What receptors do beta blockers act on?
alpha 1 beta 1 beta 2
Review: Alpha 1 receptors cause arteries to ______. Beta 1 receptors cause heart to beat ______ & ______. Beta 2 receptors cause bronchial _______.
B1: faster & stronger
Review: An agonist ______ the receptor. An antagonist ______ the receptor.
Name the 3 CARDIOSELECTIVE (B1) beta blockers.
2) metoprolol tartrate
3) metoprolol succinate
Metoprolol tartrate & succinate: which is short-acting; which is long-acting?
tartrate: short acting
succinate: long acting
(Remember: “Succinate lasts So long”)
Name the 2 NONSELECTIVE beta blockers.
2) carvedilol (least selective)
Which receptors does propanolol block?
B1 & B2
Which receptors does carvedilol block?
A1, B1, & B2
It is the least selective!
What is one problem we see with the nonselective beta blockers?
bronchoconstriction, b/c they block B2 receptors
Name 5 indications of beta blockers?
- Angina pectoris (chest pain)
- Post MI
- HF (heart failure)
Why are beta blockers indicated for HTN?
They decrease cardiac output by decreasing HR (Remember: CO = HR x SV)
Why are beta blockers indicated after a heart attack?
can decrease mortality b/c they provide cardioprotection
What are the only 2 beta blockers indicated for heart failure?
carvadilol & metoprolol succinate
What are 3 additional indications for propranolol?
- stage fright
Can propranolol cross the BBB? What benefit can that have?
Yes! This allows it to have a prophylactic effect on migraines.
What type of adrenergic blockers are most likely to cause orthostatic hypotension?
Alpha 1 blockers (Carvedilol)
What is it called when the BP drops significantly when a person stands up?
Orthostatic or postural hypotension
What causes orthostatic hypotension?
Blood pools in the veins decreasing venous return. This, in turn, decreases cardiac output dropping BP
What are adverse effects of beta blockers?
- symptoms of low BP or HR
- fatigue, depression
- masking hypoglycemia
What should you teach a diabetic patient on a BB to look for to identify hypoglycemia?
- difficulty concentrating
- unusual fatigue
- check blood sugar often
“Cold & clammy, needs some _____; hot & dry, sugar is _____.”
What is the black box warning regarding BB’s?
Do not abruptly stop a BB unless it’s absolutely necessary. Could cause HR and BP to skyrocket, and in extreme cases could cause death.
If heart rate is below 60, should you administer a BB?
No. Hold med and contact physician.
What is reflex tachycardia?
A reduction in arterial pressure is sensed by the baroreceptors in the aortic arch and carotid sinus. The brain overcompensates by telling the heart to beat faster.
(Bad because tachycardia puts an added burden on the heart)
Why shouldn’t a person with a severe allergy (e.g., peanut) take a BB?
b/c the B1 receptor would be blocked, so adrenalin/epi. won’t work.
Why should you never abruptly stop a BB?
The BP and HR may sky rocket. (When you take the foot off the brake, the gas will be pushed down harder.) Someone with angina or CAD could have an MI and die!