How drugs act P2 L14

Question 1

pharmacokinetics=

Answer 1

factors that determine the active concentration of the drug at the active site

Question 2

absorption=

Answer 2

the mechanism of accumulation of a drug in a body compartment following administration

Question 3

distribution=

Answer 3

the way in which a drug reaches each organ of the body

Question 4

metabolism=

Answer 4

the chemical alteration of a drug into its inactive form

Question 5

excretion=

Answer 5

removal of a drug and/or its metabolites from the body

Question 6

what factors determine the conc of a drug at its active site

Answer 6

ADME
absorption 
distribution 
metabolism 
excretion

Question 7

when would a drug be ionised

Answer 7

when pH is opposite to pKa

Question 8

what drugs can’t dissolve through the lipid membrane

Answer 8

ionised acid and bases

Question 9

what plasma protein do drugs bind to (especially warfarin)

Answer 9

albumin

Question 10

what is a bound drug

Answer 10

inactive

Question 11

what determines distribution of free drugs

Answer 11

lipophilicity

Question 12

Volume of distribution (Vd)=

Answer 12

theoretical volume that the total amount of drug would have to occupy (if uniformly distributed) to provide the same concentration as is currently in blood plasma

Question 13

when is Vd low

Answer 13

if drug restricted to plasma water (ionised)-7000mls

Question 14

when is Vd equal to body volume

Answer 14

if lipophillic - 70,000

Question 15

when is Vd high

Answer 15

if protein bound 350,000mls

Question 16

where is the principal site for drug metabolism

Answer 16

the liver

Question 17

what is a prodrug

Answer 17

an inactive or weakly active substance that has active metabolites

Question 18

where does the liver filter blood directly from

Answer 18

the small intestine

Question 19

whats it called when the liver first filters blood from the small intestine

Answer 19

first pass effect

Question 20

what happens in phase 1 metabolism

Answer 20

drug is made more polar by oxidation, hydroxylation, deamination, hydrolysis

Question 21

what haem protein does first phase effect involve

Answer 21

cytochrome P450

Question 22

what do cytochromes do (2)

Answer 22

Induction (decreased drug activity)

Inhibition (increases the activity of a drug)

Question 23

what happens in phase 2 metabolism

Answer 23

conjugation

Question 24

examples of substances use to conjugate drugs (2)

Answer 24

sulphuric acid

Glucuronic acid

Question 25

what is conjugation

Answer 25

combining the drug with another chemical

Question 26

what does conjugation achieve

Answer 26

makes it more polar and less reactive —> easily secreted

Question 27

where are drugs excreted (3)

Answer 27

Urine
faeces
lungs

Question 28

what 2 factors affect drug absorption

Answer 28

pH

lipophilicity

Question 29

elimination half life=

Answer 29

time taken for Cmax to fall by 50%

Question 30

Cmax=

Answer 30

maximum plasma concentration following a given dose

Question 31

Tmax=

Answer 31

time taken between drug dose and achieving Cmax