CNS drugs

Question 1

what is the difference between MAO enzymes A and B?

Answer 1

A found in brain, liver, placenta, GIT and pulmonary endothelium. breaks down 5HT3, NA and dopamine and melatonin

B - found in brain, NOT found in infants. breaks down tyramine, phenylethylramine and dopamine.

Question 2

give example of MAOI selective for MAO-A?

Answer 2

moclobemide
pirlindole

Question 3

what are the effects of benzos?

Answer 3

CNS:
- sedation, reduced REM sleep
- anxiolysis
- hypnosis
- anti epileptic
- anterograde amnesia

muscle relaxation through affects in dorsal horn

CVS and resp
reduced SVR
reduced TV (slight increase in RR)

Question 4

how do benzos work?

Answer 4

bind BDZ1 and BDZ2 receptors which then associate and modulate GABA A to increase opening and conductance of ion channel - increase chloride and hyperpolarisation

Question 5

does midazolam have any active metabolites?

Answer 5

yes - oxazepam

Question 6

what are the metabolites of diazepam?

Answer 6

nordiazepam, temazepam , oxazepam

Question 7

which of the benzos has the longest eliimination half life?

Answer 7

diazepam - 36 hours

Question 8

what type of molecule is flumazenil?

Answer 8

imadazobenzodiazepine

Question 9

what is the elimination half life of flumazenil?

Answer 9

50 mins
significance of this is that may need to repeat dose or give as IV infusion

Question 10

when is flumazenil contraindicated?

Answer 10

long QTc/ QRS prolongation
dont give in mixed overdose e.g. TCA - may precipitate seizures

Question 11

which sympathetic ganglia are not adjacent to spinal cord (exceptions)?

Answer 11

coeliac and hypogastric

Question 12

which sympathetic fibres leave spinal cord?

Answer 12

preganglionic - travel in white communicates (myelinated)
then after ganglion = grey communicates

Question 13

what ANS branch does stellate ganglia contain?

Answer 13

sympathetic

Question 14

what fibres of the sympathetic nervous system does the sphlanchnic nerve contain?

Answer 14

preganglionic

Question 15

how many divisions of ANS?

Answer 15

sympathetic
parasympathetic
(enteric NS - thought to be the 3rd branch)

Question 16

what is the NT carried by each synapse in autonomic NS?

Answer 16

between pre and post ganglionic - ACh and nACh - in both symp and parasym

sympathetic post ganglionic - NA and adrenoceptors
parasympathetic post ganglionic -ACH and mACHR

exception - sympathetic sweat glands - ACh

Question 17

where is the alpha 2 receptor predominantly located?

Answer 17

pre-synaptic

Question 18

what is the main source of a2 receptors?

Answer 18

circulating catecholamines

Question 19

what does NA do to B2 and A1 receptors on smooth muscle?

Answer 19

a1 - vasoconstriction to all smooth muscle except that of GIT
B2 - vasodilation of skeletal, bronchial and uterine smooth muscle

Question 20

what enzyme is deficient in phenylketonuria?

Answer 20

Phenylalanine hydroxylase

Question 21

which receptor are adrenaline and NA mosly different?

Answer 21

Adrenaline and noradrenaline differ mainly in their effects at β2 adrenoceptors, to which noradrenaline has a much lower affinity.

Question 22

what is the half life of adrenaline?

Answer 22

1 to 3 mins

Question 23

what is the effect of ANS on the bladder?

Answer 23

sympathetic - relaxes
parasympathetic - contracts

Question 24

what is the effect of ANS on the erection and ejaculation?

Answer 24

sympathetic - ejaculation
parasymp - erection

point and shoot

Question 25

what receptors are present in ganglion of parasymp fibres?

Answer 25

mostly nicotinic but can also get muscarinic - exicitatory

Question 26

what is a NANC NT?

Answer 26

non adrenergic non cholinergic neurotransmitter.

Question 27

what does anti-cholinergics do to eye pressure?

Answer 27

dilate pupil, reduce drainage, increase eye pressures.

Question 28

how does ipratropium work?

Answer 28

muscarinic antagonist bronchodilation Gq

Question 29

what is clonidine?

Answer 29

a2 agonist this reduces NA release - hypotension also analgesic

Question 30

where does doxazocin act?

Answer 30

a1 blocker reduces SVR

Question 31

what do CaCB do to CVS system?

Answer 31

reduce contractility and CO reduce HR - reduce conduction through AVN reduce SVR

Question 32

how do phosphodiesterase inhibitors reduce SVR?

Answer 32

cAMP --> PKA --> phosphorylates MLCK --> inhibits muscle contraction. phosphodiesterase breaks down cAMP hence inhibiton will inhibit muscle relaxation

Question 33

give examples of 2 PDE (phosphodiesterase) inhibitors that act on CVS

Answer 33

milrinone Levosimendan (ca sensitiser too)

Question 34

what is the effect of PGE inhibitors on cardiac function?

Answer 34

improved ionotropy but not immediate they enhance effects of other ionotropes e.g. adrenaline

Question 35

what is ranolazine?

Answer 35

inhibitor of late inward Na current used in angina

Question 36

can spinal be done with anti-platelet therapy?

Answer 36

monotherapy with aspirin - yes no contraindication ticagrelor - stop 5 days before

Question 37

how long is dual anti-platelet therapy after PCI?

Answer 37

6 to 12 months then aspirin alone

Question 38

which angina meds should/ shouldnt be continued during surgery?

Answer 38

statins, aspirin , b blockers , anti htn (except ACE) - continue ramipril - stop ticagrelor / clop - stop

Question 39

which ion channel do CaCB effect?

Answer 39

L type

Question 40

which vessels do nitrates dilate?

Answer 40

veins predominately

Question 41

what do CaCB do to neuromuscular block?

Answer 41

prolong

Question 42

which commonly used drug can ranolazine interact with ?

Answer 42

ondansetron - both cause long QT

Question 43

what is the mechanism of action of phentolamine?

Answer 43

alpha antagonist

Question 44

which vessels do CaCB mostly affect?

Answer 44

arterial vasodilation

Question 45

what does phenytoin do to cyp450?

Answer 45

inducer decreases levels - carbemazepine, COCP, warfarin, clopidogrel, steroids, PPI

Question 46

which AED is a P-glycoprotein (P-gp) inhibitors? what does this mean?

Answer 46

phenytoin normally this pump eliminates drugs. hence inhibition increases conc of drugs / absorption. e.g pf dabigatran

Question 47

which anti-epileptics are least likely to be associated with anti-epileptic hypersensitivity syndrome?

Answer 47

levetiracetam gabapentin pregabalin valproate / topimarate

Question 48

what is anti-epileptic hypersensitivity syndrome?

Answer 48

rare, potentially fatal This syndrome typically includes symptoms such as fever, rash, and systemic involvement (e.g., hepatitis, nephritis, and hematologic abnormalities). AEDs most commonly associated with AHS include carbamazepine, phenytoin, phenobarbital, and lamotrigine.

Question 49

when is ICP monitoring in epilepsy advised?

Answer 49

In the 4th stage (aka Refractory Status, 30-90 mins)

Question 50

what is the mechanism of action of ... topiramate, vigabatrin, phenytoin, tiagabine and pregabalin?

Answer 50

topiramate - glutamate blocker vigabatrin - Gaba transaminase inhibitor phenytoin - Na channel blocker tiagabine - GABA reuptake inhibitor pregabalin - Inhibition of alpha 2-delta (α2–δ) subunit of voltage-gated calcium channels (VGCC)

Question 51

which drugs inhibit MAO A and B?

Answer 51

MAO-I A= moclobemide - reversible MAO-I B = selegeline and rasagiline - irreversible Isocarboxazid is a non-selective MAOI that binds irreversibly to MOA-A and MOA-B.

Question 52

which antimicrobial agent has MAOI activity?

Answer 52

Linezolid inhibits the action of MAO-A and can interact with MAOI to cause serotonin syndrome.

Question 53

which antipsychotic causes agranulocytosis?

Answer 53

clozapine

Question 54

what type of anti-psychotics are chlorpromazine and flupentixol?

Answer 54

Chlorpromazine is a typical antipsychotic of the phenothiazine class. Flupentixol is a typical antipsychotic of the thioxanthene class.