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Flashcards in Modified release oral drug delivery Deck (19)
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1
Q

What are the advantages of modified release drugs?

A

Peaks and troughs are minimised
Improved compliance
Lower side effects
Less drug used

2
Q

What is meant by a delayed release formulation?

A

The drug is not released immediately, but at a later time

3
Q

What is meant by a repeat action delivery system?

A

A dose is released on administration, second and third doses are released at later intervals

4
Q

What is meant by a prolonged release delivery system?

A

The drug is absorbed over a longer period of time than from a conventional dosage form.

5
Q

What is meant by a sustained action delivery system?

A

An initial release of drug that is sufficient to provide a therapeutic dose soon after administration, then a gradual release over an extended period

6
Q

What is meant by an extended release drug delivery system?

A

Slow release of the drug

7
Q

What is meant by controlled release of the drug?

A

Release of drug at a constant rate and provides plasma concentrations that remain invariant with time

8
Q

What is the difference between drug release from a hydrophilic matrix and a membrane controlled delivery system?

A

In a hydrophilic matrix, the colloids swell in contact with water to form a hydrated matrix which controls the further diffusion of water into the matrix and this controls the rate of release of drug.
In a membrane controlled delivery system, there is no swelling on hydration of the membrane and the membrane does not erode.

9
Q

How do osmotically-controlled systems work?

A

Osmotic pressure is used as the driving force to generate a constant rate of drug release. The membrane permits the passage of GI fluid, but not drug or electrolyte

10
Q

In an osmotically-controlled system, what is the rate of drug release governed by?

A

The rate at which water is able to pass through the membrane and how fast drug solution can pass out

11
Q

First order release is what you want to achieve with modified release systems. True or false?

A

False - zero order

12
Q

The main purpose of using an oral delayed release tablet is to prolong the half life of a drug. True or false?

A

False - to provide site-specific absorption of drug

13
Q

How does microencapsulation alter the release of tablet?

A

Simply coating (e.g. by spray) the surface of a drug particles with polymer to slow down water penetration and hence dissolution

14
Q

How do ion exchange resins alter the release of drugs?

A

Ionised drug binds to a polymeric resin through opposite charges.
Drug resin is then milled to obtain a smaller particle size

15
Q

Which ion exchange resins do basic drugs bind to?

A

Cationic exchange resins

16
Q

Which ion exchange resins do acidic drugs bind to?

A

Anionic exchange resins

17
Q

How do KCl extended release tablets work?

A

Each crystal of KCl is microencapsulated with an insoluble polymeric semi-permeable membrane
As fluids pass through the membrane KCl dissolvese within the microcapsules and is released through the membrane over 8-10 hours

18
Q

Which causes more gastric irritation slowK or MicroK?

A

Slow K

19
Q

How do MST continus suspension granules work?

A

Morphine bound to ion exchange resin beads

Morphine is displaced by sodium and potassium ions present throughout the GIT