Adrenergic (2) Flashcards
Which receptor types do ergot alkaloids bind to?
Alpha-adrenoceptors
5-HT receptors
Dopamine receptors
What is the physiological effect of ergotamine and what is it used to treat?
Vasoconstrictor
Treats migraines
What is the physiological effect of ergometrine and what is it used to treat?
Uterine smooth muscle contraction
Treats post-partum haemhorrage
Bromocriptine is an agonist of which receptor type, and what is it used to treat?
D2 receptors
Treats Parkinsonism
What are the physiological effects of alpha-adrenoceptor blockade?
Decreased blood pressure - reflex tachycardia
Inability to vasoconstrict - postural hypotension and nasal congestion
Renin release - Na+ and water retention
Is prazosin an agonist or antagonist? Of which receptor type? What is its physiological effect?
Alpha1-adrenoceptor antagonist
Causes vasodilation - decreases blood pressure
What are the clinical uses of alpha-adrenoceptor antagonists?
Hypertension
Benign prostatic hyperplasia
Name a cardioselective beta1-adrenoceptor antagonist
Atenolol
Name a non-selective beta-adrenoceptor antagonist
Propranolol
What are the clinical uses of beta-adrenoceptor antagonists?
Angina Hypertension Glaucoma Anxiety Arrhythmias
What are the contraindications of beta-adrenoceptor antagonists?
Asthma
Peripheral vascular disease
What are the side effects of beta-adrenoceptor antagonists?
Bradycardia
Breathlessness
Cold extremities
What are the six stages where drugs can interfere with sympathetic transmission?
Ganglia Synthesis Storage Release Uptake Metabolism
What is hexamethonium and what does it do?
nAChR antagonist
Blocks ganglion - prevents post-ganglionic neurotransmitter release
What does disulfiram do?
Inhibits dopamine-beta-hydroxylase - prevents NA synthesis
What does reserpine do?
Binds irreversibly to VMAT - inhibits vesicular NA uptake - depletes vesicular NA storage
What is guanethidine and what does it do?
Pumped into vesicles - displaces NA
Pre-junctional alpha2-adrenoceptor agonist
Also blocks Na+ channels in neuron terminal
Blocks adrenergic neuron release
What does desmethylimipramine do?
Prevents NA reuptake
What does phenelzine do?
Inhibits MAO (MAOI)
What is the rate-limiting step in NA synthesis and which enzyme does it require?
L-tyrosine to L-dopa
Requires tyrosine hydroxylase
Which drug inhibits tyrosine hydroxylase?
Alpha-methyltyrosine
What is the final step of NA synthesis and which enzyme does it require?
Dopamine to NA
Requires dopamine-beta-hydroxylase
Name 2 examples of uptake1 inhibitors and describe their effect
Cocaine, tricyclic antidepressants
Prevent NA reuptake into pre-junctional neuron - more sympathetic effects
Tyramine binds to which type of receptors?
Post-junctional alpha-adrenoceptors
What are the physiological effects of tyramine if it is not broken down?
Vasoconstriction - increased peripheral resistance - increased risk of subarachnoid haemorrhage
