Adrenergic blockers Flashcards
first beta-blocker
propranolol
- mainly blocks beta-1 in heart
- also blocks renin release:juxtaglomerular cells have beta-1
- large individual variation in effect
- NON-selective, also blocks beta-2
timolol
non-selective
-no blockage of Na channels
Pindolol
partial agonist
- less HR and BP
- angina, hypertension with bradycardia
Beta-1 selective
atenolol
metoprolol
-less effects on lungs
metoprolol
good for asthma and in preventing cardiovascular problems (in hypertension)
- excreted in urine, T1/2 of 5 hours
- extended release preparation used
atenolol
metabolized in liver (2C9),
half-life: 6 hours
most popular drug of all cardiovascular drugs
beta-blockers, used for
- angina
- hypertension
- cardiac arrhythmias: especially with strong sympathetic component
beta blocker use with angina
beta blockers decrease HR and force-> decrease work
beta blocker use with hypertension
initially decrease BP and decrease CO
-no postural hypertension
beta blockers _______ during surgery
pheochromocytoma
prophylaxis of migraine
- affects about 15% of population-> women twice as much as men
- beta-blockers: decrease pulse pressure
prevent recurrence of
heart attacks
- decrease incidence of death
- especially good after MI
beta-1 blockers in
hyperdynamic circulatory state
- excessive increase HR in emotional situations
- used prior to dental procedures, football games, musical performances, etc
glaucoma
beta blockers well tolerated
-inhibits formations of aqueous humor
Mostly Beta-2 receptors in eye
drugs of choice in glaucoma
PG analogs, increase outflow through accessory uveoscleral pathway
precautions in use of beta blockers
- Asthma (not so bad with beta-1 specific drugs), beta-2 bad to block
- CNS depression
- Poor circulation
- Diabetes
- Rebound tachycardia
precautions in use of beta blockers: CNS depression
may be caused by beta-blockers especially those with high lipid solubility ( pindolol, propranolol)
-dont use in patients with history of depression
precautions in use of beta blockers: poor circulation
decreases CO leads to tiredness, numbness, tingling, muscle ache
- dont use in pregnancy
- decrease exercise tolerance
precautions in use of beta blockers: diabetes
block beta-2 to inhibit mobilization of liver glycogen
-increases effect of insulin
precautions in use of beta blockers: rebound tachycardia
cessation of therapy
-taper dose over period of weeks
Alpha blockers
competitive alpha-1 blockers
-some also block alpha-2
clinical use of alpha blockers
prostatic hypertrophy
improve urine flow
tamusolin (Flomax)
specific for alpha-1 receptors
-less effect on blood vessels (1B)
alpha blockers for increase in BP
dilates arteries and veins
- prasosin T1/2 3 hours
- terazosin T1/2 12 hours
phentolamine (older drug), nonspecific
-alpha1/alpha2= 4/1
can cause tachycardia, used to block necrosis by injected sympathomimetics
precautions and side effects of alpha-1 blockers
- postural hypotension
- nasal stuffiness
- impaired sex function-> failure of ejaculation
Ergot alkaloids 1st known adrenergic blockers
-powerful alkaloids which can cause gangrene due to toxic effect on blood vessels, can also cause angina, hallucinations, abortions
Ergot alkaloids
alpha-blockers: not part of clinical actions, not even side effects
-have partial agonist activity on alpha-1 and 5HT1D receptors
-Main effect: prolonged contraction smooth muscle
acts mainly on capacitance blood vessels, uterine smooth muscle also contracted
what is Ergot used in?
Migraine
- relieves painful throbbing with each heart beat
- taken at start of headache
- erotamine even more effective when taken with caffeine
mild migraine
aspirin
moderate migraine
ergot
severe migraine
beta blockers
what else of ergot alkaloids used for
post partum bleeding
- much bleeding occurs when placenta tears away from uterine wall
- ergot alkaloids contract uterus and stop bleeding
- agonists or partial agonists on 5HT/alpha-1 receptors
- ergonovine
