What sympatholytic agents interfere with NE release or deplete NE?
RESERPINE
Bretylium
Guanadrel
Guanethidine
What are the centrally acting a2 adrenergic agonists?
CLONIDINE
METHYLDOPA
guanfacine
What is the mechanism of guanethidine?
Can it enter the CNS?
USE?
nUptake I
Displacement & release of NE
Blocks NE release
nHighly charged, does not enter CNS
essential hypertension uncontrolled by other agents
Orthostatic hypotension and other side effects limit usefulness
What is a sympatholytic drug that is a
Antiarrhythmic?
WHat is its mechanism?
What does it treat?
Bretylium
blocks NE release
nprolongs ventricular action potential and refractory period
prophylaxis & treatment of V-fib, 2nd line agent
How does reserpine work?
Depletes NE by blocking vesicular transporter
ndecreases C.O.- antihypertensive (last choice)
WHat do brain stem a2 receptors effect?
Control (inhibit) sympathetic outflow to periphery
Decrease sympathetic tone
WHat is clonidine?
a2-adrenergic receptor agonist
WHat effects does clonidine have? Think about administeration route.
IV- increase BP (peripheral a2) followed by decreased BP (central a2)
Oral - decreased BP (decreased C.O., preload)
Patch - same as oral
What is the clinical use and side effects of clonidine?
Essential hypertension (very little use now)
adjunct for narcotic withdrawal
other off-label uses
ndry mouth, sedation, impotence
nsudden withdrawal causes hypertensive crisis
How does methyldopa act?
what is it converted to?
How is it stored?
what is it the drug of choice for?
a2 agonist
methyl-NE
stored in vesicles instead of NE
hypertension in pregnant females
What are
Guanabenz and Guanfacine?
Central a2-adrenergic receptor agonists
WHat are they used to treat?
like clonidine but less used
Also used to treat tics or Tourette’s syndrome
Sometimes used for behavioral symptoms, such as impulse control disorders.
