drug absorption

Question 1

four basic factors which determine drug pharmacokinetics

Answer 1

• absorption
• distribution
• metabolism
• elimination

Question 2

ways of drug administration

Answer 2

• oral
• IV
• subcutaneous
• intramuscular
• sublingual (under the tongue)
• rectal
• inhalation
• nasal
• transdermal eg, with patches

Question 3

drug absorption

Answer 3

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

Question 4

Tmax

Answer 4

the time to peak concentration

Question 5

Cmax

Answer 5

the peak concentration

Question 6

AUC

Answer 6

area under the drug concentration curve

Question 7

what does AUC tell us?

Answer 7

the amount of drug which reaches the systemic circulation (bioavailability)

Question 8

therapeutic range

Answer 8

the range of concentrations over which a drug is effective

Question 9

what happens if a drug conc. is below the therapeutic range?

Answer 9

there will be insufficient or no pharmacological action

Question 10

what happens if a drug conc. is above the therapeutic range?

Answer 10

toxicity

Question 11

therapeutic index

Answer 11

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

Question 12

bioavailability

Answer 12

the amount of drug that reaches the circulation and is available for action

Question 13

what is the bioavailability of a drug given intravenously?

Answer 13

100%

Question 14

factors affecting bioavailabilty (oral absorption)

Answer 14

• formulation- preparations that might cause a slow release
• ability of drug to pass physiological barrier
• gastrointestinal effects
• first pass metabolism

Question 15

factors that affect a drug’s ability to pass physiological barriers

Answer 15

-particle size
lipid solubility
-pH and ionisation

Question 16

gastrointestinal effects that effect bioavailability

Answer 16

• gut motility
• food
• illness

Question 17

first pass metabolism

Answer 17

the metabolism of drugs rapidly by liver before it reaches the systemic circulation

Question 18

physiological barriers

Answer 18

• passive transport
• filtration
• bulk flow
• active transport
• facilitated diffusion
• ion-pair transport
• endocytosis

Question 19

Henderson-Hasselbalch equation

Answer 19

describes the relationship between the local pH and the degree of ionisation

Question 20

where will highly lipid soluble drugs collect?

Answer 20

brain, ovaries, testes and liver. so levels of the drug above the therapeutic range will cause damage in these places.

Question 21

lipid-water partition coefficient

Answer 21

The ability of a drug to diffuse across a lipid barrier. the ratio of the amount of drug which dissolves in the lipid and water phase when they are in contact

Question 22

what must a drug resemble to undergo active absorption?

Answer 22

naturally occurring compounds

Question 23

bulk flow

Answer 23

the movement of water and solute due to a pressure gradient.

Question 24

filtration

Answer 24

drugs move through channels in cell membrane

Question 25

gastrointestinal factors that affect drug absorption

Answer 25

-motility
-food
illness (malabsorption, migraine reduces rate of stomach emptying so absorption decreases as drug doesn’t make it to small intestine as fast)

Question 26

sites of first pass metabolism

Answer 26

Liver
gut wall
gut lumen

Question 27

ways of administration that bypass first pass metabolism

Answer 27

• IV
• intra-muscular
• subcutaneous
• sub-lingual
• sub-buccal
• rectal
• transdermal