Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Pharm202 > Lecture 15 > Flashcards

Lecture 15 Flashcards

1
Q

What is drug release?

A

the process by which the drug leaves a drug product and is subjected to absorption

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

What is drug release also achieved by?

A

diffusion

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

what controlls drug release?

A

the physicochemical properties of the drug, delivery system, biological system and physiological properties of the biological system
E.g. PH of the stomach different from intestine, the Physical properties of some places are not idea for absorption

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

What is the process of drug release?

A

the drug first has to go from the solid state to the solution and then the drug molecules can diffuse out.
For some liquid drugs, dissolution is not necessary but it still has to diffuse out from the matrix

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

What happens to the flux if the concentration gradient is bigger?

A

the flux is also bigger

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

what direction does diffusion occur in?

A

from an area of high concentration to one of low concentration

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

Why do we have many different dosage forms?

A

we cant directly give the drug powder to the patient as we have to make it useful and easy for the patient to take

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

what are some of the dosage forms we have for drugs?

A

tablets, capsules, solutions, injections etc

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

what is a dosage form made up of mainly?

A

the active ingredient + excipients/additives

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

what are exicipients/additives?

A

the inactive ingredients. e.g. polymers

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

What do we have to consider when making the dosage form?

A 
stability
reliability
predictability
Reproducibility
effectiveness
convenience
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what are the essential properties of a medicine?

A

quality
efficacy
safety

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

What do we need to consider when DESIGNING a dosage form?

A

Portal of drug entry
Physical form of drug product
Design and formulation of product
Method of manufacture: scale up
Various physicochemical properties of drug and excipients
Control and maintenance of the drug product at the target site e.g. Targeting to the colon, bio adhesive

All of this relies on the control of drug release

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

Why is modified drug release used?

A

It allows a controlled administration of the dose at a desired rate of delivery

we can keep drug concentration in the plasma for longer, and it will be safer as it will achieve an optimal concentration

we can alter the half life so the drug doesnt have to be taken as much

It may also reduce adverse effects

can also lead to enhancement of patient compliance

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

What are some issues with unmodified released drugs?

A

if it is quickly released, might cause a problem if it overshoots the required concentration for therapeutic benefit

may also have a short half life

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

What are the different types of modified release dosage?

A 
delayed release
repeat action
prolonged release
sustained release
extended release
controlled release
17
Q

What is delayed release?

A

drug released after a lapse of time and not immediately. E.g. If the drug should not be exposed to acid. We want a delay in the release so that it has passed through the stomach so the environment is not as acidic

18
Q

What is repeat action release?

A

Individual dose is released as soon as drug is administered and subsequent doses released and intermittent intervals

19
Q

What is prolonged release?

A

Drug is provided for absorption over a long period of time

20
Q

What is sustained release?

A

Initial release is sufficient to produce a therapeutic response and then the blood levels maintained by slow release over a period.

21
Q

What is extended release?

A

Drug is released slowly so that plasma concentrations are maintained over a prolonged period of time

22
Q

What is controlled release?

A

drug release is designed at a constant rate to provide plasma concentrations which do not vary with time.

23
Q

what makes up the largest portion of the pharmaceutical industry?

A

controlled release societ

24
Q

Why are polymers used?

A

Polymers can be used to form a matrix and embed a drug.
This allows us to modify the drug release as desired
We can provide enteric coatings of the drug
It allows us to achieve a targeting deliver

25
Q

How do we control drug release?

A

layers and heights of polymers

26
Q

What can we design the polymer to do?

A

We can design the polymer so they are pH sensitive so they can release the drug when the pH changes

27
Q

What is the basis of our use for polymers?

A

diffusion.

We use the polymer to control the release by controlling the drug diffusion.
Remember you can change the diffusion rate by changing viscosity

We can also encapsulate the drug capsules by using a polymer. (Enteric coatings)
The capsule is a membrane which controls the diffusion rate so that the drug is released by control

28
Q

How are polymers chosen?

A

First we consider the molecular weight, if its bigger, the viscosity will be bigger

Polymers are also normally crosslinked. The bigger the degree of cross linking, the slower the diffusion

Whether the polymer is in crystal form or not also places a small effect

29
Q

Describe the structure of an osmotic pump

A

The outside is coated with a drug. When this layer is explosed to water or liquid it causes the drug to give immediate release so the drug is readily absorbed

inside there is a similar layer which is semipermeable, this allows water to enter the tablet’s core

Once water gets in the NaCl gets dissolved, causing the volume to increase.
Once the pressure reaches the threshold, this will start to be pumped out.
By controlling the size of osmotically active concentration, we can control the release

30
Q

What is a homogenous matrix?

A

matrix made from polymer which allows the drug to be diluted equally from all directions

31
Q

How are heterogenous matrices formed?

A

by putting granules together

32
Q

what do heterogenous matrices do to the drug?

A

it gives the drug a tortuous path which allows us to control the release

it also has pores which liquid enters and allows the drug to leach out

33
Q

What are the 3 processes that occur when the polymer matrix (hetergenous matrix) is exposed to the aqueous environment?

A
  1. Water will diffuse in
  2. The drug will start dissolution
  3. The drug will diffuse out from this channel or pore or from the surface of the homogenous matrix
34
Q

How does a drug behave in a polymer/heterogenous matrix?

A

Some of the drug will dissolve into molecules. when placed in an aqueoues environment, the dissolved molecles will be first to diffuse out

this forms a depletion zone where diffusion continues simultatneously

around the matrix we have a static diffusion layer. If we consider perfect sink conditions like our stomach, it is quickly absorbed

This means the drug concentration in the environment is quickly reduced to a small concentration
Next to the matrix, the maximum concentration it can reach is the solubility.
Over time the depletion layer is formed, however some drugs are still solid
There’s always a boundary.
When Continuing the depletion zone, we can see that The matrix decreases with time

35
Q

Why can fick’s first law equation be simplified to just Cs/h?

A

the Cs is much her than the C due to sink conditions, the drug is removed very quickly

36
Q

What is dQ/dT?

A

the rate of drug released per unit area of exposed surface of the matrix per unit time

37
Q

What is the higuchi equation?

A

very important

the equation is a function of time as time is the only variable in the equation, everything else is constants

38
Q

What does the higuchi equation describe?

A

drug release:
if you have a high concentration of the drug in the matrix, you have quick drug release

It describes the release from homogenous polymer matrix type delivery system. It also applies for the release from emulsions, ointments

39
Q

How do you work out the release rate from the higuchi equation?

A

look at the release amount,
measure the drug released to the medium
calculate mass and record the mass released

convert time to its square root to get a straight line

then work out the release rate

Pharm202 (22 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions