Adrenergic Blockers Flashcards
phentolamine receptors
a1 and a2
phentolamine effects
decreased BP tachycardia, arrhythmia and MI; Hypotension Gastric stimulation due to serotonin block and muscarinic and histamine stimulation peptil ulcer and ab pain
Use of phentolamine
HTN crisis (pheochromocytoma)
patients on MAOI that ingest tyramine
abrupt withdrawal from clonidine
prevent necrosis - when vasoconstrictor like NE is administered
Pheochromocytoma tx
Phenoxybenzamine (1st)
Phentolamine
-zosin`
alpha 1 selective blockers
Prazosin dosage
duration: 7-10 hours 2x/daily
reduces reflex tachycardia
1st dose phenomenon!
(terazosin, doxazosin: better kinetics- 1/day dosing)
Prazosin use
HTN
BPH!
GREAT FOR MEN W/ BOTH
male w/ HTN and BPH
Prazosin
SE of prazosin
first dose phenomenon ortho hypotension (worse w/ viagra and nitrates!) Dizziness nasal stuffiness inhibition of ejaculation and ED
Drugs similar to prazosin
terazosin, doxasoin;
also decrease size of prostate; 1/day dosing
Treatment for BPH that has little effect on BP
Tamsulosin & Alfuzosin (not as selective)
Tamsulosin
selective for a1a and a1d (not a1b- in blood vessels); a1a in prostate; relaxes prostates makes urination easier; metabolized by P450
SE of tamsulosin
ejaculation and hypotension
SE of alfuzosin
dizziness
Best DOC for BPH w/ hypotension problems
tamsulosin (or alfuzosin)
Yohimbine
dangerous in men with HTN!!!
alpha2 antagonist- increases NE and sympathetic output
inc. HR and BP
Contraindications of beta blockers
Epinephrine
Pheochromocytoma (unless alpha-blocker is also used)
asthma (bronchoconstriction- use CCB instead)
Type 1 diabetes (no glucagon response- can’t recover from hypoglycemia or see sx)
used for glaucoma
timolol (betaxolol in asthmatics)
SE of beta-blocker
beta3 block inhibits liplysis: less free fatty acids available- chronic use increases VLDL and decreases HDL (probably partial agonists or b1 selective antagonists)
local anesthetic activity
labetalol, acebutolol, metoprolol, pindolol, propranolol (DON”T USE IN EYE)
Non-selective beta-antagonists
Propranolol
Timolol
Nadolol
Sotalol
Propranolol
slows heart, decrease contraction, decrease AV node
decrease renin release, decrease lipolysis and glycogenolysis
Negative of propranolol
may mask hyperthyroidism and hypoglycemia (makes recovery more difficult)
long term: increase VLDL, dec. HDL
Drugs that inhibit propranolol metabolism
cimetidine, chlorpromazine