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Flashcards in drug absorption Deck (32):
1

what is the pharmaceutical process?

getting the drug to the patient

2

what is the pharmacokinetic process?

getting the drug to the site of action

3

what is the pharmacodynamic process?

producing the correct pharmacological effect

4

what is the therapeutic process?

producing the correct therapeutic effect

5

what does ADME stand for and what does it determine?

Absorption
Distribution
Metabolism
Elimination
these factors determine drug pharmacokinetics

6

what routes of administration are there for drugs?

oral
IV
subcutaneous
intramuscular
other GI - sublingual, rectal
inhalation
nasal
transdermal

7

why do drugs have to be absorbed to be effective?

they have to enter the bloodstream and make their way to the potential site of action

8

what is the Tmax?

time taken for the drug to reach peak concentration

9

what is the Cmax?

the peak concentration of the drug

10

what is the AUC?

area under the drug concentration/time curve on a graph

11

what does the AUC represent?

the amount of drug which reaches the systemic circulation

12

what does a high tmax indicate?

high rate of absorption

13

what is the therapeutic range?

the range of concentrations over which a drug is active

14

what is the therapeutic index?

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

15

what is drug bioavailability?

the amount of drug which reaches the circulation AND which is available for action

16

how much of a drug given intravenously is bioavailable?

100%

17

what are some factors affecting bioavailability?

formulation
ability of drug to pass physiological barriers (particle size, lipid solubility, pH and ionisation)
GI effects (gut motility, food, illness)
first pass metabolism

18

do drugs completely ionise in water?

not usually, some exceptions

19

what does the degree of ionisation depend on?

the pH of the environment, since most drugs are weak acids or bases

20

can the ionised form of a drug cross a membrane?

no

21

what would stop the un-ionised form of a drug from diffusing across a membrane?

when equilibrium is released

22

what is the ability of a drug to diffuse across a lipid barrier expressed as?

lipid-water partition coefficient

23

what is the lipid water partition coefficient?

ratio of the amount of drug which dissolves in the lipid and water phase when they are in contact

24

what is first pass metabolism?

metabolism of drug prior to reaching systemic circulation

25

what things can affect first pass metabolism?

gut lumen (acid, enzymes)
gut wall (metabolic enzymes)
liver (hepatic extraction ratio)

26

what advantages are there to sub-cutaneous/intra muscular administration?

avoids first pass metabolism

27

what advantages are the of sublingual/buccal administration and give an example of a drug administered this way

avoids first pass metabolism
GTN spray

28

when would rectal administration of a drug be considered?

if a drug irritates the stomach (absorption is slow and avoids first pass metabolism)

29

what are the advantages of inhalation of a drug?

rapid action -delivered directly to site of action in case of asthma, for example
better for volatile agents

30

what are the advantages of transdermal application of a drug?

avoids first pass metabolism
can provide controlled release

31

what conditions need to be met for a drug to be given transdermally?

needs to be non irritant

32

what considerations would be mode prior to deciding which mode of administration to take?

purpose and site of drug action
disease effects
patient ability to take medicine
speed of action
reliability of absorption