Beta-Blockers
High-yield Verified · Oct 2026Block catecholamine access to β1 receptors (Gs → cAMP) in the heart and kidney — slowing the SA node and AV conduction, weakening contraction and cutting renin — and, in non-selective agents, β2 receptors in the bronchi and vessels.
Nursing view → administration, monitoring and patient teaching
Compare: Antiarrhythmics by Vaughan-Williams class →
Compare: Antihypertensives compared — mechanism and drug choice →
Drugs
Mechanism
Competitively block β1 (cardioselective agents) and, non-selectively, β2 adrenergic receptors, reducing sympathetic stimulation of the heart — lowering heart rate, contractility, and cardiac output, and decreasing renin release. Labetalol and carvedilol also block α1 receptors, and nebivolol causes nitric-oxide–mediated vasodilation; pindolol and acebutolol have partial-agonist (intrinsic sympathomimetic) activity.
Three adrenergic receptors, two second-messenger systems
The β1 receptor is a G-protein-coupled receptor that signals through Gs: adenylyl cyclase converts ATP to cAMP, and cAMP-dependent protein kinase A (PKA) phosphorylates calcium channels, so more calcium enters the cell. In the heart this increases SA-nodal, AV-nodal and ventricular firing — faster rate and stronger contraction. In the kidney, β1 activation of juxtaglomerular cells releases renin.
The β2 receptor also raises cAMP and activates PKA, but in smooth muscle the result is relaxation — of the bronchi and of blood vessels — along with metabolic effects such as glycogenolysis. The α1 receptor couples to Gq instead: phospholipase C generates IP3 and DAG, intracellular calcium rises, and vascular smooth muscle contracts, raising vascular resistance and blood pressure.
β-blockade is surmountable. Propranolol is a competitive inhibitor of β-agonists, so enough dobutamine or isoproterenol can reverse its effects — and propranolol may reduce the sensitivity of dobutamine stress echocardiography.
What blockade does, tissue by tissue
At the SA node, β1 blockade lengthens the sinus cycle and the sinus-node recovery time (negative chronotropy). At the AV node it slows conduction and lengthens the refractory period, which shows up as a longer PR interval; on maintenance therapy this rarely goes beyond first-degree AV block. In the ventricles contractility falls (negative inotropy).
Blood pressure falls by routes the labels list without settling on one: lower cardiac output from antagonism at cardiac receptors, less sympathetic outflow from vasomotor centers in the brain, and suppressed renin. With propranolol, total peripheral resistance may rise at first, then return to or below baseline with chronic use. Myocardial oxygen demand falls because heart rate, systolic pressure and the velocity and extent of contraction all fall.
Blocking β2 removes the cAMP signal that relaxes smooth muscle: in patients prone to bronchospasm the bronchi constrict passively because endogenous adrenergic bronchodilator tone is lost, and vessels constrict mildly. Metabolically, β-blockade removes catecholamine-driven glycogenolysis and gluconeogenesis, and it also reduces insulin release in response to hyperglycemia.
Selectivity is relative; ISA is partial agonism
β1 selectivity (atenolol, metoprolol, esmolol, acebutolol, nebivolol) is a matter of degree. Metoprolol’s label shows it two ways: metoprolol cannot reverse epinephrine’s β2-mediated vasodilation, and in asthma it lowers FEV1 significantly less than propranolol at equal β1-blocking doses. At higher plasma concentrations, though, metoprolol also blocks β2 receptors, and in overdose β1-selective agents lose their selectivity.
Genotype moves the line too. Nebivolol is β1-selective in CYP2D6 extensive metabolizers at lower doses, but blocks both β1 and β2 in poor metabolizers and at higher doses. CYP2D6 poor metabolizers also reach several-fold higher metoprolol levels, which erodes its cardioselectivity.
Intrinsic sympathomimetic activity (ISA) is partial agonism. In catecholamine-depleted animals, pindolol by itself raises myocardial inotropic and chronotropic activity; in people its ISA shows up as a smaller fall in resting heart rate and resting cardiac output than with drugs lacking ISA, while exercise tachycardia is still blunted. Acebutolol’s milder ISA lowers resting heart rate about 3 beats/min less than equivalent doses of propranolol, metoprolol or atenolol. ISA is not a safety net: the pindolol label finds no controlled evidence that it is safer in heart failure, heart block or bronchospasm.
Vasodilating β-blockers and membrane stabilization
Carvedilol is a racemate: the S(−) enantiomer blocks β receptors non-selectively, while both enantiomers block α1 with equal potency. Labetalol combines selective α1 blockade with non-selective β blockade; the α:β ratio is about 1:3 orally and 1:7 intravenously. Because α1 blockade dilates vessels, both drugs lower blood pressure more standing than supine, and labetalol lowers pressure without reflex tachycardia.
Nebivolol is a third-generation, β1-selective agent that dilates vessels a different way: through β3 agonism it stimulates endothelial nitric oxide synthase, and NO-mediated vasodilation lowers systemic vascular resistance. At clinically relevant doses it has no α1-blocking activity.
Membrane-stabilizing activity (MSA) is a quinidine-like, local-anesthetic-like sodium-channel effect. Propranolol shows it only at doses above those needed for β blockade, and its role in treating arrhythmias is uncertain; in overdose, sodium-channel-blocking β-blockers widen the QRS. Metoprolol and acebutolol show MSA only at concentrations far above clinical ones; atenolol, nadolol and pindolol lack it, and esmolol and nebivolol show none at therapeutic concentrations.
Comparing the drugs
Receptor profile
| Drug | β selectivity | ISA (partial agonism) | Added vasodilating action |
|---|---|---|---|
| Metoprolol | β1-selective; reduced at high concentrations and in CYP2D6 poor metabolizers | None | — |
| Atenolol | β1-selective | None | — |
| Carvedilol | Non-selective (S(−) enantiomer) | None | α1 blockade (both enantiomers) |
| Propranolol | Non-selective | None — no agonist activity | — |
| Labetalol | Non-selective | Minimal β1 ISA (β2 agonism in animals) | Selective α1 blockade; α:β about 1:3 oral, 1:7 IV |
| Nebivolol | β1-selective at lower doses in extensive metabolizers; non-selective in poor metabolizers and at higher doses | None | Nitric oxide via β3 agonism; no α1 blockade |
| Esmolol | β1-selective | None significant | — |
| Nadolol | Non-selective | None | — |
| Pindolol | Non-selective | Yes — smaller fall in resting heart rate and cardiac output | — |
| Acebutolol | β1-selective | Mild — resting heart rate falls about 3 beats/min less | — |
ISA = intrinsic sympathomimetic (partial agonist) activity. — = no added vasodilating mechanism described in the listed sources. β1-selective agents can lose their selectivity in overdose.
Pharmacokinetics at a glance
| Drug | Oral bioavailability | Main elimination | Half-life |
|---|---|---|---|
| Metoprolol | About 50% (first pass) | Hepatic, mainly CYP2D6; under 5% unchanged in urine | 3–4 h (7–9 h in CYP2D6 poor metabolizers) |
| Atenolol | About 50% absorbed | Renal, unchanged; little or no hepatic metabolism | 6–7 h |
| Carvedilol | 25–35% (first pass) | Hepatic (CYP2D6, CYP2C9); metabolites mainly in bile and feces | 7–10 h |
| Propranolol | About 25% (first pass) | Hepatic (CYP2D6, CYP1A2, CYP2C19); under 1% unchanged | 3–6 h immediate-release; about 10 h extended-release |
| Labetalol | 25% (first pass) | Hepatic glucuronidation; conjugates in urine and bile | 6–8 h oral; about 5.5 h IV |
| Nebivolol | Not determined | Glucuronidation and CYP2D6; urine and feces | Active d-nebivolol about 12 h (19 h in poor metabolizers) |
| Esmolol | IV only | Red-cell esterase hydrolysis | About 9 min |
| Nadolol | About 30% absorbed | Renal, unchanged; not metabolized | 20–24 h |
| Pindolol | Over 95%; no significant first pass | 35–40% unchanged in urine; the rest metabolized | 3–4 h |
| Acebutolol | About 40% (first pass to active diacetolol) | Renal 30–40%; nonrenal 50–60% | 3–4 h (diacetolol 8–13 h) |
Plasma elimination half-lives from the labels. Drugs that rely on the kidney (atenolol, nadolol, acebutolol’s metabolite diacetolol) last longer as renal function falls.
Pharmacokinetics
- First-pass metabolism — propranolol, carvedilol, labetalol, metoprolol, acebutolol
- Absorbed well but heavily extracted by the liver on the first pass, so oral bioavailability is low (see the table). Propranolol has a high hepatic extraction ratio, so liver blood flow matters: in cirrhosis its steady-state level rose about 2.5-fold. Hepatic impairment likewise raises labetalol’s bioavailability. Pindolol, with no significant first pass, is the exception.
- Lipid solubility and the CNS
- Propranolol is highly lipophilic and crosses the blood–brain barrier and the placenta; metoprolol reaches CSF at about 78% of the plasma concentration, and carvedilol is lipophilic. Atenolol, esmolol and acebutolol are relatively hydrophilic. Nadolol’s low lipophilicity goes with little brain penetration and a low incidence of CNS side effects, and only negligible labetalol crossed the blood–brain barrier in animals.
- Hepatic CYP metabolism — metoprolol, carvedilol, propranolol, nebivolol
- Metoprolol is primarily metabolized by CYP2D6; carvedilol by CYP2D6 and CYP2C9; propranolol by CYP2D6, CYP1A2 and CYP2C19; nebivolol mainly by direct glucuronidation and to a lesser extent by CYP2D6. Strong CYP2D6 inhibitors (quinidine, fluoxetine, paroxetine, propafenone) double metoprolol concentrations and reduce its cardioselectivity; fluoxetine raised d-nebivolol exposure (AUC) 8-fold.
- Renal elimination — atenolol, nadolol, acebutolol
- Atenolol undergoes little or no hepatic metabolism and is eliminated by the kidney; it accumulates significantly when creatinine clearance falls below 35 mL/min/1.73 m². Nadolol is not metabolized and is excreted unchanged, chiefly in urine, so its half-life lengthens in renal failure. Acebutolol’s own half-life is unchanged in renal impairment, but the half-life of its active metabolite diacetolol rises two- to three-fold.
- Ester hydrolysis — esmolol
- Hydrolyzed at its ester linkage by esterases in red-cell cytosol — not by plasma cholinesterase. Total clearance (about 20 L/kg/h) exceeds cardiac output, so liver and kidney blood flow do not limit it. The distribution half-life is about 2 minutes and the elimination half-life about 9 minutes; the acid metabolite, which has negligible activity (half-life about 3.7 h), is excreted in urine.
- Active metabolites and enantiomers — acebutolol, carvedilol, nebivolol, propranolol
- Acebutolol’s first-pass product diacetolol is equipotent (and in cats more cardioselective), so first-pass loss does not weaken the drug. Carvedilol’s 4′-hydroxyphenyl metabolite is about 13 times as potent at β receptors. Nebivolol’s glucuronide and hydroxyl metabolites add β-blocking activity. The S(−) enantiomer of propranolol is about 100 times as potent as the R(+) enantiomer.
- Protein binding and dialysis
- Carvedilol (over 98%), nebivolol (about 98%) and propranolol (about 90%) are highly protein-bound; atenolol (6–16%), metoprolol (about 10–12%) and acebutolol (about 26%) are not. Propranolol and labetalol are not significantly removed by dialysis, whereas acebutolol and diacetolol are dialyzable.
Pharmacogenomics
Uses & drug choice
- Hypertension & chronic stable angina
- Heart failure with reduced EF (carvedilol, metoprolol succinate)
- Rate control in atrial fibrillation; secondary prevention post-MI
- IV labetalol for severe hypertension (labetalol is also one of the most widely used drugs for hypertension in pregnancy, where acute treatment is a common off-label use)
- Esmolol for short-term IV control of rapid ventricular rate (SVT, atrial fibrillation/flutter) and of perioperative tachycardia and hypertension
- Acebutolol for ventricular premature beats
Adverse effects
- Bradycardia and AV block
- β1 blockade lengthens the sinus cycle at the SA node and prolongs conduction at the AV node. When conduction is already impaired, blockade also removes the sympathetic activity that was helping impulses through.
- Hypotension and dizziness
- Lower cardiac output, plus — for carvedilol and labetalol — α1-mediated vasodilation, so pressure falls more on standing. In carvedilol-treated CYP2D6 poor metabolizers, extra R(+) enantiomer means more dizziness during up-titration.
- Bronchospasm
- In patients prone to bronchospasm, blocking β2 removes endogenous adrenergic bronchodilator tone (passive bronchoconstriction) and can blunt exogenous β2 agonists. β1-selective agents lower FEV1 less, but their selectivity fades at higher concentrations.
- Masked hypoglycemia
- The tremor and palpitations of hypoglycemia are catecholamine-driven and are blunted. Sources differ on sweating: StatPearls’ Selective Beta-1 Blockers chapter says it remains unmasked and may be the only consistent sign (the acebutolol label likewise says sweating is usually not significantly affected), although StatPearls’ Propranolol chapter lists sweating among the adrenergic symptoms β-blockers can mask. β-blockade also takes away catecholamine-driven glycogenolysis and gluconeogenesis.
- Fatigue, sleep disturbance and other CNS effects
- Lipophilic agents — propranolol above all — cross the blood–brain barrier; insomnia, sleep changes and nightmares are more pronounced with drugs that do, and β-blockers lower melatonin secretion. Hydrophilic nadolol reaches the brain poorly, though even water-soluble atenolol can cause tiredness and fatigue.
- Cold extremities
- Reduced cardiac output plus peripheral vasoconstriction: β2 blockade removes cAMP-mediated vascular relaxation and leaves mild vasoconstriction. In patients with peripheral vascular disease, β-blockers can also worsen Raynaud phenomenon and intermittent claudication.
- Rebound after abrupt withdrawal
- Chronic blockade increases the number of β receptors, so stopping suddenly exposes more receptors to normal catecholamine levels — heightened sensitivity that can bring on angina, myocardial infarction or ventricular arrhythmias, and tremulousness, sweating, palpitations and headache even without coronary disease.
- Worsening acute heart failure
- A severely damaged heart may depend on sympathetic drive for adequate ventricular function, and blockade further depresses contractility. β-blockade can also raise oxygen demand by increasing left-ventricular fiber length and end-diastolic pressure, particularly in heart failure.
Toxicity & antidote
Overdose produces severe bradycardia, hypotension and cardiogenic shock, and can also bring AV block, heart failure, bronchospasm, impaired consciousness and hypoglycemia. Selectivity is lost at toxic doses, so β1-selective agents can also cause bronchospasm. Lipophilic drugs — propranolol most of all — enter the brain and can cause seizures and coma, and sodium-channel-blocking agents (membrane-stabilizing activity) widen the QRS.
Glucagon binds its own G-protein-coupled receptor, which signals through Gαs: adenylyl cyclase raises cAMP and activates PKA — the pathway the blocked β1 receptor would have used. Because this works independently of the β-adrenergic binding site, glucagon raises heart rate, contractility and AV conduction while β receptors stay occupied. β-agonists, by contrast, must compete with the blocker, and overdose can show marked resistance to adrenergic agents.
Other rescues follow the same logic: phosphodiesterase inhibitors (inamrinone, milrinone) increase cAMP, and high-dose insulin–euglycemia augments contractility. After propranolol, epinephrine can provoke uncontrolled hypertension through unopposed α stimulation. Water-soluble, renally excreted agents (atenolol, nadolol, acebutolol) may respond to hemodialysis, whereas propranolol is not significantly dialyzable.
Interactions
Contraindications
- Severe bradycardia or sick sinus syndrome (without a pacemaker) — The heart is already firing too slowly; further β1 blockade can drop the rate to a dangerous level.
- 2nd- or 3rd-degree AV block (without a pacemaker) — Slowing AV conduction on top of an existing conduction block can worsen the block and lead to hemodynamic compromise.
- Cardiogenic shock / acutely decompensated heart failure — A failing heart is leaning on sympathetic drive to maintain output. Removing that drive acutely can worsen the failure. (Beta-blockers help chronic, stable HFrEF — started low and slow once compensated.)
- Bronchial asthma with a non-selective agent (propranolol, nadolol, pindolol, labetalol, carvedilol); also related bronchospastic conditions with carvedilol, and any history of obstructive airway disease with labetalol — β2 blockade can trigger bronchospasm, and each of these drugs’ labels lists bronchial asthma as a contraindication (with carvedilol, deaths from status asthmaticus have followed single doses). The carvedilol label extends this to related bronchospastic conditions, and the labetalol labels say beta-blockers should not be used in anyone with a history of obstructive airway disease.
- COPD or other bronchospastic disease (agents other than labetalol and carvedilol); asthma when a β1-selective agent is considered use caution — β2 blockade can trigger bronchospasm. Labels advise that patients with bronchospastic disease generally should not receive beta-blockers; if one is needed, prefer a β1-selective agent at the lowest effective dose, and monitor respiratory status.
- Severe hepatic impairment (nebivolol, carvedilol) — Both labels list it as a contraindication. Nebivolol is metabolized mainly in the liver: moderate impairment alone raised exposure to its active isomer about 10-fold, and it has not been studied in severe impairment.
- IV verapamil (or another IV cardiodepressant calcium-channel blocker) given close in time to IV esmolol — Fatal cardiac arrests have occurred when IV esmolol and IV verapamil were given while the other drug’s cardiac effects were still present.
- Pulmonary hypertension (esmolol) — Esmolol may precipitate cardiorespiratory compromise.
- Severe, prolonged hypotension (labetalol) — Labetalol’s α1 blockade adds to its β-blocking effect in lowering blood pressure, and its labels list conditions with severe and prolonged hypotension as a contraindication.
High-yield
- C — carvedilol: α1 blockade dilates vessels
- L — labetalol: α1 blockade dilates vessels
- N — nebivolol: Nitric oxide (via β3 agonism) dilates vessels
Two dilate by α1 blockade, one by nitric oxide — and only the N drug is β1-selective.
- A — atenolol: eliminated by the kidney, little or no hepatic metabolism
- N — nadolol: not metabolized; excreted unchanged in urine
- A — acebutolol: its active metabolite diacetolol builds up when renal function falls
All three are water-soluble and may respond to hemodialysis in overdose. Atenolol and nadolol depend on the kidney; acebutolol is only 30–40% renally eliminated, but its metabolite diacetolol accumulates in renal impairment.
Practice questions
Q1A 34-year-old woman with mild intermittent asthma starts oral propranolol for migraine prophylaxis. Two weeks later she has wheezing and chest tightness, and her albuterol inhaler helps less than usual.
Which mechanism best explains her symptoms?
- A.Blockade of β1 receptors on bronchial smooth muscle
- B.Blockade of β2 receptors, removing cAMP-mediated relaxation of bronchial smooth muscle
- C.Direct stimulation of bronchial α1 receptors by propranolol
- D.A propranolol-induced rise in cAMP within bronchial smooth muscle
- E.Membrane-stabilizing (sodium-channel) blockade in airway smooth muscle
Show answer
B. Blockade of β2 receptors, removing cAMP-mediated relaxation of bronchial smooth muscle — β2 activation raises cAMP and activates PKA to relax bronchial smooth muscle. Non-selective propranolol blocks it, causing passive bronchoconstriction and interfering with exogenous bronchodilators such as albuterol; a rise in cAMP would relax the airway, not constrict it. Propranolol has no other autonomic activity (it does not stimulate α1 receptors), its membrane action appears only above β-blocking doses, and β1 receptors sit mainly in the heart — which is why β1-selective agents lower FEV1 less.
Q2A 29-year-old man is brought in 2 hours after intentionally swallowing his father’s propranolol. Heart rate is 38/min, blood pressure 70/40 mm Hg and blood glucose is low, and he has a generalized seizure. Atropine and IV fluids do not raise his heart rate or blood pressure.
The specific antidote for this overdose, given next, acts by which mechanism?
- A.Directly stimulating β1 receptors to outcompete propranolol
- B.Inhibiting phosphodiesterase to slow cAMP breakdown
- C.Blocking muscarinic receptors at the SA node
- D.Activating a Gs-coupled receptor distinct from the β receptor, raising cAMP through adenylyl cyclase
- E.Blocking cardiac sodium channels
Show answer
D. Activating a Gs-coupled receptor distinct from the β receptor, raising cAMP through adenylyl cyclase — This is β-blocker toxicity: bradycardia, hypotension and hypoglycemia, with seizures because lipophilic propranolol enters the brain. Glucagon is the antidote. It binds its own Gαs-coupled receptor, raising cAMP via adenylate cyclase and activating PKA independently of the β-adrenergic binding site. β-agonists must compete with the blocker, and overdose can resist adrenergic agents; raising cAMP by phosphodiesterase inhibition is how inamrinone and milrinone work; muscarinic blockade is atropine, which has already failed; and sodium-channel blockade (membrane-stabilizing activity) is a cause of QRS widening in overdose, not a treatment.
Q3A 62-year-old man starts immediate-release metoprolol after a myocardial infarction. On usual doses his resting heart rate drops to 44/min and he develops new wheeze. Genotyping shows he is a CYP2D6 poor metabolizer.
Which best explains his response?
- A.Faster conversion of metoprolol to a more potent active metabolite
- B.Accumulation of unchanged metoprolol from reduced renal excretion
- C.Intrinsic sympathomimetic activity unmasked at low drug levels
- D.Extra α1 blockade by the R(+) enantiomer
- E.Several-fold higher metoprolol levels, with loss of β1 selectivity
Show answer
E. Several-fold higher metoprolol levels, with loss of β1 selectivity — Metoprolol is cleared mainly by hepatic CYP2D6. Poor metabolizers reach several-fold higher concentrations, which deepens β1 blockade (bradycardia) and erodes cardioselectivity (β2 blockade, wheeze). Its metabolites appear to have no β-blocking activity, less than 5% of an oral dose is excreted unchanged, it has no ISA, and the α-blocking R(+) enantiomer belongs to carvedilol. CPIC advises starting poor metabolizers at the lowest recommended dose with careful titration and closer monitoring for bradycardia, or choosing another β-blocker.
Q4Two patients with hypertension start different oral β-blockers. Both drugs blunt exercise-induced tachycardia, but in one patient resting heart rate and resting cardiac output fall noticeably less than in the other.
The patient whose resting heart rate and cardiac output fall less is most likely taking which drug?
- A.Atenolol
- B.Metoprolol
- C.Nadolol
- D.Pindolol
- E.Propranolol
Show answer
D. Pindolol — Pindolol is a non-selective β-blocker with intrinsic sympathomimetic activity. As a partial agonist acting directly at the receptor, it still blunts exercise and isoproterenol tachycardia but lowers resting heart rate and resting cardiac output less than drugs lacking ISA. Atenolol, metoprolol, nadolol and propranolol have no ISA. Acebutolol also has ISA, but milder: about 3 beats/min less resting slowing.
Q5During emergence from anesthesia, a 70-year-old woman with cirrhosis develops atrial fibrillation with a ventricular rate of 150/min. The team wants a β-blocker whose effect will wear off within minutes if her blood pressure falls.
The drug chosen is short-acting chiefly because it is:
- A.Hydrolyzed by plasma cholinesterase
- B.Excreted unchanged by glomerular filtration
- C.Hydrolyzed by esterases in red-cell cytosol
- D.Glucuronidated in the liver with high first-pass extraction
- E.Oxidized by hepatic CYP2D6
Show answer
C. Hydrolyzed by esterases in red-cell cytosol — Esmolol is metabolized by hydrolysis of its ester linkage, chiefly by esterases in red-cell cytosol — not by plasma cholinesterase or red-cell membrane acetylcholinesterase. Its clearance exceeds cardiac output, so it does not depend on liver or kidney blood flow, and no special precautions are needed in hepatic impairment. The elimination half-life is about 9 minutes, with substantial recovery from blockade 10–20 minutes after the infusion stops.
Sources
- Beta Blockers — mechanism, adverse effects, contraindications — StatPearls (NCBI)
- Open RN Nursing Pharmacology — Ch. 4 Autonomic Nervous System (metoprolol & propranolol: apical pulse < 60 hold, masked hypoglycemia, taper) — Open RN (NCBI Bookshelf)
- Open RN Nursing Pharmacology — Ch. 6 Cardiovascular & Renal (hold parameters, metoprolol teaching: same time daily, no abrupt stop) — Open RN (NCBI Bookshelf)
- Metoprolol — mechanism, IV use and ECG monitoring, withdrawal syndrome, contraindications — StatPearls (NCBI)
- Propranolol — non-selective blockade, receptor upregulation on withdrawal, boxed warning removed 2021 — StatPearls (NCBI)
- Carvedilol — HFrEF, antianginal heart-rate target, verapamil/diltiazem interaction — StatPearls (NCBI)
- Esmolol — intravenous beta-1 blocker, onset within 60 seconds — StatPearls (NCBI)
- Heart Failure — compensatory sympathetic activation, remodeling, beta-blockers in HFrEF — StatPearls (NCBI)
- Stable Angina — oxygen supply–demand mismatch — StatPearls (NCBI)
- Physiology, Catecholamines — adrenal medulla and sympathetic nerve endings — StatPearls (NCBI)
- Physiology, Coronary Circulation — coronary flow peaks in diastole — StatPearls (NCBI)
- Essential Hypertension — sympathetic activation and peripheral resistance — StatPearls (NCBI)
- Open RN Nursing Skills — Ch. 1 General Survey (count the pulse for a full 60 seconds if irregular) — Open RN (NCBI Bookshelf)
- The use of stems in the selection of International Nonproprietary Names (-olol, -dilol) — World Health Organization
- Toprol-XL (metoprolol succinate) — current label: abrupt-cessation warning, hypoglycemia, contraindications (FDA label) — FDA / DailyMed
- Lopressor (metoprolol tartrate) — missed-dose counseling (FDA label) — FDA / DailyMed
- Tenormin (atenolol) — FDA label — FDA / DailyMed
- Coreg (carvedilol) — FDA label (alpha/beta blocker; dizziness after starting or increasing the dose) — FDA / DailyMed
- Inderal LA (propranolol extended-release) — FDA label — FDA / DailyMed
- Labetalol — alpha-1 plus non-selective beta blockade, hypertensive crises, off-label use in pregnancy, postural hypotension with IV dosing — StatPearls (NCBI)
- Nebivolol — β1 selectivity, nitric-oxide–mediated vasodilation, oral only, CYP2D6 metabolism — StatPearls (NCBI)
- Nadolol — non-selective, renal excretion, boxed warning on abrupt withdrawal — StatPearls (NCBI)
- Selective Beta-1 Blockers — cardioselective agents incl. esmolol, acebutolol, nebivolol; esmolol IV only — StatPearls (NCBI)
- Bystolic (nebivolol) — FDA label: hypertension, severe hepatic impairment contraindication, CYP2D6 inhibitors — FDA / DailyMed
- Brevibloc (esmolol) injection — FDA label: short-term IV use, contraindications, infusion-site reactions, hypotension — FDA / DailyMed
- Labetalol hydrochloride tablets (Zydus) — FDA label: hepatic injury, scalp tingling, contraindications — FDA / DailyMed
- Labetalol hydrochloride injection (Hospira) — FDA label: keep supine, postural hypotension, line compatibility, lab-test interference — FDA / DailyMed
- Nadolol tablets (Unichem) — FDA label: boxed warning on abrupt withdrawal, renal excretion, contraindications — FDA / DailyMed
- Pindolol tablets (ANI) — FDA label: intrinsic sympathomimetic activity, contraindications — FDA / DailyMed
- Acebutolol hydrochloride capsules (ANI) — FDA label: cardioselective with mild ISA, renal dosing, α-stimulant decongestants — FDA / DailyMed
- Beta 1 Receptors — Gs, adenylyl cyclase, PKA and calcium; renin release — StatPearls (NCBI)
- Alpha-1 Receptor Agonists — Gq, phospholipase C, IP3/DAG, vascular smooth muscle contraction — StatPearls (NCBI)
- Beta-Blocker Toxicity — loss of selectivity, lipophilicity, membrane-stabilizing activity, dialysis — StatPearls (NCBI)
- Glucagon — glucagon receptor, adenylate cyclase, positive inotropy — StatPearls (NCBI)
- Brevibloc (esmolol) — red-cell esterase metabolism, 9-minute half-life (FDA label) — FDA / DailyMed
- Nadolol tablets (Amneal) — clinical pharmacology, renal excretion (FDA label) — FDA / DailyMed
- Pindolol tablets (Sun Pharma) — intrinsic sympathomimetic activity, pharmacokinetics (FDA label) — FDA / DailyMed
- Acebutolol capsules (Amneal) — cardioselectivity, mild ISA, diacetolol (FDA label) — FDA / DailyMed
- Table of Pharmacogenomic Biomarkers in Drug Labeling (CYP2D6: carvedilol, metoprolol, nebivolol, propranolol) — U.S. Food and Drug Administration
- CPIC® guideline for CYP2D6, ADRB1, ADRB2, ADRA2C, GRK4, GRK5 and beta-blockers (2024) — CPIC (ClinPGx)
By LearnDrugs
Educational summary for medical students. Always verify against current prescribing information and guidelines. Not medical advice.