Drugs M&R

Question 0

Where are nAChR found?

Answer 0

Post ganglionic neurones in SNS
Post ganglionic neurones in PNS
Skeletal muscle effectors

Question 1

Describe the action of nAChR antagonist

Answer 1

These drugs bind to nAChR, thereby reducing the amount of ACh that can bind

Question 2

What is trimethapan an example of? What is the clinical use of this drug?

Answer 2

nAChR antagonist

Controls hypotension in surgery

Question 3

What are tubocurarine and pancuronium examples of? What is the clinical effect of these drugs?

Answer 3

nAChR antagonist

Muscle paralysis during anaesthesia

Question 4

Describe the action of an mAChR agonist

Answer 4

These drugs bind to and stimulate mAChR

Question 5

Where are mAChR found?

Answer 5

PNS - effectors

SNS - effectors of sweat glands only (rest are adrenoceptors)

Question 6

What is pilocarpine an example of? What is the clinical use of this drug?

Answer 6

MAChR agonist
Major- Glaucoma
Minor- suppression of atrial tachycardia, increasing GI activity after abdominal surgery, stimulation of bladder emptying

Question 7

Describe the action of mAChR antagonists

Answer 7

These drugs bind to mAChR, thereby reducing the amount of ACh that can bind

Question 8

What is hyposcine an example of? What is the clinical use of this drug?

Answer 8

mAChR antagonist
Anaesthetic pre-medication - decreases bronchial and salivary secretions, prevents reflex bronchoconstriction, reduces anaesthetic induced bradycardia, sedative effect

Question 9

What is ipratropium bromide an example of? What is the clinical use of this drug?

Answer 9

mAChR antagonist

Asthma- treats bronchoconstriction caused by increased parasympathetic discharge

Question 10

What are homotropine and tropicamide examples of? What is the clinical use of these drugs?

Answer 10

mAChR antagonist
Ophthalmoscopic examination (eye conditions) - pupillary dilatation and paralysis of accommodation

Question 11

What is tolteridine an example of? What is the clinical use of this drug?

Answer 11

mAChR antagonist

Over active bladder

Question 12

Describe the action of AChEsterase inhibitors

Answer 12

These are drugs that bind to AChEsterase, preventing ACh from binding and thereby increasing the length of time ACh is available to stimulate receptors

Question 13

What are pyridostigimine, physostigimine, dyflos and edrophonium examples of? What is the clinical use of these drugs?

Answer 13

AChEsterase inhibitor

Myesthenia gravis and glaucoma

Question 14

What are tacrine and donepezil examples of? What is the clinical use of these drugs?

Answer 14

AChEsterase inhibitor

Alzheimer’s disease

Question 15

Describe the action of B1 agonists

Answer 15

These drugs bind to and stimulate B1 adrenoceptors

Increase in Heart rate and Force of contraction

Question 16

Where are B1 adrenoceptors found?

Answer 16

Heart (SAN and Myocardium)

Question 17

What is dobutamine an example of? What is the clinical use of this drug?

Answer 17

Selective B1 agonist
Positive inotropic and chronotropic effects in the heart, in treating circulatory shock (prone to causing cardiac dysrhythmias)

Question 18

Describe the action of B2 agonists

Answer 18

These drugs bind to and stimulate B2 adrenoceptors
Vasodilation in blood vessels
Bronchodilation in airways

Question 19

Where are B2 adrenoceptors found?

Answer 19

Blood vessels

Airways

Question 20

What are salbutamol and terbutaline examples of? What is the clinical use of these drugs?

Answer 20

Selective B2 agonist

Highly effective in reversing bronchoconstriction in Asthmatics

Question 21

Describe the action of a1 agonists

Answer 21

These drugs bind to and stimulate a1 adrenoceptors
Vasoconstriction in blood vessels
Dilation of pupil
Localised secretion from sweat glands

Question 22

Where are a1 adrenoceptors found?

Answer 22

Blood vessels
Pupil of eye
Sweat glands

Question 23

What are phenylephrine, oxymetazoline and adrenaline examples of? What is the clinical use of these drugs?

Answer 23

Selective a1 agonists
Nasal decongestant, may be given with a local anaesthetic injection to cause local vasoconstriction and so retard the dissipation of the anaesthetic

Question 24

Describe the action of a2 agonists

Answer 24

These drugs bind to and stimulate a2 adrenoceptors

Question 25

Where are a2 adrenoceptors found?

Answer 25

Presynaptic axons - NA reuptake

Question 26

What is clonidine an example of? What is the clinical use of this drug?

Answer 26

Selective a2 agonist Antihypersensitivity agents (Stimulation of inhibitory presynaptic receptors which decrease NA release via a centrally mediated action)

Question 27

Describe the action of a adrenoceptor antagonists

Answer 27

These drugs bind to a adrenoceptors, thereby reducing the amount of NA that can bind

Question 28

What are phentolamine and phenoxybenzamine (irreversible) examples of? What is the clinical use of these drugs?

Answer 28

a adrenoceptor antagonist Cause peripheral vasodilation in PVD (oppose sympathetically mediated vasoconstriction) Not used to treat hypertension as they can cause postural hypotension and reflex tachycardia Pheochromocytoma- block the effect of excess secreted NA by tumour

Question 29

Describe the action of selective a1 antagonists

Answer 29

These drugs bound to a1 adrenoceptors, thereby reducing the amount of NA that can bind

Question 30

What is prazosin an example of? What is the clinical use of this drug?

Answer 30

Selective a1 antagonist | Hypertension (but postural hypotension and impotence are unwanted side effects)

Question 31

Describe the action of B antagonists

Answer 31

These drugs bind to B adrenoceptors, thereby preventing NA from binding

Question 32

What are atenolol and propranolol examples of? What is the clinical use of these drugs?

Answer 32

B adrenoceptor antagonists | Hypertension, cardiac dysrhythmias, angina and MI

Question 33

What are the major unwanted side effects of B antagonist drugs?

Answer 33

Bronchoconstriction, bradycardia, cold extremities, insomnia, depression

Question 34

What are aprenolol and oxprenolol examples of? What is the clinical use of these drugs?

Answer 34

Partial B adrenoceptor agonists Believed to cause fewer side effects than B antagonists, when treating hypertension, cardiac dysrhythmias, angina and MI This is because they provide a low tonic stimulation of B adrenoceptors while still blocking receptor stimulation by NA

Question 35

How does a-methyl tyrosine work? What is its clinical effect?

Answer 35

Competitively inhibits tyrosine hydroxylase and therefore blocks de novo synthesis of NA. Its only clinical use is to inhibit NA synthesis in pheochromocytoma.

Question 36

How does a-methyl DOPA work? What is its clinical effect?

Answer 36

Taken up by adrenergic neurones and is converted to a-methyl-NA. Unlike the true neurostransmitter, it is poorly metabolised and therefore accumulates in the synaptic vesicles of noradrenergic terminals. When released by Ca2+ mediated exocytosis, it preferentially activates pre-synaptic a2 receptors. The bg subunit of the a2 receptor inhibits the VOCC, reducing Ca2+ mediated neurotransmitter release.

Question 37

How does Carbi-DOPA work? What is its clinical effect?

Answer 37

Inhibits DOPA decarboxylase in the periphery, but not in the CNS (Does not cross the BBB). It is used in combination with L-DOPA in the treatment of Parkinson’s disease.

Question 38

How do adrenergic blocking drugs work? What are their clinical effects? What are some examples?

Answer 38

Selectively concentrated in terminals by Uptake 1. They act via a variety of mechanisms, including a local anaesthetic action reducing impulse conduction & Ca2+ mediated exocytosis, partial blocking action on reputable of neurotransmitter and depletion of NA from synaptic vesicles. Rarely used therapeutically because of severe side effects (postural hypotension). Guanethidine, Bretylium

Question 39

How do indirectly acting sympathomimetic agents (IASAs)? What are their clinical effects? What are some examples?

Answer 39

Structurally related to NA. Because they are only weak agonists at adrenoceptors, they are though to exert their actions by additional/other methods. IASAs are recognised and transported into the adrenergic terminal by Uptake 1 and taken up into Synaptic Vesicles. The displaced NA can leak into the synaptic cleft by a mechanism unrelated to Ca2+ mediated exocytosis. The extent to which the NA leaks into the synaptic cleft can be greatly enchanced by inhibition of the NA-degrading enzyme MAO. Tyramine, Amphetamine, Ephedrine

Question 40

How do uptake 1 inhibitors work? What are their clinical effects? What is an example?

Answer 40

``` Comprise an important class of therapeutic agents, the tricyclic antidepressants. These agents exert their therapeutic actions centrally and their possible peripheral actions (e.g. tachycardia and cardiac dysrhythmias) are unwanted side effects, avoided by choice of drug and dose. Amitryptyline ```