Help with NCLEX question re: beta blockers

Sarcolemma · Mar 22, 2009

Hi guys, I was wondering if anyone can help me with the beta blocker? I have been studying all day and I can't seem to get it in my head.

I'm confused with the selective and non selective antagonists!! I'm trying to answer one of my nclex practice questions but I'm super stuck. Please help!!

Which of the following drugs is the preferrred treatement with a beta blocker?
a> propranolol
b>timolol
C>Nadolol
d>Atenolol

depends on what you're treating. For example, an asthmatic with a rapid heart rate shouldn't get a nonselective blocker, but a CHF with hypertension would probably benefit from something like labetalol (nonselective)

Ok. so beta-1 adrenergic agents targets the heart (increase HR, increases cardiac contraction)
beta-2 adrenergic agents targets the lungs (vasodilate & bronchodilate)

beta blockers will inhibit those actions. I don't know why I'm stuck. I think my brain is fried:banghead:.

help anyone please

there's 2 groups of beta blockers: selective and nonselective

selective beta blockers (metoprolol, esmolol) block just the beta 1, so they slow heart rate only. don't affect the lungs.

non-selective beta blockers (labetalol, propranolol) block both beta 1 and beta 2 receptors. so you'll get the lowered heart rate from beta 1 antagonism, but blocking the beta 2 receptors will cause bronchoconstriction.

does that help?

allnurses Guide · Mar 22, 2009

Hi guys, I was wondering if anyone can help me with the beta blocker? I have been studying all day and I can't seem to get it in my head. I'm confused with the selective and non selective antagonists!! I'm trying to answer one of my nclex practice questions but I'm super stuck. Please help!!
Which of the following drugs is the preferrred treatement with a beta blocker?
a> propranolol
b>timolol
C>Nadolol
d>Atenolol

Of those answers, I would choose d, atenolol because it is the only selective B1 blocker. All the others have both B1/B2 blockade effects. The question is kinda dumb, because "preferred drug" depends on the patient's disease process. In general though, selective is good if you only want cardiac (and renal) benefits.

Re the action, just remember:

B1: heart & kidneys, cause sympathetic stimulation by epi and norepi binding (increased HR, contractility) and also cause renin release in kidneys (increases BP via vasoconstriction).

B2: lungs (bronchodilation), small action on blood vessels (vasodilation).

So:

- you wouldn't give a non-selective BB to someone asthmatic, because blocking B2 receptors can lead to bronchospasm.

- you would give either a selective or non-selective BB to someone with hypertension because slowing HR, contractility are good things to drop BP.

- carvedilol is used in heart failure patients because it also has alpha blockade effects, which can help with the dilation of blood vessels and reduction of cardiac afterload (as well as the beta blockade).

- other reasons to choose one BB over another may relate to the duration of action (ie. nadolol is long acting) or price (propanolol is cheap).

May help if you recall that BB are also used for "stage fright" or anxiety, because they block the sympathetic nervous system response to fight/flights: reduced clammy hands, drop HR etc. If you recall that stage fright gives you increased HR, pounding pulse etc, you can remember that BB do the opposite.

Additional warning:

- BB can drop blood glucose by blocking B2-induced glycogenolysis (and other mechanisms) and can simultaneously block common signs of insulin-related hypo attack such as tachycardia etc, so be careful with BB in diabetics.

tonet0908 · Mar 22, 2009

I agree with the Atenolol answer as well. Everything Sarcolemma and ghillbert says makes sense.

WeirdNurseKelly, BSN, RN · Mar 22, 2009

I agree that Atenolol is the best drug too.

My instructor gave us a super easy way to remember the beta 1 and beta 2 receptors.

You have ONE heart which contains beta ONE receptors, you have TWO lungs which contains beta TWO receptors.

Aspiring_RN · Mar 23, 2009

Yeah, I thought atenelol because when i looked it up, it said that Atenelol is selective B1 blocker. I got confused when the question asked what BB i would use for someone who has asthma. In my head, I was thinking "why would I want to use a BB for a pt w/asthma, when Beta adrenergic drugs causes bronchodilation."

But thank you thank you that makes so much sense. Also, I thought B2 causes both broncho and vasodilation??

Aspiring_RN · Mar 23, 2009

yeah i remember that one too! =) hehe tnx

allnurses Guide · Mar 23, 2009

Yeah, I thought atenelol because when i looked it up, it said that Atenelol is selective B1 blocker. I got confused when the question asked what BB i would use for someone who has asthma. In my head, I was thinking "why would I want to use a BB for a pt w/asthma, when Beta adrenergic drugs causes bronchodilation."
But thank you thank you that makes so much sense. Also, I thought B2 causes both broncho and vasodilation??

You're absolutely correct - fixed my typo.

Aspiring_RN · Mar 23, 2009

ok that's what i thought :) thank you again!