Adrenergic Blockers Flashcards
When are beta blockers used?
Angina Hypertension Cardaic arrhythmias Pheochromocytoma Prevent migraine Prevent heart attacks Glaucoma
When are alpha blockers used?
Hypertension
Prostatic hypertrophy
Propranolol
Mainly blocks B1 in heart
Also blocks renin release
–JG cells have B1
Large individual variation in effect
Non-selective, also blocks B2
Timolol
Non-selective (blocks B1 and B2)
DOES NOT BLOCK Na channels (like propranolol does) -
Pindolol
Partial agonist
Less decrease in HR and BP
Useful in angina and HTN
Atenolol, metoprolol
–generally, use
Selective for B1
Less effect on lungs (can be used better in people with lung problems)
Metoprolol
–especially good asthma and in preventing CV problems e.g. in HTN
Atenolol vs Metoprolol - excretion/metabolism
Metroprolol is excreted via the urine
–good option for those with liver problems
Atenolol is metabolized by the liver (2C9)
–good option for those with kidney problems
Which are the most popular of all cardiovascular drugs?
Beta blockers
Why are beta blockers useful for angina?
They decrease HR and force, thus decreasing work
Why are beta blockers useful for HTN?
They initially decrease BP due to decrease in CO
No postural hypotension
Why are beta blockers useful for migraines?
Useful for prophylaxis
B-blockers decrease pulse pressure (which will decrease CO) – this seems to relieve some of the throbbing pain
Why are beta blockers useful for “hyper dynamic circulatory state”?
In emotional situations, there is excessive increase in HR
Can use prior to dental procedures, performances, etc. to prevent this excessive increase in HR
Why are beta blockers useful for glaucoma?
Inhibit formation of aqueous humor
can use either B1 or B2 blockers for the eye, but mostly B2 in eye
What are the drugs of choice for glaucoma?
Prostaglandin analogs
They increase the outflow through accessory uveoscleral pathway
What are disease states in which you should take precautions for using Beta blockers?
Asthma CNS "depression" Poor circulation Diabetes Rebound tachycardia
Beta blockers and CNS depression
Beta blockers may cause CNS depression, especially in those with high lipid solubility (e.g. pindolol and propranolol)
Don’t use in patients with a history of depression
Beta blockers ad circulation
Decreased CO leads to tiredness, numbness, tingling, muscle ache
Don’t use in pregnancy
Decreased exercise tolerance
Beta blockers and diabetes
Block B2 to inhibit mobilization of liver glycogen
Increases the effect of insulin
Beta blockers and Rebound tachycardia
On cessation of beta blocker therapy, rebound tachycardia can occur
–to avoid this, taper over a period of weeks
Alpha blockers MOA
competitive alpha-1 block
some also block alpha 2
How are alpha blockers useful in prostatic hypertrophy?
Example of drug used?
Used to improve urine flow
Tamulosin (flomax)
- specific for alpha 1A receptors
- less effect on blood vessels (1B)
How are alpha blockers useful in hypertension?
Examples
Dilate arteries and veins
Prasosin - t1/2 = 3 hrs
Terazosin - t1/2 = 12 hrs
Phentolamine
- -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
Urinary incontinence
What were the first known adrenergic blockers?
Ergot alkaloids
Found on rye and other grains
- -cause gangrene dur to toxic effect on blood vessels – this would happen when ate bread, etc. that was contaminated
- -also cause angina, hallucinations, abortions
Ergot alkaloids
alpha block is not part of clinical action, not even side effects
Have partion agonist activty on apha1 and 5HT1D receptors
Main effect = prolonged contraction of smooth muscle
- –act mostly on capacitance blood vessels
- –uterine smooth muscle also contracted
When is ergot used?
In migraines - to relieve painful throbbing
In post partum bleeding
Tx of migraines
-ergot - when? how?
What else can be used? with what types of migraines?
Ergot should be taken at start of headache
–even more effective when taken with caffeine
Mild migraine - aspirin
Moderate migraine - ergot
Severe migraine - beta blocker
Explain with ergot alkaloids are useful with post partum bleeding
Must bleeding occurs after the placenta tears away from the uterine wall
Ergot alkaloids contract uterus and stop bleeding
