F5 Autonomic pharmacology

Question 1

describe how an action potential block occurs

Answer 1

• blockage of voltage-gated sodium ion channels (main channel that triggers depolarisation)
• prevents excitation of both pre and postsynaptic cells

Question 2

what 2 drugs can block action potentials?

Answer 2

• lidocaine (local anaesthetic)
• lamotrigine (anti epileptic)

Question 3

describe lamotrigine effects

Answer 3

• acts in the CNS
• voltage-gated sodium ion channel blocker

Question 4

describe how lidocaine can block sodium ion channel pore

Answer 4

• blocks the pore of the channel after it has opened by docking into it
• prevents the passage of ions so no triggering of an action potential

Question 5

what does the inhibition of synthetic enzymes lead to?

Answer 5

depletion of transmitter

Question 6

what is methyl-DOPA and what happens when it is supplied?

Answer 6

• a false substrate for DOPA decarboxylase
• gets converted by DOPA decarboxylase and produces methyl-dopamine (can’t be converted into noradrenaline)

Question 7

what does the production of methyl-dopamine by DOPA decarboxylase lead to?

Answer 7

• saturation of cell by making false products that aren’t useful or making noradrenaline
• depletion of vesicles

Question 8

what can not be converted into noradrenaline?

Answer 8

methyl-dopamine

Question 9

what is the precursor for noradrenaline?

Answer 9

dopamine

Question 10

how can L-DOPA be used?

Answer 10

• therapy in Parkinson’s disease
• gets converted into dopamine in the CNS and alleviates some symptoms

Question 11

what can prevent vesicle loading?

Answer 11

• inhibition of vesicle transporter
• reserpine blocks NA uptake (and other monoamines)

Question 12

what does reserpine do?

Answer 12

blocks neurotransmitter loading

Question 13

what happens if neurotransmitter fails to load?

Answer 13

• vesicles fail to load / package
• stores are depleted by ongoing activity
• there won’t be anymore neurotransmitter released because they’re not packaged into vesicles

Question 14

what does calcium trigger in synapses?

Answer 14

• vesicle fusion and transmitter release

Question 15

what does conotoxin do?

Answer 15

• blocks calcium channels
• used in experiments for further studies on how to block calcium channels, not used therapeutically

Question 16

what does botulinum toxin (botox) do?

Answer 16

• degrades vesicle release machinery
• very potent, a small amount can shut down synaptic transmission

Question 17

what does antagonism of ionotropic receptors cause?

Answer 17

prevents depolarisation of the postsynaptic cell

Question 18

what are the several mechanisms of antagonism of ionotropic receptors?

Answer 18

• occupy NT binding site
• prevent channel opening
• block the open pore

Question 19

explain the mechanism of the antagonists of ionotropic receptors: occupy NT binding site

Answer 19

competitive antagonist and blocks ion channel

Question 20

explain the mechanism of the antagonists of ionotropic receptors: prevent channel opening

Answer 20

make a molecule that binds to an allosteric site which will cause a conformational change in the binding site

Question 21

explain the mechanism of the antagonists of ionotropic receptors: block the open pore

Answer 21

• similar to Lidocaine
• binds to the pore of the open channel which prevents any influx

Question 22

what does antagonism of metabotropic receptors cause?

Answer 22

• prevents target cells from responding to released NT

Question 23

what do antagonists that bind to metabotropic receptors do?

Answer 23

occupy binding site or allosteric site or inhibit G protein activation

Question 24

what does inhibition of transporters / degradation enzymes lead to?

Answer 24

prolonged activation of postsynaptic cell

Question 25

what does amitriptyline do?

Answer 25

- inhibits NA uptake - antidepressant that inhibits noradrenaline reuptake - leads to more NA at the synapse to bring about more signalling

Question 26

how are drugs used on the ANS? 2 methods

Answer 26

- aimed at correcting defects in the ANS itself - (more commonly) exploit the ANS to correct other problems

Question 27

give examples of defects in the ANS that drugs can be used to target

Answer 27

- primary or secondary autonomic dysfunction - diabetic neuropathy (neurons in the CNS are dying off so drugs are used to correct this issue)

Question 28

give some examples of issues that can be corrected by drugs targeting the ANS that are not ANS specific

Answer 28

- hypertension - asthma - incontinence

Question 29

give 3 examples of antagonist drugs (1 mAChR blocker, 1 beta AR blocker and 1 alpha AR blocker)

Answer 29

- Tropicamide (mAChR blocker) - Atenolol (beta AR blcoker) - Tamsulosin (alpha AR blocker)

Question 30

give 3 examples of agonist drugs (1 beta AR agonist, 1 mAChR agonist and 1 nAChR agonist)

Answer 30

- Salbutamol (beta AR agonist) - Pilocarpine (mAChR agonist) - Nicotine (nAChR agonist)

Question 31

what are the indications for beta blockers?

Answer 31

- hypertension - angina - arrhythmias

Question 32

what are the contraindications for beta blockers?

Answer 32

- asthma - COPD - bradycardia (slow heart rate) - severe peripheral arterial disease

Question 33

what is bradycardia a contraindication for beta blockers?

Answer 33

- beta blockers reduce heart rate - don't want to reduce a heart rate that is already slow

Question 34

side effects of beta blockers

Answer 34

- bronchospasm - GI disturbances - hypotension - bradycardia - visual disturbances - headache - dizziness

Question 35

general effects of beta blockers

Answer 35

- counteracts sympathetic input - reduce cardiac output - risk of pulmonary side effects

Question 36

what are antimuscarinics?

Answer 36

- antagonists for muscarinic acetylcholine receptors - eg. Hyoscine, Atropine, Oxybutynin

Question 37

what are the indications for antimuscarinics?

Answer 37

- bradycardia - GI disorders - urinary incontinence - ophthalmology - premedicants to dry bronchial and salivary secretions (especially during surgery

Question 38

contra-indications for antimuscarinics

Answer 38

- glaucoma - myasthenia graves (muscle weakness) - urinary retention

Question 39

side effects of antimuscarinics

Answer 39

- dry mouth - blurred vision - constipation - tachycardia - palpitation - arrhythmias

Question 40

general effects of antimuscarinics

Answer 40

- enhances sympathetic activities, counteracts parasympathetic input - inhibits glandular secretion - blocks smooth muscle contraction

Question 41

what can cause over dilation of pupils?

Answer 41

- too much activation of sympathetic nervous system - too much suppression of the parasympathetic system

Question 42

what are on and off target side effects?

Answer 42

- on target: hitting the right target in the wrong place - off target: hitting the wrong target

Question 43

what are pharmacodynamics?

Answer 43

what target does the drug bind to?

Question 44

what are pharmacokinetics?

Answer 44

where does the drug go in the body?