Drug absorption Flashcards Preview

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Flashcards in Drug absorption Deck (35)
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1
Q

Pharmaceutical process

A

Get the drug into the patient

2
Q

Pharmacokinetic process

A

Get the drug to the site of action

3
Q

What are the four basic factors determine drug pharmacokinetics

A

Absorption
Distribution
Metabolism
Elimination

4
Q

Define absorption

A

the process of movement of unchanged drug from the site of administration to the systemic circulation

5
Q

What are the different routes drugs can be absorbed into the blood stream

A
Oral
Intravenous
Subcutaneous 
Intramuscular
Other GI - Sublingual, rectal
Inhalation
Nasal
Transdermal
6
Q

How does increasing the dose effect time and concentration

A

does not affect the time at which peak concentration is reached but does increase the peak concentration

7
Q

Does increasing the concentration of drug increase the rate of the reaction

A

no

8
Q

What is the therapeutic index

A

measure of the range at which a drug is safe and active

9
Q

What is the therapeutic range

A

A drug is active over a range of concentrations

10
Q

what is BIOAVAILABILITY

A

an estimate of the amount of drug which reaches the circulation and is available for action

11
Q

Which route of administration gives 100% bioavailability

A

IV

12
Q

What are the factors affecting bioavailability

A

Formulation
Ability of drug to pass physiological barriers
Gastrointestinal effects
First pass metabolism

13
Q

Define desolation

What is modified release

A

when the drug breaks up

Slow release of drugs passing from GI tract

14
Q

The ability of drugs to pass physiological barriers is dependant on drugs

A

Particle size
Lipid solubility
pH and ionisation

15
Q

What are the different methods drugs are transported across the membrane

A
Passive diffusion
Filtration
Bulk flow
Active transport
Facilitated diffusion
Ion-pair transport
Endocytosis
16
Q

What kind of drugs cant cross membrane

A

ionised drugs as aren’t lipid soluble

17
Q

Where is an acidic drug more likely to be trapped

A

compartment with high pH

18
Q

Changing the pH of an environment can alter the ionisation of the drug affecting the rate of

A

absorption or diffusion

19
Q

The ability of a drug to diffuse across a lipid barrier is expressed as a

A

lipid-water partition coefficient

20
Q

To undergo active transport drugs must resemble

A

naturally occurring compounds

21
Q

How does bulk flow transport occur

A

Occurs through channels in the cell membrane and is dependant on the blood flow

22
Q

What is the driving force of bulk flow

A

driving force for the passage of the drugs is the hydrostatic or the osmotic pressure difference across the membrane

23
Q

What Gastrointestinal Factors effect drug absorption

A

Motility - speed of gastric absorption
Food - enhance or impair absorption
Illness - eg diarrhoea, drugs go straight through you
or some illnesses will enhance absorption

24
Q

Define first pass metabolism

A

Metabolism of drug prior to reaching systemic circulation

25
Q

What route can avoid first pass metabolism

A

IV
Sublingual
Rectal
transdermal

26
Q

What does a migraine reduce

A

the rate of stomach emptying therefore decreasing absorption rate

27
Q

What are the benefits of IV

A

needs small volume
can change the rate of absorption from sites with physical properties
gives 100% bioavailability
Avoids first pass metabolism

28
Q

What administration route allows drugs to enter circulation directly

A

sublingual

29
Q

What is an advantage and disadvantage of rectal administration

A

dis - absorption tends to be slow

adv- prevent drugs causing irritation of the stomach

30
Q

Where will inhalation administration be metabolised

A

in the lungs

31
Q

When is inhalation usually used

A

topical effect
avoid problems of oral absorption (eg nausea)
for rapid action

32
Q

What is an advantage and disadvantage of transdermal

A

adv - provides a controlled release

dis - few substances are well absorbed

33
Q

Considerations for mode of administration

A
Purpose and site of drug action
  -Local absorption
  -Avoid first pass metabolism
Disease effects
Patients ability to take medicine
Speed of action
Reliability of absorption
34
Q

What can cause local metabolism

A

Sublingual
Inhalation
rectal

35
Q

Where are drugs absorbed from

A

GI tract

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