Pharmacodynamics

Question 1

why is thiopentone stored at a pH of 11

Answer 1

to promote its ionised form to make it lipid soluble. otherwise it would precipitate out of solution

it is an acid with pKa 7.6

Question 2

what type of molecule (acid or base) is thiopentone, propofol and etomidate?

Answer 2

thio and propofol = weak acids

etomidate = weak base

Question 3

Is fentanyl an acid or base?

Answer 3

weak base

Question 4

what is the pKa of fentanyl and morphine, what does this mean?

Answer 4

both weak bases
fentanyl = 8.4
morphine = 7.9

therefore bases ionise below pH so at pH 7.4 more fentanyl will be ionised

Question 5

what amine group does morphine have?

Answer 5

tertiary amine

Question 6

what is the pka of the carbonate/bicarb buffer system?

Answer 6

6.4

Question 7

what type of drug is meperidine ?

Answer 7

opioid, weak base
Aka pethidine

Question 8

are NSAIDs acids or bases?

Answer 8

all weak acids

Question 9

what is the pka of paracetamol ? is it an acid or base?

Answer 9

9.4
weak acid

Question 10

what is the pka of remifentanil?

Answer 10

7.1

Question 11

which is the only volatile agent NOT to exist as a stereoisomer?

Answer 11

sevoflurane

Question 12

for levobupivacaine, ropivacaine and etomidate which isomer R or S is the clinically useful one?

Answer 12

bupivacaine and ropivacaine - S

Etomidate - R

Question 13

how does sugamadex work pharmacodynamically?

Answer 13

Chelating agent - encapsulates roc

Question 14

which drugs work by neutralisation

Answer 14

antacids
protamine

Question 15

What is meant by an ionotrophic receptor

Answer 15

ligand gated
ion channel

NOT the same as VG ion channel

Question 16

what 2 factors does drug potency depend on?

Answer 16

affinity and efficacy

Question 17

which value represents drug affinity and potency?

Answer 17

kd = affinity
EC50 = potency

the lower for each , the more potent/higher affinity.

Question 18

what is efficacy?

Answer 18

Efficacy is an inherent property of an agonist and reflects its ability to activate the receptor and produce a maximal biological response

Question 19

which value from the drug response curve defines efficacy

Answer 19

Emax

Question 20

define intrinsic activity

Answer 20

Intrinsic activity (IA) is the drug’s maximal efficacy as a fraction of the maximal efficacy produced by a full agonist.

Question 21

what type of intracellular receptors are oestrogen and thyroxine

Answer 21

oestrogen - type 1 - cytoplasmic
thyroxine - type 2 - nuclear

Question 22

how do intracellular receptors work?

Answer 22

intrinsic transcriptional activity, bind via zinc fingers

Question 23

what activates thyroid receptors?

Answer 23

can be active with or without ligand.
ligand = T3/T4

when active it binds to thyroid response element (not transcription activating domain)

Question 24

how are anticholinesterases divided?

Answer 24

Anticholinesterases are divided into short-, medium- and long-acting.

Question 25

what test is diagnostic for myasthenia gravis?

Answer 25

Tensilon test

Question 26

how is neostigmine hydrolysed?

Answer 26

same way as ACh just takes much longer

Question 27

how long do long acting anticholinergics last

Answer 27

weeks due to covalent bonds

Question 28

what is SLUDGE syndrome of cholinergic overdose characterised by?

Answer 28

salivation lacrimation urination defacation GI upset emesis

Question 29

where is carbonic anhydrase found?

Answer 29

renal tubules pancreatic parietal cells RBC ciliary epithelium of eye

Question 30

where are COX1 and 2 found

Answer 30

COX 1 all cells COX 2 - inflammatory cells

Question 31

how are mono-oxidase enzymes classified?

Answer 31

They are classified as MAO-A, RIMA or MAO-B

Question 32

where are mono oxidase enzymes found?

Answer 32

attached to mitochondria.

Question 33

which family are mono-oxidase enzymes from?

Answer 33

flavoprotein

Question 34

which MOA is found from birth?

Answer 34

MOA-A

Question 35

how do MAO work?

Answer 35

remove amine

Question 36

where are MAO found?

Answer 36

brain, liver, lung and placenta

Question 37

what does MAO-A breakdown?

Answer 37

MAO-A breaks down MANS (melatonin, adrenaline, noradrenaline and serotonin

Question 38

which drugs should MAO be avoided with?

Answer 38

never in combination with SSRI/SNRIs - increased levels in brain of NT --> hypertensive crisis

Question 39

which other conditions can MAO be used in?

Answer 39

depression prophylaxis migraines parkinsons

Question 40

which drug causes red man syndrome?

Answer 40

vancomycin

Question 41

what law do michelias menton kinetics obey?

Answer 41

law of mass action

Question 42

which part of the liver contains high levels of CYP450

Answer 42

Centrilobular hepatocytes (zone 3) contain high concentration of CYP 450 enzymes.

Question 43

what is the main mechanism of CYP450 enzyme induction

Answer 43

increase in gene expression - takes some time to develop

Question 44

how does dexamethasone affect CYP450

Answer 44

inducer

Question 45

how doe rifampicin, paroxetine and erythromycin effect... diltiazam, warfarin, betablockers

Answer 45

Rifampicin induces CYP2C9 with a risk of inadequate anticoagulation by warfarin. Paroxetine inhibits CYP2D6, reducing the metabolism of beta-blockers. Erythromycin inhibits CYP3A4, reducing the metabolism of diltiazem.

Question 46

what type of drug reaction is sux apnoea?

Answer 46

Type B - Bizzare

Question 47

what type of drug reaction is hypoglycaemia with aspirin?

Answer 47

type A

Question 48

what are the different methods for defining drug reaction?

Answer 48

Type A and B - understandble / bizzare - i.e. reasoning coombs - immunologicals DOTS - timing, dose and susceptibility

Question 49

what are pseudoallergic reactions?

Answer 49

present like allergy due to histamine release not immune mediated

Question 50

what is innate tolerance?

Answer 50

Innate tolerance describes a lack of sensitivity to a drug the first time it is administered

Question 51

how can tolerance be classified

Answer 51

Acquired tolerance can be subdivided into three main categories: pharmacokinetic, pharmacodynamic and behavioural tolerance

Question 52

which drugs show tachyphylaxis?

Answer 52

ephedrine hydralazine

Question 53

define summation, synergism and potentiation...

Answer 53

summation - effects are additive synergism - combined effect is more that added affect of each alone potentiation - one increases effect of another but doesnt have an effect itself

Question 54

which herbal meds interact with NSAIDs?

Answer 54

garlic, ginger, ginseng, gingco, st johns