder flow rate method

Answer 9

measure rate at which powder flows from the hopper

Question 10

improving flowability of powders

Answer 10

• shape + size -make particles more coarse(bigger) by granulation and spherical (flow better than irregular) use spray drying for this
• texture- smoother particles flow better as less friction
• Moisture- 8-10% is optimum to act as lubricant over surface improve flow any greater will cause particles to stick and reduce flow.
• add additives like silica, mg sterate these coat particle minimise (particle-particle interaction/ cohesiveness).
• using vibration hopper- this promotes powder flow

Question 11

uses of powders

Answer 11

• inhalation ( must be 1-5 microns this means increase cohesiveness so poor flow to overcome this the powder is coated on carrier molecules like lactose which improve flow help fill drug into canister, during areosalation lactose detach from drug allows drug move to lungs
• oral powders = bulk powders for drugs non toxic taken in large doses or divided doses (lempsip).
• powders for reconstitution e.g. antibiotics and injection

Question 12

advantages of powders oral powders

Answer 12

• faster dissolution than tablets
• more stable than liquids
• suitable when you need large doses of drug

Question 13

disadvantages of oral powders

Answer 13

• not suitable for drugs with poor taste

- not suitable for potent drugs