Adrenergic Neuron Blockers Flashcards
alkaloid from roots of Rauwolfia
reserpine
This drug blocks vesicle storage of amines by IRREVERSIBLY BLOCKING VMAT (vesicular membrane-associate transporter), depleting NE, DA, 5-HT
Reserpine
Primarily used for hypertension during pregnancy
methyldopa
ANB that can cause reduction in renal vascular resistance
methyldopa
False neurotransmitter (Methyldopa metabolite)
a-methylnorepinephrine
Methyldopa’s metabolite acts as an agonist on what receptor
alpha 2.
Methyldopa inhibits what enzyme?
DOPA decarboxylase
decreases dopamine –> decreased NE/E –> lower BP and cause central effects
Common A/E of methyldopa:
sedation
ANB that can cause positive Coombs Test
methyldopa
can cause immune hemolytic reaction
ANB that may cause or exacerbate ulcers
reserpine
ANB that requires NET, uptake 1
guanethidine needs to be transported across the membrane by NET, uptake 1
Sexual dysfunction, orthostatic hypotension are common side effects of
guanethidine
VMAT mechanism:
transports NE, DA, 5-HT from synapse into presynaptic vesicles
Uses NET 1 to accumulate in nerve ending, binding to vesicles and ultimately inhibiting NE release
guanethidine
ANB with Tyramine-like effect when given IV
guanethidine
CVS effect of guanethidine
Decreased BP (triple response)
MAO inhibitors interaction with Tyramine intake?
Hypertensive crisis
MAOIs prevent metabolism of tyramine –> increased tyramine levels –> release of stored catecholmines –> excess alpha and beta stimulation
ANB that interferes with catecholamine synthesis
methyltyrosine
Uses for methyltyrosine
pheochromocytoma (lowers catecholamine levels)
What drugs decrease effects of alpha 2 agonists like methyldopa
TCA inhibits NE reuptake, increase NE levels
alpha 2 agonists lower NE levels
ANB that causes depression
Reserpine
Highly associated with causing breast carcinoma
Reserpine
Quinone intermediate
6-hydroxydopamine
No clinical uses –> neurotoxic at nerve terminals causing chemical sympathetctomy
6-hydroxydopamine
Inhibits NE release at adrenergic terminals
AND
used as a Class III antiarrhythmic
Bretylium
prototype, no longer used
These drugs act by initially activating the ganglionic nACh (N) receptors, which is then
followed by receptor blockade
Depolarizing ganglionic blockers
stimulation then block (fasciculation then paralysis)
Prototype drug for depolarizing ganglionic blockers
nicotine
lbeline, coniine, TMA and DMPP are other examples used experimentally
Prototype anti-HTN drug, the first introduced
Hexamethonium (C6)
non-depolarizing (competitive) ganglionic blocker
Ganglionic blocker used to improve GIT absorption
Mecamylamine (2ndary amine)
Ganglionic blockers have antisympathetic effects at these organs
arterioles
veins
sweat glands
Ganglionic blockers have antiparasympathetic effects here
Heart Iris Ciliary muscle GIT Urinary Salivary
Ganglionic blocker used in Tourette’s
Mecamylamine (2ndary amine)
Ganglionic blocker occasionally used in hypertensive emergencies and in neurosurgery
Trimethaphan
Inhibits tyrosine hydroxylase
methyltyrosine
Guanethedine + pheochromocytoma
HTN crisis
Guanethedine + TCAs
TCAs block NET 1, interfering with Guanethidine MoA
TCA inhibits guanethidine action by blocking the reuptake
