Pharmacology

Question 1

What is First pass metabolism?

Answer 1

drug is absorbed through the enteral route and metabolised in the liver before it reaches systemic circulation

Question 2

What does a first order of drug metabolism mean?

Answer 2

Constant fraction of drug is metabolised

This rate of reaction does not saturate

Question 3

What does a zero order of drug metabolism mean?

Answer 3

Constant amount is metabolised

This means that this reaction can be saturated, as [drug input] increases

Question 4

During which [EtOH] is the metabolism a first order reaction?

Answer 4

<10mg/dL

Question 5

During which [EtOH] is the metabolism a zero order reaction?

Answer 5

> 10mg/dL

Question 6

At what rate is EtOH metabolised?

Answer 6

1 unit/hr

Question 7

What is the half life of a drug?

Answer 7

time taken for 50% of drug to be metabolised

Question 8

What is the function of phase I drug metabolism in the liver?

Answer 8

makes drug more polar/water soluble

Makes a reactive site in the molecule for conjugation to occur

Question 9

Which types of reaction occur predominantly in phase 1?

Answer 9

hydrolysis

REDOX

Question 10

Which enzymes catalyse phase 1 reactions?

Answer 10

Oxidation: cytochrome P450 monoxygenases
hydrolysis: esterases or proteases

Question 11

What are the 3 potential outcomes of a phase 1 reaction?

Answer 11

produce an active metabolite
produce a toxic metabolite
drug inactivation

Question 12

What are the outcomes of phase II reactions?

Answer 12

conjugation of metabolites/drugs to generate water soluble compounds that can be renally excreted

Question 13

What are the 5 main ways that drugs may be conjugated in a phase II reaction?

Answer 13

Glucuronidation
Sulfation
Glutathione
AAs
Acetylation

Question 14

What does NAPQI stand for?

Answer 14

N-acetyl p-benzo quinoneimine

Question 15

What drugs are considered to be inducers of the P450 monoxygenases?

Answer 15

Carbamezapline 
Rifampicin
Alcohol
Phenytoin
Greseofluvin
Phenobarbitone
Smoking

Question 16

Which common drugs are known CYP450 inhibitors?

Answer 16

erythromycin
sodium valproate
simvostatin 
omeprazole
fluconazole

Question 17

What are considered clinically significant drug interactions?
(In the context of CYP450 enzymes)

Answer 17

When the substrate of CYP450 has a narrow therapeutic index or there are significant effects at sub-therapeutic or toxic levels

Question 18

Methods of drug elimination are

Answer 18

renally (majority)
faeces (via bile)
lungs (volatile gases)
tears
sweat
breast milk

Question 19

Which drug size can be filtered through glomerular filtration at the nephron?

Answer 19

< 20kDa

Question 20

What feature of drug solubility can affect filtration at the nephron?

Answer 20

reduced drug filtration if drug is bound to albumin or other plasma protein
(e.g. warfarin is bound to albumin)

Question 21

Which types of drugs are excreted through active anion transporters at the PCT?

Answer 21

acidic drugs:
penicillin
salicyclates
cephalosporins
furosemide

Question 22

Which types of drugs are excreted through active cation transporters in the PCT?

Answer 22

basic/alkaline drugs:
amiloride
morphine
pethidine
quinine

Question 23

What kinds of drugs are excreted by passive (diffusion) movement?

Answer 23

lipid soluble drugs

e.g. corticosteroids

Question 24

How do loop diuretics function?

Answer 24

Work on the K+Cl- co-transporter
reduce reuptake of K+, Cl- and Na+
less fluid is reabsorbed (=more urine)
reduces total body fluid

Question 25

How can intra-vessel pressure be maintained at the nephron?

Answer 25

Vasoconstriction of the efferent arteriole

Question 26

How do ACEi affect intra-nephron pressures?

Answer 26

ACEi cause vasodilation of the efferent arteriole

Leads to reduction in GFR

Question 27

What receptors mediate the fight or flight response?

Answer 27

adrenergic receptors these are a type of GPCRs
adrenergic receptors are targeted by
catecholamines such as adrenaline and noradrenaline

Question 28

What are the different type of adrenergic receptor in SNS? What kind of action do they have?

Answer 28

alpha-1
smooth muscle contraction
noradrenaline > adrenaline

alpha-2
mixed effects
adrenaline > noradrenaline

beta-1
cardiac muscle contraction
adrenaline and noradrenaline

beta-2
smooth muscle relaxation (e.g. bronchodilation)
adrenaline&raquo_space; noradrenaline

Question 29

What is meant by ‘acetylator status’

Answer 29

deficiency in hepatic N-acetyltransferase

50% of the UK population have this deficiency

Question 30

Which drugs are affects by acetylator status?

Answer 30

• isoniazid
• hydralazine
• sulfasalazine