Centrally active Flashcards
what are the centrally active antihypertensives
methyldopa, clonidine, guanfacine
methyldopa is considered safe for ____
pregnancy
what are the adverse effects of methyldopa
sedation, dry mouth, lactation
what is the mechanism of methyldopa
it is a prodrug to alpha-methylnorepinephrine. it is an amino acid analogue of dopamine so it is transported across the BBB by amino acid transport proteins. it then acts on alpha receptors in the medulla to put the brakes on the sympathetic nervous system, decreasing sympathetic outflow
uses of methyldopa
not a top choice; last line for HTN; typically only for treatment of HTN that is refractory to other drug classes
what is the mechanism of clonidine and guanfacine
they are lipid soluble so they readily pass the BBB and become agonists for alpha 2 receptors–> stimulation of the receptors inhibits RVLM and reduces activity of the sympathetic neurons that innervate the heart and blood vessels
what happens upon sudden withdrawal of clonidine
you are “taking your foot off the brake”–> over-activity of the sympathetic nervous system results in a hypertensive crisis
what are the other uses of clonidine
analgesic effect used to control pain associated with cancer along w/ opiates, reduction in withdrawal symptoms related to opiate abuse
what is another use of guanfacine
ADHD
how do the centrally active antihypertensives lower BP
lowering HR and contractility diminishes CO. Relaxation of the veins decreases VR and CO. Relaxation of the arterial side decreases TPR. renin release decreases. the effects of sympathetic neurons on the heart and blood vessels is reduced
