drug absorption

Question 1

what is the pharmaceutical process?

Answer 1

getting the drug to the patient

Question 2

what is the pharmacokinetic process?

Answer 2

getting the drug to the site of action

Question 3

what is the pharmacodynamic process?

Answer 3

producing the correct pharmacological effect

Question 4

what is the therapeutic process?

Answer 4

producing the correct therapeutic effect

Question 5

what does ADME stand for and what does it determine?

Answer 5

Absorption
Distribution
Metabolism
Elimination
these factors determine drug pharmacokinetics

Question 6

what routes of administration are there for drugs?

Answer 6

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

Question 7

why do drugs have to be absorbed to be effective?

Answer 7

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

Question 8

what is the Tmax?

Answer 8

time taken for the drug to reach peak concentration

Question 9

what is the Cmax?

Answer 9

the peak concentration of the drug

Question 10

what is the AUC?

Answer 10

area under the drug concentration/time curve on a graph

Question 11

what does the AUC represent?

Answer 11

the amount of drug which reaches the systemic circulation

Question 12

what does a high tmax indicate?

Answer 12

high rate of absorption

Question 13

what is the therapeutic range?

Answer 13

the range of concentrations over which a drug is active

Question 14

what is the therapeutic index?

Answer 14

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

Question 15

what is drug bioavailability?

Answer 15

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

Question 16

how much of a drug given intravenously is bioavailable?

Answer 16

100%

Question 17

what are some factors affecting bioavailability?

Answer 17

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

Question 18

do drugs completely ionise in water?

Answer 18

not usually, some exceptions

Question 19

what does the degree of ionisation depend on?

Answer 19

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

Question 20

can the ionised form of a drug cross a membrane?

Answer 20

no

Question 21

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

Answer 21

when equilibrium is released

Question 22

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

Answer 22

lipid-water partition coefficient

Question 23

what is the lipid water partition coefficient?

Answer 23

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

Question 24

what is first pass metabolism?

Answer 24

metabolism of drug prior to reaching systemic circulation

Question 25

what things can affect first pass metabolism?

Answer 25

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

Question 26

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

Answer 26

avoids first pass metabolism

Question 27

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

Answer 27

avoids first pass metabolism

GTN spray

Question 28

when would rectal administration of a drug be considered?

Answer 28

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

Question 29

what are the advantages of inhalation of a drug?

Answer 29

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

Question 30

what are the advantages of transdermal application of a drug?

Answer 30

avoids first pass metabolism

can provide controlled release

Question 31

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

Answer 31

needs to be non irritant

Question 32

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

Answer 32

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