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Medicine Term One > Drug absorption > Flashcards

Flashcards in Drug absorption Deck (35):
1

Pharmaceutical process

Get the drug into the patient

2

Pharmacokinetic process

Get the drug to the site of action

3

What are the four basic factors determine drug pharmacokinetics

Absorption
Distribution
Metabolism
Elimination

4

Define absorption

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

5

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

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

6

How does increasing the dose effect time and concentration

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

7

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

no

8

What is the therapeutic index

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

9

What is the therapeutic range

A drug is active over a range of concentrations

10

what is BIOAVAILABILITY

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

11

Which route of administration gives 100% bioavailability

IV

12

What are the factors affecting bioavailability

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

13

Define desolation
What is modified release

when the drug breaks up
Slow release of drugs passing from GI tract

14

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

Particle size
Lipid solubility
pH and ionisation

15

What are the different methods drugs are transported across the membrane

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

16

What kind of drugs cant cross membrane

ionised drugs as aren't lipid soluble

17

Where is an acidic drug more likely to be trapped

compartment with high pH

18

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

absorption or diffusion

19

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

lipid-water partition coefficient

20

To undergo active transport drugs must resemble

naturally occurring compounds

21

How does bulk flow transport occur

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

22

What is the driving force of bulk flow

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

23

What Gastrointestinal Factors effect drug absorption

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

Define first pass metabolism

Metabolism of drug prior to reaching systemic circulation

25

What route can avoid first pass metabolism

IV
Sublingual
Rectal
transdermal

26

What does a migraine reduce

the rate of stomach emptying therefore decreasing absorption rate

27

What are the benefits of IV

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

28

What administration route allows drugs to enter circulation directly

sublingual

29

What is an advantage and disadvantage of rectal administration

dis - absorption tends to be slow
adv- prevent drugs causing irritation of the stomach

30

Where will inhalation administration be metabolised

in the lungs

31

When is inhalation usually used

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

32

What is an advantage and disadvantage of transdermal

adv - provides a controlled release
dis - few substances are well absorbed

33

Considerations for mode of administration

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

What can cause local metabolism

Sublingual
Inhalation
rectal

35

Where are drugs absorbed from

GI tract