Modified Release

Question 1

Advantages of Modified Release (5)

Answer 1

1. reduce problems with patient compliance
2. reduce the fluctuation of drug blood level
3. reduce dosing frequency
4. reduce local or system side effects
5. reduce overall health care costs

Question 2

Disadvantages of Modified Release (5)

Answer 2

1. dose dumping
2. less accurate adjustment (cant break tablet)
3. increase potential for first-pass metabolism
4. dependence on residence time in GI tract
5. delay onset

Question 3

Drug candidates suitable to modified release products (5)

Answer 3

1. neither very slow nor fast rates of absorption and excretion
2. uniform absorption from the GI tract
3. Small dose < 500 mg
4. wide therapeutic index/window
5. chronic disease condition

Question 4

5 Classes of Modified Release Systems

Answer 4

1. diffusion controlled system (monolithic and reservoir)
2. ion exchange resin system
3. osmotically controlled system
4. hydrodynamically balanced system
5. gemoetrically modified system

Question 5

What is the simplest and cheapest way to make a sustained release tablet?

Answer 5

Monolithic Controlled Matrix System

Question 6

3 types of matrices

Answer 6

1. water insoluble matrix
2. swellable matrix
3. biodegradable/ bioerodible matrix

Question 7

Advantages of water insoluble and swellable matrices (2)

Answer 7

1. easier to produce than reservoir devices

2. can deliver high mol. wt. compounds

Question 8

Disadvantages of water insoluble and swellable matrices (2)

Answer 8

1. cant obtain zero-order release

2. removal of remaining matric is necessary for implanted systems

Question 9

Why dont biodegradable polymers harm the body?

Answer 9

Because it is broken down to single molecule of lactic or glycolic acid (products of Kreb’s Cycle)

Question 10

Advantages of biodegradable matrices (2)

Answer 10

1. all the advantages of matrix system

2. removal from implant site isn’t necessary

Question 11

Disadvantages of biodegradable matrices (2)

Answer 11

1. difficult to control kinetics owing to multiple processes of release
2. potential toxicity of degraded polymer if not biodegradable

Question 12

Advantages of Reservoir controlled membrane system (2)

Answer 12

1. zero-order delivery is possible

2. release rate variable with polymer type and thickness

Question 13

Disadvantages of Reservoir controlled membrane system (3)

Answer 13

1. bad for high mol. wt. compounds
2. cost
3. potentially toxicity if system fails

Question 14

What is Ion Exchange Resin Matrix System?

Answer 14

ionic drugs will bind to the functional groups of the resin

Question 15

Advantages of Ion Exchange (2)

Answer 15

1. high drug loading

2. pH independent

Question 16

Disadvantages of Ion Exchange (2)

Answer 16

1. no zero-order release kinetics

2. severe tailing at later stage of release

Question 17

Advantages of Osmotically controlled system (3)

Answer 17

1. zero-order release is obtainable
2. reformulation isnt required for different drugs
3. release of drug is independent of environment of system

Question 18

Disadvantages of Osmotically controlled system (2)

Answer 18

1. system can be expensive

2. quality control is more extensive