Question | Answer |
Drugs in this class include | clonidine [Catapress], guanabenz [Wytensin]
guanfacine [Tenex, Intuniv], methyldopa |
central alpha 2 agonists reduce sympathetic tone and increase parasympathetic tone which results in | lower BP, bradycardia, peripheral resistance |
crosses the blood brain barrier so should be used cautiously in depression, older adults, cerbrovascular disease | clonidine, methyldopa |
nightmares and insomnia have been associated with | clonidine |
have been associated with life-threatening rebound HTN mediated by increased SNS activity | so should be tapered gradually. This is exacerbated if pt is also taking beta-adrenergic blockers |
has been associated with a positive Coombs' test | methyldopa |
beta blockers and centrally acting alpha2 agonists should not be given together but if they are and one needs to be withdrawn | the beta blocker should be tapered first to prevent excessive opposed stimulaton of alpha 2 receptors that can result in a hypertensive crisis in as little as 12 hours |
because they lower BP by reducing sympathetic function, they can produce compensatory effect on BP resulting in | retention of sodium and expansion of blood volume through mechanisms that are not dependent on adrenergic nerves |
for treatment of HTN | usually 2nd line, except for methyldopa which is first line in pregnancy |
methylodopa and clonidine can be used with a diuretic to address | sodium and water rention |
combination tablet | chlorthalidone[Clorpres], clonidine with thiazide |
unlabeled uses of clonidine | withdrawal symptoms, ADHD |
monitoring during tx with methyldopa | Coombs' test before and at 6-12 months after initiation of therapy |
methyldopa adverse reactions | jaundice (hepatotoxicity), weakness [amemia], urine left standing may darken or turn red/black [not hematuria] |