L15 - Tablet Formation - Introduction

Question 1

Why is particle size so important

Answer 1

can affec:

• drug bioavailability
• settling rate (suspensions)
• possibility of obtaining homogenous mixture (and maintaining it)
• flowabiliy
• other properties iportant for the transformation of powders into tablets
• tolerability of some dosage forms

Question 2

What are the different distributions for particle size

Answer 2

Question 3

What are the true volumes and apparent volumes of powders

Answer 3

• V_{bulk or apparent}
  
  • the volume occupied by a powder including the pores (empty gaps between particles)
• V_true
  
  • the volume occupied by a powder excluding the volume occupied by the pores

Question 4

What is the apparent volume before settling and the apparent volume after settling

Answer 4

• apparent volume before settling (bulk volume)
  
  • the volume of 100g of a susbtance measured in a dry cylinder without compacting
• aparent volume after settling (settled volume)
  
  • (10, 500, 1250) taps and the corresponding volume are read
  • if V₅₀₀ differs from V₁₂₅₀ by more than 2 mL carry out another 1250 taps

Question 5

what is bulk density and true density

Answer 5

Question 6

what is packing fraction

Answer 6

Question 7

What is porosity

Answer 7

• the (percentage) voidage of the powder bed

Question 8

What are the equations for porosity

Answer 8

Question 9

What is the importance of powder flow

Answer 9

important for ensuring uniformity of dosage and weight

Question 10

what are the froces that affect powder flow

Answer 10

• favour
  
  • gravity
  • true density of particles
  • angles of the surface over which particles are flowing
• against
  
  • adhesion forces (particles and container)
  • cohesion forces (particles-particles)

Question 11

What does a high angle of repose show

Answer 11

the powder is cohesive

does not flow

Question 12

what are the angles of repose for a powder that has the flow property: good, passable, poor

Answer 12