Adrenergic blockers (sympatholytics) occupy alpha or beta receptors and stop norepinephrine and epinephrine from acting. Their effects are the opposite of the receptor map for adrenergic agonists.

Alpha-1 blockers relax arteriolar and venous smooth muscle (↓BP) and smooth muscle of the prostate and bladder neck (easier urine flow). Main risk: orthostatic hypotension, worst after the first dose.

Beta blockers

• Beta-1 blockade (heart): ↓heart rate, ↓contractility, slowed AV conduction, ↓renin release → lower BP and lower myocardial oxygen demand
• Beta-2 blockade (lungs, liver, vessels): bronchoconstriction, reduced glycogen breakdown (slower recovery from hypoglycemia), peripheral vasoconstriction

Most beta-blocker names end in "-olol"; the two alpha-plus-beta blockers end differently — labetalol in "-alol" and carvedilol in "-dilol."

Beta blockers

Current points: beta blockers are not first-line for uncomplicated hypertension — the 2025 AHA/ACC guideline names thiazide-type diuretics, ACE inhibitors, ARBs, and long-acting dihydropyridine calcium channel blockers as first-line. Beta blockers are chosen when there is another reason (angina, prior MI, HFrEF, AF rate control).

Alpha blockers

Pheochromocytoma rule: alpha blockade first, then a beta blocker if tachycardia persists. A beta blocker alone leaves alpha receptors unopposed → hypertensive crisis.

Beta blockers

• Bradycardia, heart block, hypotension, dizziness
• Fatigue, exercise intolerance, cold hands and feet
• Worsening HF when started or increased too fast in decompensated clients (fluid retention during early titration)
• Bronchospasm (nonselective agents; any beta blocker at high doses)
• Masked hypoglycemia — tremor, palpitations, and tachycardia are blunted; sweating is not blocked, so it remains a warning sign. Nonselective agents also delay glucose recovery
• Erectile dysfunction, sleep disturbance and vivid dreams, depression-like symptoms (lipophilic agents such as propranolol)
• Mild rise in potassium and triglycerides
• Boxed warning (e.g., metoprolol, propranolol, atenolol, timolol tablets): do not stop abruptly — rebound tachycardia, hypertension, angina, MI, and dysrhythmias. Taper over 1–2 weeks

Alpha-1 blockers: orthostatic hypotension and syncope (first dose, dose increases, missed doses), dizziness, headache, nasal congestion, reflex tachycardia, retrograde ejaculation, floppy iris syndrome.

Beta blockers — contraindications

• Sinus bradycardia, second- or third-degree AV block, sick sinus syndrome without a pacemaker
• Cardiogenic shock and acutely decompensated HF needing inotropes
• Asthma: nonselective agents are contraindicated; beta-1-selective agents only with caution. Beta-1-selective agents are generally tolerated in COPD
• Untreated pheochromocytoma (alpha blockade first)
• Acute cocaine or methamphetamine toxicity with chest pain — avoid beta blockers alone (unopposed alpha); benzodiazepines and nitrates first

Cautions: diabetes on insulin or sulfonylureas (masked hypoglycemia), peripheral artery disease and Raynaud phenomenon, hyperthyroidism (abrupt withdrawal can trigger thyroid storm), myasthenia gravis, depression, psoriasis, kidney disease (atenolol, nadolol dose adjustment).

Pregnancy and lactation: labetalol is a preferred antihypertensive in pregnancy; atenolol should not be used in pregnancy or when planning pregnancy (2025 AHA/ACC guideline; fetal growth restriction). Beta blockers taken near delivery can cause neonatal bradycardia, hypotension, and hypoglycemia — inform the neonatal team. Metoprolol, propranolol, and labetalol are generally compatible with breastfeeding.

Alpha blockers: avoid starting in clients with orthostatic hypotension or a history of syncope; caution with PDE-5 inhibitors (additive hypotension).

Major interactions

• Verapamil and diltiazem → additive bradycardia, AV block, and HF; avoid IV verapamil with IV beta blockers
• Digoxin, amiodarone, ivabradine, clonidine → additive bradycardia
• Insulin and sulfonylureas → masked and prolonged hypoglycemia
• Epinephrine → with nonselective beta blockers, severe hypertension and reflex bradycardia; reduced response in anaphylaxis (glucagon for refractory cases)
• Clonidine withdrawal is worse on a beta blocker — stop the beta blocker first when both are discontinued
• CYP2D6 inhibitors (fluoxetine, paroxetine, bupropion) raise metoprolol, carvedilol, and propranolol levels
• NSAIDs reduce the BP-lowering effect
• Other antihypertensives, alcohol, and PDE-5 inhibitors add to alpha-blocker hypotension

Listed in priority order.

1. Before every dose
   • Apical pulse for 1 full minute and BP. Common hold parameters: heart rate < 60/min or systolic BP < 90 mmHg — follow the specific order and facility policy, and notify the provider
   • Assess for dizziness, syncope, new heart block on ECG (PR interval), and HF signs (weight gain, crackles, edema, dyspnea)
2. Breathing — assess for wheezing and dyspnea, especially with nonselective agents and in clients with asthma or COPD
3. Glucose — monitor clients with diabetes more closely; teach that sweating, hunger, and confusion may be the only hypoglycemia signs
4. IV beta blockers (esmolol, metoprolol, labetalol) — continuous ECG and frequent BP; keep atropine and pacing available; labetalol IV: keep the client supine for about 3 hours after a dose and check for orthostatic hypotension before getting up
5. Alpha-1 blockers — first dose at bedtime; check orthostatic BP; fall precautions; assist with the first time out of bed
6. Surgery — beta blockers are continued, including the morning of surgery with a sip of water; a new beta blocker is not started on the day of surgery
7. Long-term review — the 2023 AHA/ACC chronic coronary disease guideline advises reassessing long-term beta blockers (beyond 1 year after MI) when LVEF is above 50% and there is no other indication; the prescriber decides

• Never stop suddenly — rebound fast heartbeat, chest pain, or heart attack can occur; refill early; the prescriber tapers when stopping
• Check your pulse (or use a home BP monitor) as taught; report a pulse below 60/min (or the number you were given), fainting, or dizziness
• Rise slowly from lying or sitting; sit on the edge of the bed first — especially after the first dose of an alpha blocker, which is taken at bedtime
• Report weight gain of 2–3 lb (about 1 kg) in a day or 5 lb (about 2 kg) in a week, swelling, or shortness of breath
• Diabetes: check glucose more often; your heart may not race when glucose is low — watch for sweating, hunger, and confusion
• Report wheezing or breathlessness
• Fatigue and cold hands are common at first and often improve; report depression, sleep problems, or sexual side effects rather than stopping the drug
• Carvedilol: take with food. Metoprolol succinate: do not crush or chew (may be split if scored)
• Tamsulosin: take about 30 minutes after the same meal each day; tell the eye surgeon before cataract surgery
• Avoid over-the-counter decongestants and NSAIDs unless approved; limit alcohol

Beta-blocker overdose: bradycardia, heart block, hypotension, cardiogenic shock, hypoglycemia, bronchospasm, altered mental status, and seizures. Propranolol can also widen the QRS (sodium-channel effect).

Management (priority order)

1. Airway, breathing, circulation; continuous ECG; IV access; check glucose
2. Atropine for bradycardia (often only partly effective); IV fluids for hypotension
3. Glucagon IV — raises cAMP and heart rate through a non-beta pathway; causes vomiting (protect the airway); supplies are limited, so high-dose insulin is increasingly started early alongside vasopressors
4. Calcium IV, high-dose insulin with dextrose (improves heart contraction; monitor glucose and potassium closely), vasopressors (norepinephrine, epinephrine)
5. Transvenous or transcutaneous pacing; lipid emulsion or extracorporeal support in refractory cases
6. Sodium bicarbonate for QRS widening (propranolol); benzodiazepines for seizures

Alpha-blocker overdose: hypotension and syncope → supine with legs raised, IV fluids, vasopressor if needed.

Abrupt beta-blocker withdrawal behaves like a toxicity — tachycardia, hypertension, angina, MI. Restart and taper as ordered.

• Beta-1-selective ("cardioselective"): metoprolol, atenolol, bisoprolol, esmolol; nonselective: propranolol, nadolol, timolol; alpha plus beta: labetalol, carvedilol
• Hold parameters: apical HR < 60/min or SBP < 90 mmHg (or per order) — check the apical pulse for 1 full minute
• Never stop abruptly (boxed warning) — taper over 1–2 weeks
• Nonselective agents → bronchospasm — avoid in asthma
• Beta blockers mask hypoglycemia (tachycardia, tremor) — sweating remains
• HFrEF: only carvedilol, metoprolol succinate, bisoprolol; start low, go slow
• Labetalol preferred in pregnancy; atenolol not used (2025 AHA/ACC)
• Alpha-1 blockers: first-dose orthostatic hypotension — bedtime dosing, rise slowly; tamsulosin → floppy iris syndrome
• Pheochromocytoma: alpha blockade before beta blockade
• Beta-blocker overdose: atropine, fluids, glucagon, calcium, high-dose insulin, pressors, pacing