MRDF Flashcards

1
Q

Based on the conventional release profile, what are the challenges you identify for drug action?

A

conventional dosage forms do not maintain blood concentration within therapeutic range for extended period of time and
controllable drug release is not possible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What does MEC?

A

minium effective concentration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is MTC?

A

Minimum toxic concentration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

if drug level have to be maintained using conventional dosage forms what are the two approaches?

A

increase initial dose to increase duration of actions
administer the drug repeatedly using a constant dosing interval

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the consequence of increasing initial dose?

A

increase potential of toxicity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the consequence of repeated drug administration

A

missed doses or
made up doses or
pt non-compliance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the rationale for MRDFs?

A

to prolong or control drug availability or release with the intent of improving efficacy of drug therapy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the two major types of MRDFs?

A

delayed action
extended action

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Define delayed action

A

lag period between admin. and release
release the drug at particular site
mostly enteric coated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Define extended action

A

release the medication in a controlled manner at a predetermined rate, duration and location to achieve and maintain therapeutic blood levels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What does sustained release systems include?

A

any drug delivery system that achieves slow release of drug over extended period of time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is needed to consider it a controlled release system?

A

if a sustained release system is successful at maintaining constant drug levels in the target organs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is needed to consider it a prolonged release system?

A

prolongs therapeutic levels of the drugs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the purpose of extended release systems?

A

allows reduction in dosing frequency

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the purpose of delayed release systems?

A

it can release the drug at a time other than promptly after administration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Define targeted release

A

isolates or contrates the drugs in specific body region, tissue or organ

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is an example of targeted release?

A

tumor nanomedicine - targeted drug delivery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what is repeat action?

A

forms usually contain two or more single doses of the drug, one for immediate release and the second for delayed release

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the examples for preparing delayed action formulation?

A

entric coated
rheumatoid action
morning sickness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the rationale for extended release?

A

provides an immediate release, giving the effect now as well as by the gradual and continual release of additional amounts of drug

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

T/F Controlled release are therefore extended release formulations

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the difference between SR and XL?

A

it is different in the duration of action

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

List somes advantages of MRDFs

A

less fluctuation of drug levels
reduced dosing frequency
enhanced pt compliance
reduction in A/E
reduced in health care cost

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

List some limitations of MDFS

A

costly
immediate termination of drug action is not possible
contains higher drug amounts (abuse potential)
drug excipient interaction
more complicated formulation design
not suitable for rapid action (Emergency use)
not flexible (cannot split)

25
Q

To have the equvient dose how many doses in the day with IR, SR and XR

A

IR - TID
SR - BID
XR - Once daily

26
Q

List the variables in the design

A

route of delivery
type of delivery system
disease being treated
the patient
length of therapy
properties of the drug (physicochem/bio)

27
Q

What factors are considered when the drug has low water solubility?

A

longer time to dissolve in GI fluids
slower absorption
inherently extended release

28
Q

What factors are considered when the drug has high water solubility?

A

difficult to reduce their dissolution rate to an acceptable range

29
Q

Define partition coefficient

A

potential of drugs to cross biological membrane

30
Q

What does partition coefficient affect?

A

the ability of the drugs to diffuse through the polymers used in the design of MRDFs

31
Q

What two factors need to be balanced with stability>

A

the stability of the drug inside and outside of the body

32
Q

Explain the slow kinetics

A

inherently long acting
not necessary to prepare MRDFs

33
Q

Explain the fast kinetics

A

very short half lives
very large amounts will be required to design MRDF

34
Q

What are the two factors need to look at for rate of absorption and excretion?

A

slow kinetics or fast kinetics

35
Q

Explain the ability of drugs for complexation

A

drugs which show high levels of protein binding in the blood are not suitable for MRDFs

36
Q

T/F Only free unbound drugs can diffuse through tissues and hence can be controlled

A

True

37
Q

What needs to be looked at for a good margin of safety?

A

therapeutic window –> it can not be narrow as it has a risk of dose dumping if the product is defective or incorrectly administered

38
Q

Should MRDFs be used for chronic conditions or acute? Why?

A

acute –> as more dosage adjustments are required
and immediate use of the medications

39
Q

What should be considered for dosing for MRDFs?

A

If conventional formulation has a large dose  larger sized tablets and capsules required to design MRDFs difficult swallowing  reduced patient compliance

40
Q

What is the max dose for oral formations?

A

0.5-1 gram

41
Q

List the mechanisms for modified release

A

membrane dissolution
membrane diffusion
matrix dissolution
matrix diffusion
membrane-matrix hybrids
osmotic pressure

42
Q

What categories do most products fall into?

A

membrane dissolution systems
matrix dissolution systems

43
Q

Define dissolution systems

A

Controlled release products are prepared by controlling the dissolution rate of drugs that are readily soluble.

44
Q

T/F uncoated particles = immediate release form of drugs

A

True

45
Q

Explain the two types of membrane dissolution systems

A

different groups of particles with different membrane thickness and composition are made, that will release the drug at different rates or times.

a layer of drug is coated by sugar core
then coated with slowly dissolving membrane
another layer of drug that another coat
(the outer layer is the loading dose)

46
Q

Explain Layered tablets

A

Layered technology
Immediate burst and prolonged release  layered dissolution

47
Q

Explain matrix dissolution systems

A

drug is dispersed in a series of different size granules
the different size will have different dissolution times

48
Q

What are two types of diffusion systems?

A

membrane diffusion
matrix diffusion

49
Q

Explain diffusion systems

A

release rate of drug is determined by its diffusion through a water insoluble polymer

50
Q

Explain membrane diffusion

A

core is surrounded by a polymeric membrane
reservoir devices

51
Q

Explain matrix diffusion

A

drugs is distributed uniformly in an inert polymeric matrix
matrix device

52
Q

Explain how reservoir devices

A

drug release usually involves
- dissolution of drug inside the reservoir
- diffusion of drug across membrane - rate controlling step

53
Q

What is the rate limiting step with matrix diffusion devices?

A

diffusion of the drug from the matrix to outside

54
Q

Explain how a matrix diffusion device works

A

drug is dispersed homogeneously in the matrix which does not dissolve or erode

55
Q

What are some examples of membrane-matrix hybrid?

A

mirena IUD
nuva ring

56
Q

Define osmotic systems

A

it uses osmotic pressure can be employed as the driving force to generate a constant release of drug, provided that constant osmotic pressure is maintained

57
Q

Explain how osmotic pressure works to help with MDRFs

A

Water moves in –> dissolves or suspends the drug –> membrane is not permeable to the drug –> the system pushes the drug out through the orifice

58
Q

What are some counselling points for MRDFs?

A
  • Advise the patients of the dose and dosing frequency of modified drug release products
  • Advice the patients not to use them interchangeably with immediate release of the same drug
  • Patients stabilized on a modified-release product should not be changed to an immediate release product
  • Once stabilized, patients should not be changed to another extended-release product unless there is assurance of equivalent bioavailability.
  • capsules should not be crushed or chewed
  • pt fed by an NG feeding tube may receive conventional or modified release
  • empty shells may be seen in the stool