Pharmaceutics: Excipients for IR Tablets

Question 1

What is an IR tablet?

Answer 1

An immediate release tablet is one in which the majority of the drug is released in a short amount of time.
~70-75% of the drug is released in 45minutes.

Question 2

What excipients are required in the formation of the IR tablet?

Answer 2

1. filler (diluent)
2. binder
3. lubricant
4. anti-adherent
5. glidant

Question 3

what excipients are needed for the organoleptic enhancement of IR tablets?

Answer 3

1. coating
2. colourant
3. flavouring

Question 4

what excipients are required for the dissolution and adsorption of the IR tablets?

Answer 4

1. disintegrant
2. matrix former
3. dissolution enhancer
4. absorption enhancer

Question 5

What is the role of a filler/diluent?

Answer 5

to bulk up the tablet to a minimum size necessary for handling.

Question 6

What is the role of a binder?

Answer 6

an adhesive that increases compactibility and mechanical strength of a tablet.

Question 7

What is the role of a lubricant?

Answer 7

to reduce friction between the tablet and the die during ejection. reduces particle-equipment and particle-particle interactions hence lowering friction.

Question 8

What is the role of an anti-adherent?

Answer 8

to prevent powder/tablet adhesion to punches.

Question 9

What is the role of a glidant?

Answer 9

to improve powder flow which improves mixing and content uniformity

Question 10

What is the role of a disintegrant?

Answer 10

to break up tablets into smaller particles which increase SA hence dissolution rate.

Question 11

What is the role of a coating?

Answer 11

to mask unwanted taste, improve the ease of swallowing, reduce friability and improve stability.

Question 12

What is the role of a colourant?

Answer 12

to aid tablet identification

Question 13

What is the role of flavourings?

Answer 13

to enhance tablet taste but isn’t commonly used in tablets for swallowing.

Question 14

common excipients that can be found in all IR tablets?

Answer 14

1. lactose
2. natural starch
3. pregelatinised starch
4. cellulose
5. microcrystalline cellulose
6. talc
7. magnesium stearate
8. colloidal silicon dioxide

Question 15

what does povidone do?

Answer 15

acts as a binder, disintegrant or a dissolution enhancer

Question 16

what does gelatin do?

Answer 16

acts as a binder that swells upon hydration as it absorbs water.

Question 17

what are the two types of gelatin?

Answer 17

type A: acid hydrolysed

type B: alkali hydrolysed

Question 18

what is the first step in tablet dissolution and drug release?

Answer 18

disintegration

Question 19

how does disintegration affect the dissolution rate?

Answer 19

by increasing the particle surface area hence increases the dissolution rate.

Question 20

What is used to increase tablet disintegration?

Answer 20

disintegrants

Question 21

what are traditional disintegrants?

Answer 21

polymers that swell 2-dimensionally upon hydration

Question 22

what are superdisintegrants?

Answer 22

cross-linked polymers that swell 3-dimensionall upon hydration

Question 23

what are examples of superdisintegrants?

Answer 23

1. Sodium starch glycolate:cross-linked starch.
2. Croscarmellose: cross-linked carboxymethyl cellulose.
3. Crospovidone: cross-linked PVP

Question 24

what are effervescent disintegrants?

Answer 24

they produce gas upon hydration

Question 25

what do carbonates and bicarbonates break down into under acidic conditions?

Answer 25

carbon dioxide and water

Question 26

proposed mechanism of tablet disintegration is..?

Answer 26

1. swelling
2. wicking
3. strain recovery
4. heat of interaction
5. interruption of bonding forces
6. repulsion

Question 27

What happens during swelling?

Answer 27

• water uptake causes swelling and the degree of swelling depends on particle size and degree of cross-link.
• occurs in hydrophilic water-insoluble polymers.

Question 28

what is wicking?

Answer 28

when water is drawn into the tablet due to the formation of hydrophilic conduits (channel) in the tablet.

Question 29

what happens during strain recovery?

Answer 29

• particles undergo elastic deformation during tablet formation
• then are interblocked before they can relax.
• water in the tablet matrix causes particles to relax.
• particles then regain their original shape and force other particles away.

Question 30

what happens during heat of interaction?

Answer 30

• exothermic interactions release heat/energy during interactions with water.
• air that’s trapped in the tablet absorbs the energy and expands.

Question 31

what happens when bonding forces are interrupted?

Answer 31

bonds are weakened/interrupted due to aqueous environment causing dissolution and bonding with water molecules

Question 32

what is repulsion?

Answer 32

water uptake causes electrostatic repulsion between particles e.g. when particles are ionised in water.

Question 33

what are the commonly used lubricants?

Answer 33

1. magnesium stearate
2. stearic acid
3. talc

Question 34

most lubricants are what? hydrophobic or hydrophilic?

Answer 34

hydrophobic