Tricky topic pt 4

Question 1

if a drug is ionised how can it pass the membrane

Answer 1

via solute carriers (SLC)

Question 2

types of SLC

Answer 2

Organic cation transporters

Organic anion transporters

–> lots in proximal tubule

Question 3

bioavailability equation

Answer 3

F= the amount reaching systemic circulation / total drug given IV

Question 4

volume of distribution

Answer 4

drug dose / [plasma drug]

Question 5

body compartments

Answer 5

plasma

interstitial

intracellular

Question 6

excretion via the kidneys

Answer 6

1) glomerular filtration
2) proximal secretion
3) distal tubular reabsorption

Question 7

codeine converted to

Answer 7

morphine –> stronger agonist

Question 8

what do phase I enzymes do to drug

Answer 8

oxidation and reduction reactions

Question 9

what do phase II enzymes do to the druyg

Answer 9

sulphation

N-acetylation

Question 10

HRH

Answer 10

reduced functional reserve

Question 11

CYP450 can be

Answer 11

inducted or inhibited

Question 12

CYP450 induction

Answer 12

increased CYP450 (e.g. high translation rate) means that the drug gets metabolised too quickly (inactive) and decreases plasma conc- doesnt have desired therapeutic effect

Question 13

example of drug that can cause induction

Answer 13

CBZ- antiepiletic

Question 14

CYP450 inhibition

Answer 14

not enough CYP450 to metbaolise drug = high plasma conc, increase dtherpaetuic effect

Question 15

example of CYP450 inhibition

Answer 15

grapefruit

Question 16

proximal tubule has high expression of

Answer 16

OATs and OCTs

Question 17

urine pH

Answer 17

6-7.5

Question 18

muscularis externa in GI - inner

Answer 18

circular

Question 19

muscularis externa in GI - outer

Answer 19

longitudinal

Question 20

muscularis externa- stomach

Answer 20

oblique
circular
longitudinal

Question 21

muscularis externa in bladder

Answer 21

opposite way round

Question 22

clearance

Answer 22

the vol of plasma cleared of drug/ unit time

ml/m

Question 23

body clearance =

Answer 23

hepatic clearance and renal clearance

Question 24

first order drugs

Answer 24

cleared proportional to concentration

• predictable
• enough enzyme to clear

Question 25

shape of graph for first order drugs

Answer 25

linear

Question 26

zero order is

Answer 26

non proportional and therefore non predictable (half life)

Question 27

shape of graph for zero order drugs

Answer 27

non linear

Question 28

why are zero order drugs non proportional

Answer 28

reliant on functional reserve of enzymes

Question 29

who should not take zero order drug

Answer 29

those who lack functional reserve

• elderly and young
• HRH
• polypharmacy