Adrenergic Pharmacology

Question 1

What does post-autonomic ganglion neurotransmission depend on?

Answer 1

Catecholamines

Question 2

Where is noradrenaline released from

Answer 2

sympathetic nerve fibre ends, often used in the intensive care unit

Question 3

Where is adrenaline released from

Answer 3

adrenal glands (fight or flight, management of anaphylaxis

Question 4

What is dopamine

Answer 4

The precursor for adrenaline and noradrenaline
Tyrosine -> DOPA -> Dopamine -> Noradrenaline -> Adrenaline

Question 5

Alpha 1 receptor activation role

Answer 5

(NAd > Ad)
A1 activation = contracts smooth muscle= vasoconstriction, mainly in the skin and splanchnic (abdominal) beds
Noradrenaline is given IV for shock in ITU setting, or to overcome anaesthetic agents alpha blocking effects
However, adrenaline is stable and available intramuscularly, so useful in anaphylactic shock
Topical alpha activation useful in nasal decongestion (xylometazoline)

Question 6

Alpha 2 receptor activation role

Answer 6

(NAd=Ad)
Mixed effects on vascular smooth muscle
Exist in brain
E.g., clonidine = alpha-2 agonist used in ADHD to help concentration - reduces vascular tone and reduces blood pressure

Question 7

Alpha 1 blocker role and example

Answer 7

Lower blood pressure
e.g doxazosin (generally less frequently used than modern antihypertensives)
e.g phenoxybenzamine = phaeochromocytoma (catecholamine secreting tumour)
e.g. tamulosin for BPH

Question 8

Alpha 2 blocker example

Answer 8

Tetracyclic antidepressants are A2 blockers
e.g mirtazapine
but antidepressant effect from other mechanism
Mainly used in research - no clinically useful applications yet found

Question 9

Beta 1 receptors

Answer 9

Beta 1 receptor mainly in the heart, kidney and fat cells
Agonism leads to - Tachycardia, increased stroke volume, renin release (increase in vascular tone)
Lipolysis and hyperglycaemia

Question 10

Beta 1 blockers role

Answer 10

Reduce heart rate
reduce stroke volume
reduce myocardial oxygen demand and help remodelling in heart failure or post-myocardial infarction
e.g. bisoprolol, propranolol
Caution in asthma

Question 11

Beta blocker overdose treatment

Answer 11

Glucagon increases heart rate and myocardial contractility irrespective of the presence of beta-receptor blockers

Question 12

Beta 2 receptor role

Answer 12

Bronchi - bronchodilation
Bladder wall - inhibits micturition
Uterus - inhibition of labour
Skeletal muscle - increase contraction speed (induces tremor)
Pancreas - insulin and glucagon secretion

Question 13

Beta 2 agonist drugs

Answer 13

Salbutamol - useful in asthma and COPD
Side effects - tremor, hyperglycaemia (glucagon release) and tachycardia
Also used in tocolysis (delayed preterm labour)