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Flashcards in drug absorption Deck (27)
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1

four basic factors which determine drug pharmacokinetics

-absorption
-distribution
-metabolism
-elimination

2

ways of drug administration

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

3

drug absorption

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

4

Tmax

the time to peak concentration

5

Cmax

the peak concentration

6

AUC

area under the drug concentration curve

7

what does AUC tell us?

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

8

therapeutic range

the range of concentrations over which a drug is effective

9

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

there will be insufficient or no pharmacological action

10

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

toxicity

11

therapeutic index

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

12

bioavailability

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

13

what is the bioavailability of a drug given intravenously?

100%

14

factors affecting bioavailabilty (oral absorption)

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

15

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

-particle size
lipid solubility
-pH and ionisation

16

gastrointestinal effects that effect bioavailability

- gut motility
- food
- illness

17

first pass metabolism

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

18

physiological barriers

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

19

Henderson-Hasselbalch equation

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

20

where will highly lipid soluble drugs collect?

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

21

lipid-water partition coefficient

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

22

what must a drug resemble to undergo active absorption?

naturally occurring compounds

23

bulk flow

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

24

filtration

drugs move through channels in cell membrane

25

gastrointestinal factors that affect drug absorption

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

26

sites of first pass metabolism

Liver
gut wall
gut lumen

27

ways of administration that bypass first pass metabolism

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