8 Adrenergic Antagonists

What is the example medication for Alpha 1 Blockers (antagonists)?

Prazosin (-osin suffix)

Prazosin primarily used to treat what?

also treats

• Benign prostatic hyperplasia (BPH) – relaxes prostate & bladder neck

• Renal stones –  facilitates stone passage (relaxes passageway)

• Pheochromocytoma – pre-op BP control

• Raynaud's disease – peripheral vasodilation

• Reversal of α1 agonist overdose/toxicity

• Phentolamine (non-selective): antidote for IV extravasation of α1 agonists

• Nightmares associated with PTSD (off-label)

essential hypertension

What adverse effect is the main worry when initially administering Prazosin?

• also has following adverse effects

  • Reflex tachycardia (baroreceptor reflex)

  • Nasal congestion

  • Inhibition of ejaculation (erectile dysfunction)

  • Sodium & water retention (↑ blood volume)

Orthostatic hypotension (First Dose Effect)

What is an example medication of a non-selective Alpha Blocker (Antagonist)?

Phentolamine

What are the therapeutic uses for Phentolamine?

• Pheochromocytoma

• Treatment of tissue necrosis after extravasation of α1 agonist (antidote)

  • Given SQ diluted with saline for extravasation treatment

What are the adverse effects for Phentolamine?

Significant reflex tachycardia

• also same as a1 antagonists

What is the example medication for a 1st generation Beta Blocker?

Propanolol (Inderal)

What is the MOA for Propanolol (Inderal)?

Non-selective: Blocks B1 + B2

What are the uses for Propanolol (Inderal)?

HTN, angina, dysrhythmias, MI, stage fright

What are the adverse effects of Propanolol (Inderal)?

Bronchoconstriction, ↓ glucose clearance, bradycardia, fatigue

What is the example medication for a 2nd generation Beta Blocker?

Metoprolol (Lopressor/Toprol XL)

What is the MOA for Metoprolol (Lopressor/Toprol XL)?

Cardioselective: blocks B1 only

What are the uses for Metoprolol (Lopressor/Toprol XL)?

HTN, angina, dysrhythmias, MI, heart failure (HF)

What are the adverse effects of Metoprolol (Lopressor/Toprol XL)?

Bradycardia, fatigue, HF precipitation, rebound excitation if stopped abruptly, masks hypoglycemia

What is the example medication for a 3rd generation Beta Blocker?

Carvedilol (Coreg)

What is the MOA for Carvedilol (Coreg)?

Nonselective: blocks β1 + β2 + a1 (→ vasodilation)

What are the uses for Carvedilol (Coreg)?

HTN, angina, HF, MI

What are the adverse effects of Carvedilol (Coreg)?

All β1, β2, AND α1 adverse effects (orthostatic hypotension, bronchoconstriction)

Nursing Responsibilities

What should you tell a pt when they are stopping beta blockers?

never stop abruptly; taper to avoid rebound excitation

Nursing Responsibilities

You should hold Beta blockers and notify the provider during what situation?

pt HR < 60bpm & BP < 90/60

Nursing Responsibilities

What should you monitor in diabetic patients who are prescribed Beta Blockers?

Glucose (masked hypoglycemia signs: increased HR)

Nursing Responsibilities

What education(s) would a pt need when on Beta Blockers?

Do not double dose if missed

Rise slowly to prevent orthostatic hypotension

If a pt has asthma and requires a beta blocker to treat their HTN, which beta blocker is safe?

Metoprolol [Lopressor/Toprol XL]