Ch 17 Flashcards
centrally acting A2 agonists act as
direct acting adrenergic receptor blocker
Clonidine is approved for
HTN
severe pain
ADHD
centrally acting a2 agonist
Clonidine and HTN
works on the brainstem -> reduces sympathetic outflow to blood vessels and heart
Adverse effects of Clonidine
Drowsiness xerostomia rebound HTN abuse constipation impotence gynecomastia vivid dreams nightmares anxiety depression
Rebound HTN with Clonidine symptoms and why
symptoms
nervousness
tachycardia
sweating
occurs in response to clonidine withdrawal
can be avoided by withdrawing slowly over 2-4 days
if blood pressure climbs dangerously high, it should be lowered with a combo of _____ for rebound HTN
combo of A and B adrenergic blocking agents
clonidine and pregnancy
no
abuse potential of clonidine
euphoria
sedation
hallucinations
also can intensify effects of some abused drugs such as benzodiazepines, cocaine and opioids
extended release clonidine for ADHD
Kapvay
Pt education for Clonidine
take major portion of daily dose at bedtime to minimize daytime sedation
for transdermal patches - apply to hairless, intact skin on upper arm or torso and apply a new patch every 7 days
Patch contains metal - must be removed for MRI
take and record BP daily - call if hypotension develops
Do not discontinue abruptly - can cause tachycardia and other dysrhythmias. Advise to carry an adequate supply when traveling and a copy of prescription
possible CNS depression- avoid driving or hazardous activities if alertness is reduced.
Dry mouth - chew sugarless gum, sucking on hard sugar free candy, sip fluids
potential for rebound hypertension - refill promptly so dont run out. never discontinue on own
centrally acting A2 agonist indicated for HTN and ADHD, similar to Clonidine
Guanfacine
sedation and dry mouth,
rebound HTN with abrupt withdrawal
oral antihypertensive that lowers BP by acting at sites within CNS (safe in pregnancy)
Methyldopa
Methyldopa severe side effects
hemolytic anemia
hepatic necrosis
How is Methyldopa an A2 agonist
methyldopa is taken into the brainstem and converted into methylnorepinephrine - a effective A2 agonist
Do you have to worry about orthostatic hypotension with Methyldopa or Clonidine
no
Labs for Methyldopa
Combs test
Blood counts (Hgb, HCT, red cell count)
before and periodically thereafter
(CBC)
liver Function Test
A positive coombs test
if they do not develop hemolytic anemia, they can continue on Methyldopa
if they develop hemolytic anemia -> withdraw Methyldopa (coombs may remain positive for months)
a positive coombs test usually occurs (if its going to occur)
between 6-12 months
Methyldopa and hepatotoxicity
associated with hepatitis, jaundice and rarely fatal hepatic necrosis.
other adverse effects of Methyldopa
xerostomia sexual dysfunction orthostatic hypotension drowsiness reduced mental acuity nightmares depression
children and centrally acting A2 agonist
approved for age 6 and older
centrally acting A2 agonist pregnant
no for clonidine
methyldopa yes
centrally acting A2 agonist and breastfeeding
no for clonidine
older adults and centrally acting A2 agonist
BEERS says no for 65 and older
