4. Autonomic Pharmacology Flashcards
What are adrenergic agonists also known as?
Sympathomimetics
What receptors does adrenaline work on?
Both a and B adrenoceptors
What are the actions of adrenaline?
Vasoconstriction and cardiac stimulant
Increase systolic BP through B1
Dilate vessels in skeletal muscle through B2
What receptors does noradrenaline work on?
a1 and a2, some action at B1
What are the actions of noradrenaline?
Increase peripheral resistance, which increases both systolic and diastolic BP
Name a selective a1 agonist?
Phenylephrine
What are the uses of phenylephrine?
Vasoconstriction and increased BP
Vasopressors, nasal decongestant, pupil dilatation
Name a B-adrenoceptor agonist?
Salbutamol
What are the actions of salbutamol?
Vaso and broncho dilatation
Why is salbutamol not used as an anti-hypertensive?
Reduced blood pressure causes reflex tachycardia
What are adrenoceptor antagonists also known as?
Sympatholytics
Name an a-receptor antagonist?
Phenoxybanzamide
How does phenoxybanzamide work?
Binds irreversibly to receptor
Inhibits recycling of NA
Causes vasodilation at a1 so lowers BP
Name a non-selective a-receptor antagonist
Phentolamine
Why are non-selective a-receptor antagonists no longer used?
They induce tachycardia, dysrhythmias and increase GI activity
What are selective a1 antagonists used for?
Treat hypertension
What are the side effects of a1 antagonists?
Postural hypotension
Impotence
Name 2 b-receptor antagonists
Propanolol
Atenolol
What are b-receptor antagonists used for?
Arrhythmias
Angina
MI and post-MI
What side effects are associated with atenolol?
Bronchoconstriction
Bradycardia
Cardiac Failure
What are the types of nicotinic receptor?
Nm at neuromuscular junction
Nn at regions with neurotransmitters
Which muscarinic receptors increase and decrease cell excitability?
M1, 3, 5 increase
M2, 4 decrease
What enzyme breaks down ACh?
ACh esterase
Hydrolysed rapidly, choline is recycled and acetyl CoA from glycolysis used
Describe the structure of nicotinic receptors
Ligand gated ion channels
Pentameric
What does binding of ACh to a nicotinic receptor cause?
Influx of Na+ and efflux of K+
Release of intracellular Ca++
What pathway is utilised by M1, 3, 5?
Inositol triphosphate
What pathway is utilised by M2, 4?
Inhibit adenylate cyclase
Where are M1 receptors found?
Neural
Where are M2 receptors found?
Cardiac
Where are M3 receptors found?
Glands
Name an M3 agonist
Pilocarpine
What is the function of pilocarpine
Increase exocrine gland secretion
Used in glaucoma to help drain excess aqueous humor
What effect does nicotine have?
Nicotinic agonist at low doses
Causes vasoconstriction which increases BP
How do anti-AChE drugs work?
Prevent the breakdown of ACh
What drug is used in the diagnosis of myasthenia gravis?
Edrophonium
Causes eyelid weakness to be temporarily relieved
Name an anti-AChE drug that is used as a war gas?
Sarin
Causes SLUDGE syndrome
What is used as an antidote to sarin?
Atropine
What are the effects of anti-AChE drugs?
Parasympathetic effects
Increase muscle twitch
What are cholinergic receptor antagonists used for?
Control bradycardia Dilate pupil Treat asthma Control saliva Slow GIT Anti-emesis
Name a drug which is a competitive antagonist at muscarinic receptors
Atropine
Name a selective M3 antagonist used in COPD and asthma
Ipatropium
Name an M3 antagonist used to treat urinary incontinence
Darifenacin
Name an M1 antagonist used to treat peptic ulcers
Pirenzepine
What are ganglionic blocking agents?
Block ACh at nicotinic receptors
Have some use in hypertension
What can neuromusclar blocking agents be divided into?
Depolarising and non-depolarising
What are neuromuscular blocking agents used for?
Relax muscles in conjunction with anaesthesia
How does botulin toxin work?
Blocks ACh release
Name a selective a2 agonist
Clonidine
