Drug Monograph
Metoprolol Tartrate
Lopressor
Pharmacokinetic Profile
Half-Life
3–4 h (EM); 7–9 h (PM)
Metabolism
Hepatic (CYP2D6)
Protein Binding
~12%
Bioavailability
~50% (oral)
Volume of Distribution
3.2–5.6 L/kg
Clinical Information
Drug Class
Cardioselective beta-blocker
Available Doses
25, 37.5, 50, 75, 100 mg tabs; 5 mg/5 mL IV
Route
Oral, IV
Renal Adjustment
Not required
Hepatic Adjustment
Reduce dose; prolonged t½
Pregnancy
No established risk (limited human data)
Lactation
Excreted in breast milk (small amounts)
Schedule / Legal Status
Rx only (not scheduled)
Generic Available
Yes
Approved Indications & Off-Label Uses
| Indication | Approved Population | Therapy Type | Status |
|---|---|---|---|
| Hypertension | Adults | Monotherapy or combination | FDA Approved |
| Angina pectoris (chronic stable) | Adults | Monotherapy or combination | FDA Approved |
| Acute myocardial infarction (hemodynamically stable) | Adults | Adjunctive (IV then oral) | FDA Approved |
Metoprolol tartrate is one of the most widely prescribed cardioselective beta-blockers globally. Its three FDA-approved indications span the spectrum of common cardiovascular conditions. In hypertension, it reduces blood pressure through decreased cardiac output and suppression of renin release. In stable angina, it lowers myocardial oxygen demand by reducing heart rate and contractility. In the post-MI setting, early use reduces cardiovascular mortality, as demonstrated in the landmark MIAMI trial.
Off-Label Uses
Rate control in atrial fibrillation/flutter — Commonly used for acute and chronic ventricular rate control; well-supported by AHA/ACC/HRS guidelines. Evidence quality: High.
Supraventricular tachycardia (SVT) — IV metoprolol can terminate or slow SVT when vagal maneuvers and adenosine fail. Evidence quality: Moderate.
Migraine prophylaxis — Supported by multiple RCTs and AAN guidelines as a level A recommendation (though tartrate salt specifically less studied than the succinate formulation). Evidence quality: Moderate.
Thyrotoxicosis symptom control — Used adjunctively to control adrenergic symptoms (tachycardia, tremor) in thyroid storm and hyperthyroidism. Evidence quality: Moderate.
Performance anxiety — Low-dose use before public speaking or performance situations to reduce heart rate and tremor. Evidence quality: Low.
Dosing by Clinical Scenario
Adult Dosing
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| Essential hypertension — initial monotherapy | 50 mg BID | 100–200 mg BID | 450 mg/day | Take with or immediately after meals; titrate at weekly intervals Once-daily dosing may be attempted but may not maintain BP control over full 24 hours at lower doses |
| Hypertension — add-on to thiazide diuretic | 50 mg BID | 100–200 mg/day | 450 mg/day | Additive BP reduction with diuretics; monitor for orthostatic hypotension |
| Chronic stable angina | 50 mg BID | 100–200 mg BID | 400 mg/day | Titrate to resting HR 55–60 bpm; taper over 1–2 weeks if discontinuing Antianginal effect is related to the logarithm of the plasma concentration |
| Acute MI — early intervention (hemodynamically stable) | 5 mg IV x 3 doses | 50 mg PO q6h x 48 h, then 100 mg BID | 200 mg/day (oral maintenance) | Give IV boluses at 2-min intervals; monitor HR, BP, ECG during IV dosing If patient does not tolerate full IV dose, start oral at 25 mg q6h |
| Acute rate control — AF/SVT (off-label) | 2.5–5 mg IV over 2 min | 25–100 mg PO BID | 15 mg IV (acute); 400 mg/day PO | May repeat IV every 5 min up to 3 doses; transition to oral once rate controlled Target resting ventricular rate per AHA/ACC guidelines |
| Thyrotoxicosis — adrenergic symptom control (off-label) | 25–50 mg PO BID–QID | Titrate to symptom control | 400 mg/day | Higher doses may be needed due to increased metoprolol clearance in hyperthyroid states |
Special Populations
| Population | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| Elderly (≥65 years) | 25 mg BID | Titrate slowly | Standard adult max | Increased sensitivity possible; start low and titrate based on HR and BP response |
| Hepatic impairment | 25 mg BID | Titrate cautiously | Individualize | Half-life markedly prolonged (up to 7.2 h); bioavailability increased; start at reduced doses Cirrhosis with portal shunting significantly increases systemic exposure |
| CYP2D6 poor metabolizers | 25 mg BID | Titrate to effect | Individualize | Plasma levels several-fold higher; t½ 7–9 h; reduced cardioselectivity at higher exposures ~8% of Caucasians and ~2% of most other populations are CYP2D6 poor metabolizers |
| Renal impairment | No dose adjustment required. Metoprolol is primarily hepatically cleared; renal impairment does not significantly alter systemic availability or half-life. | |||
Clinical Pearl: Tartrate vs. Succinate
Metoprolol tartrate is an immediate-release formulation requiring BID–TID dosing. Metoprolol succinate is the extended-release formulation dosed once daily. The two salts are not interchangeable on a milligram-for-milligram basis (100 mg tartrate approximately equals 95 mg succinate). For heart failure specifically, only metoprolol succinate (not tartrate) has an FDA-approved indication, based on the MERIT-HF trial data. When switching between formulations, maintain the same total daily dose and confirm with the patient.
Pharmacology
Mechanism of Action
Metoprolol is a selective beta-1 adrenergic receptor antagonist. It competes with endogenous catecholamines (epinephrine and norepinephrine) for binding at beta-1 receptors located predominantly in cardiac tissue. By occupying these receptors without triggering downstream signalling, metoprolol reduces heart rate (negative chronotropy), myocardial contractility (negative inotropy), and conduction velocity through the AV node (negative dromotropy). These combined effects lower cardiac output and myocardial oxygen consumption, which underpins its efficacy in hypertension and angina. Metoprolol also suppresses renin secretion from the juxtaglomerular apparatus, contributing an additional antihypertensive mechanism. At therapeutic doses, its selectivity for beta-1 over beta-2 receptors means bronchial and vascular smooth muscle beta-2 receptors are relatively spared, though this selectivity diminishes at higher plasma concentrations.
ADME Profile
| Parameter | Value | Clinical Implication |
|---|---|---|
| Absorption | Rapid and complete; Tmax 1–2 h; ~50% bioavailability due to first-pass metabolism | Take with meals to standardize absorption; bioavailability may increase to 70–80% with chronic dosing as hepatic first-pass becomes saturated |
| Distribution | Vd 3.2–5.6 L/kg; protein binding ~12% (albumin); crosses blood-brain barrier and placenta | Extensive tissue distribution; CNS penetration accounts for central side effects (depression, nightmares); low protein binding means minimal displacement interactions |
| Metabolism | Hepatic via CYP2D6 (O-demethylation ~65%, alpha-hydroxylation ~10%); metabolites inactive | CYP2D6 polymorphism causes wide inter-patient variability; poor metabolizers have 3–5-fold higher plasma levels; CYP2D6 inhibitors can functionally convert extensive metabolizers to poor metabolizer phenotype |
| Elimination | t½ 3–4 h (EM), 7–9 h (PM); 95% recovered in urine; <10% as unchanged drug (EM) | No renal dose adjustment needed; hepatic impairment significantly prolongs elimination; poor metabolizers excrete up to 30–40% unchanged drug renally |
Metoprolol Tartrate Side Effects
≥10%
Very Common
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Tiredness / fatigue | ~10% | Most common complaint; typically dose-related and may improve over the first few weeks of therapy; advise patients to avoid operating heavy machinery until response is known |
| Dizziness | ~10% | Related to blood pressure reduction; worse with position changes; counsel patients to rise slowly from sitting or lying |
1–10%
Common
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Depression | ~5% | Screen at follow-up; recent data suggest beta-blockers may contribute to sleep disturbances more than overt depression; consider switching to a less lipophilic agent if problematic |
| Diarrhea | ~5% | Usually self-limiting; ensure adequate hydration; persistent symptoms warrant evaluation for other causes |
| Pruritus / rash | ~5% | Distinguish from true hypersensitivity; if urticaria or angiedema develop, discontinue immediately |
| Bradycardia | 1–10% | Expected pharmacologic effect; clinically significant if HR <50 bpm with symptoms; reduce dose or hold if symptomatic |
| Cold extremities | 1–5% | Peripheral vasoconstriction from beta-2 antagonism at higher doses; more troublesome in patients with Raynaud phenomenon or peripheral vascular disease |
| Shortness of breath | ~1% | More common in patients with underlying reactive airway disease; distinguish from worsening heart failure; may necessitate dose reduction or drug switch |
| Nausea / abdominal discomfort | ~1% | Taking with food usually mitigates GI symptoms; reassess if persistent |
| Insomnia / nightmares | 1–5% | Related to CNS penetration of metoprolol tartrate (lipophilic); may improve with AM dosing or switch to a hydrophilic beta-blocker (e.g., atenolol) |
Serious
Serious (Regardless of Frequency)
| Adverse Effect | Estimated Frequency | Typical Onset | Required Action |
|---|---|---|---|
| Severe bradycardia (HR <40 bpm) | Up to 15.9% (MI setting) | Hours to days after initiation | Hold metoprolol; atropine 0.5–1 mg IV for acute symptomatic bradycardia; consider temporary pacing if refractory |
| Symptomatic hypotension (SBP <90 mmHg) | Up to 27.4% (MI setting) | Minutes to hours after IV dosing | Withhold further doses; Trendelenburg position; IV fluids; vasopressors if needed |
| Worsening heart failure | Up to 27.5% (MI setting) | Days to weeks | Increase diuretics; reduce or temporarily discontinue metoprolol; restore clinical stability before retitration |
| Second- or third-degree heart block | Uncommon (1–5% in MI setting) | Hours to days | Discontinue metoprolol; atropine or isoproterenol for acute block; evaluate need for temporary or permanent pacing |
| Bronchospasm | Rare (<1%) | Any time, more likely at higher doses | Administer beta-2 agonist bronchodilator; discontinue metoprolol; cardioselective advantage is lost at high doses |
| Cardiogenic shock | Rare (in acute MI context) | Within hours of IV loading | Emergency care; IV glucagon 3–10 mg bolus; vasopressors; inotropic support |
| Rebound angina / MI on abrupt withdrawal | Rare (if tapered properly) | 1–7 days after sudden discontinuation | Reinstate metoprolol promptly; gradual taper over 1–2 weeks is mandatory when discontinuing |
Discontinuation
Discontinuation Data
Hypertension / Angina Trials
~5% discontinuation rate
Top reasons: Fatigue, dizziness, depression, gastrointestinal disturbance, cold extremities
Acute MI Trials
Higher rates due to hemodynamic events
Top reasons: Hypotension, bradycardia, worsening heart failure, dyspnea
| Reason for Discontinuation | Incidence | Context |
|---|---|---|
| Fatigue / tiredness | ~2% | Most common reason in chronic use trials; often subsides over first weeks |
| Dizziness / hypotension | ~1–2% | More prominent at initiation; dose reduction often resolves |
| Depression / mood changes | ~1% | May be underreported; ask specifically at follow-up visits |
| GI symptoms | <1% | Nausea, diarrhea; usually resolve with food co-administration |
| Bradycardia | <1% (chronic use) | Clinically significant bradycardia requiring discontinuation is uncommon in hypertension trials |
Managing Fatigue — The Most Impactful Side Effect on Adherence
Fatigue is the leading cause of patient-initiated discontinuation. Before switching agents, ensure the patient is taking metoprolol tartrate with meals (improves tolerability), consider reducing the dose if blood pressure allows, and explore whether the fatigue might be attributable to other causes (anemia, depression, sleep apnea). If fatigue remains intolerable, consider switching to a vasodilating beta-blocker (nebivolol or carvedilol) or a non-beta-blocker antihypertensive.
Drug Interactions
Metoprolol tartrate is primarily metabolized by CYP2D6. Its most clinically significant interactions involve CYP2D6 inhibitors (which increase metoprolol exposure severalfold), other negative chronotropes, and agents that mask hypoglycemia. Approximately 8% of Caucasians are CYP2D6 poor metabolizers, in whom these interactions may be further amplified.
Major
Verapamil / Diltiazem
MechanismAdditive AV node depression and negative inotropy
EffectSevere bradycardia, heart block, and heart failure
ManagementAvoid IV combination; if oral co-use is essential, monitor ECG and heart function closely
FDA PI
Major
Clonidine (on withdrawal)
MechanismUnopposed alpha-adrenergic stimulation when clonidine is discontinued while beta-blocker continues
EffectSevere rebound hypertension
ManagementWithdraw metoprolol several days before tapering clonidine; when substituting, delay metoprolol initiation until clonidine has been stopped for several days
FDA PI
Major
Propafenone / Quinidine
MechanismPotent CYP2D6 inhibition; propafenone also has intrinsic beta-blocking properties
EffectMetoprolol plasma concentrations increased 2–5-fold (propafenone) or 3-fold (quinidine); loss of cardioselectivity; excessive beta-blockade
ManagementReduce metoprolol dose substantially; monitor HR and BP frequently; consider alternative antiarrhythmic
FDA PI
Major
Fluoxetine / Paroxetine
MechanismStrong CYP2D6 inhibition by SSRI increases metoprolol exposure
EffectElevated metoprolol levels with enhanced beta-blockade, possible bradycardia and hypotension
ManagementUse a non-CYP2D6-dependent SSRI (e.g., sertraline, citalopram, escitalopram) or monitor HR/BP closely and reduce metoprolol dose as needed
FDA PI / Lexicomp
Moderate
Digoxin
MechanismAdditive slowing of AV conduction
EffectIncreased risk of bradycardia and AV block
ManagementMonitor heart rate and ECG periodically; adjust doses based on rate response
FDA PI
Moderate
Insulin / Sulfonylureas
MechanismBeta-blockade masks adrenergic hypoglycemia symptoms (tachycardia, tremor) and may impair glycogenolysis
EffectDelayed recognition of hypoglycemia; sweating often remains as a preserved warning sign
ManagementEducate patients to rely on sweating and hunger as hypoglycemia cues; monitor blood glucose more frequently at initiation
FDA PI
Moderate
NSAIDs (e.g., ibuprofen, naproxen)
MechanismProstaglandin inhibition reduces renal sodium excretion, opposing antihypertensive effect
EffectBlunted blood pressure reduction; possible fluid retention
ManagementMonitor blood pressure; use the lowest effective NSAID dose for the shortest duration; consider paracetamol as alternative analgesic
FDA PI
Moderate
Hydralazine
MechanismHydralazine inhibits presystemic metabolism of metoprolol
EffectIncreased metoprolol plasma concentrations
ManagementMonitor HR and BP when initiating or adjusting hydralazine dose; dose reduction of metoprolol may be needed
FDA PI
Minor
Diphenhydramine
MechanismModerate CYP2D6 inhibition
EffectMild increase in metoprolol exposure
ManagementClinically meaningful interaction is unlikely at usual OTC doses; monitor for excessive beta-blockade with regular co-administration
Lexicomp
Minor
Rifampicin
MechanismHepatic enzyme induction increases metoprolol clearance
EffectReduced metoprolol efficacy; blood pressure and heart rate may be suboptimally controlled
ManagementMonitor blood pressure; higher metoprolol doses may be needed during co-administration
LexicompMonitoring Parameters
-
Heart Rate
Every visit
Routine Target resting HR typically 55–65 bpm for angina/rate control; hold or reduce dose if HR <50 bpm with symptoms. During IV loading in acute MI, monitor continuously. -
Blood Pressure
Every visit; daily at home during titration
Routine Measure near the end of the dosing interval (trough) to assess 24-hour coverage. If on once-daily regimen, verify adequacy of end-of-dose control. -
ECG
Baseline; repeat if symptomatic
Trigger-based Assess PR interval at baseline to rule out pre-existing conduction delays. Repeat if patient develops syncope, pre-syncope, or new palpitations. Continuous monitoring required during IV dosing. -
Blood Glucose
Periodically in diabetics
Routine Beta-blockers may mask tachycardia associated with hypoglycemia. Counsel diabetic patients to recognize non-adrenergic signs of low blood sugar such as sweating and hunger. -
Signs of Heart Failure
Each visit during titration
Trigger-based Assess for weight gain, peripheral edema, dyspnea on exertion, and JVP elevation. If new signs emerge, increase diuretics and consider reducing or holding metoprolol. -
Hepatic Function
Baseline in high-risk patients
Trigger-based Metoprolol is hepatically cleared; patients with cirrhosis or significant liver disease may require reduced dosing. Repeat LFTs if hepatitis is clinically suspected. -
Mood / Depression
At follow-up visits
Routine Screen for depressive symptoms, sleep disturbance, and fatigue. Ask specifically, as patients may not volunteer CNS-related side effects.
Contraindications & Cautions
Absolute Contraindications
- Severe sinus bradycardia (HR <45 bpm)
- Second- or third-degree heart block without a functioning pacemaker
- Significant first-degree heart block (PR interval ≥0.24 sec) — for IV formulation in acute MI
- Cardiogenic shock or decompensated heart failure requiring IV inotropes
- Sick sinus syndrome without a functioning pacemaker
- SBP <100 mmHg — for IV formulation in acute MI setting
- Known hypersensitivity to metoprolol, other beta-blockers, or any excipient
Relative Contraindications (Specialist Input Recommended)
- Compensated heart failure — metoprolol tartrate is not FDA-approved for heart failure; if beta-blocker therapy is indicated, metoprolol succinate XL is preferred with careful up-titration
- Peripheral vascular disease with symptomatic claudication — beta-blockade may worsen symptoms, though evidence of significant harm is limited
- Pheochromocytoma — must initiate alpha-blocker therapy first to prevent unopposed alpha-mediated vasoconstriction and hypertensive crisis
- Prinzmetal (variant) angina — beta-blockade may promote coronary vasospasm; use calcium channel blocker instead
Use with Caution
- Diabetes mellitus — may mask hypoglycemic symptoms (tachycardia, tremor) and may impair glucose tolerance
- Thyrotoxicosis — abrupt withdrawal may precipitate thyroid storm; taper gradually
- Bronchospastic disease — avoid beta-blockers if possible; if essential, use lowest effective dose with a beta-2 agonist available; cardioselectivity is dose-dependent and diminishes at higher plasma levels
- Major surgery — do not routinely withdraw chronic beta-blocker therapy before surgery, but avoid initiating high-dose extended-release metoprolol perioperatively (POISE trial concern)
- Hepatic impairment — increased exposure due to reduced first-pass metabolism; use reduced starting doses
- Elderly patients — may have increased sensitivity to beta-blockade; start at lower doses
FDA Class-Wide Regulatory Warning
Abrupt Cessation of Beta-Blocker Therapy
Abrupt discontinuation of metoprolol tartrate in patients with coronary artery disease has been associated with severe exacerbation of angina pectoris, myocardial infarction, and ventricular arrhythmias. When discontinuing chronic therapy, the dosage should be gradually reduced over 1 to 2 weeks with close clinical monitoring. Patients should be advised against interrupting or stopping therapy without medical guidance. If withdrawal symptoms emerge, metoprolol should be reinstated promptly, at least temporarily.
Patient Counselling
Purpose of Therapy
Metoprolol tartrate helps lower blood pressure and heart rate, reducing the workload on your heart. Depending on your condition, it may be used to manage high blood pressure, prevent chest pain (angina), or protect your heart after a heart attack. It works by slowing the heart and allowing blood vessels to relax, which improves blood flow.
How to Take
Take metoprolol tartrate tablets with meals or immediately after eating, as this helps your body absorb the medication consistently and reduces the chance of stomach upset. Take it at the same times each day, usually once or twice daily as prescribed. Do not skip doses and do not stop taking this medication abruptly — your doctor will taper the dose gradually if it needs to be discontinued.
Fatigue & Tiredness
Tell patient
Feeling tired is the most common side effect and usually improves as your body adjusts over the first few weeks. Plan activities for when you have the most energy. Avoid driving or operating heavy machinery until you know how this medication affects you.
Call prescriber
If tiredness is severe, does not improve after 2–3 weeks, or interferes significantly with daily activities.
Dizziness & Lightheadedness
Tell patient
This medication can lower your blood pressure, which may cause dizziness especially when standing up quickly. Rise slowly from sitting or lying positions. Sit or lie down immediately if you feel dizzy or faint.
Call prescriber
If dizziness is frequent, causes falls, or is accompanied by fainting episodes.
Never Stop Suddenly
Tell patient
Stopping metoprolol abruptly can cause a dangerous rebound effect, including worsening chest pain, heart attack, or dangerously high blood pressure. Always consult your doctor before making any changes to your dose. If you run out of medication, contact your pharmacy or prescriber immediately for a refill.
Call prescriber
If you have missed several doses or have run out of medication and cannot get a refill, or if you develop chest pain or a racing heartbeat after missing doses.
Blood Sugar Monitoring (Diabetic Patients)
Tell patient
This medication can mask some typical signs of low blood sugar, particularly a fast heartbeat. Sweating and hunger will still occur as warning signs. Check your blood sugar more frequently when you first start this medication or when doses change.
Call prescriber
If you experience more frequent or severe episodes of low blood sugar, or if your diabetes becomes harder to control.
Cold Hands & Feet
Tell patient
Some patients notice their hands and feet feel colder than usual. This is because the medication can slightly reduce blood flow to the extremities. Wear warm gloves and socks in cold weather.
Call prescriber
If fingers or toes change color (white, blue, then red), become painful, or if you develop sores on your extremities.
Weight Gain & Breathing Difficulty
Tell patient
Monitor your weight at home. A sudden increase in weight (more than 1–2 kg over a few days) combined with swelling in the legs or increasing shortness of breath could indicate a change in heart function that needs attention.
Call prescriber
Urgently if you develop sudden shortness of breath at rest, rapid weight gain with ankle swelling, or you need to sleep propped up on extra pillows to breathe comfortably.
Sources
Regulatory (PI / SmPC)
- Lopressor (metoprolol tartrate) tablets and injection — FDA-approved prescribing information (2023 revision). accessdata.fda.gov Primary regulatory source for approved indications, dosing, contraindications, adverse reactions, and pharmacokinetics of the tartrate formulation.
- Metoprolol tartrate tablets — FDA structured product label (Mylan Pharmaceuticals). fda.gov Updated generic labeling confirming dosing ranges, available tablet strengths (25, 37.5, 50, 75, 100 mg), and adverse reaction incidence data.
- Toprol-XL (metoprolol succinate) extended-release tablets — FDA prescribing information (2023). accessdata.fda.gov Cross-reference for pharmacokinetic comparison between tartrate and succinate formulations and heart failure indication (succinate only).
Key Clinical Trials
- The MIAMI Trial Research Group. Metoprolol in acute myocardial infarction (MIAMI): a randomised placebo-controlled international trial. Eur Heart J. 1985;6(3):199–226. doi:10.1093/oxfordjournals.eurheartj.a061845 Landmark trial showing 36% reduction in 3-month mortality with early IV then oral metoprolol tartrate in acute MI (n=1,395).
- MERIT-HF Study Group. Effect of metoprolol CR/XL in chronic heart failure: Metoprolol CR/XL Randomised Intervention Trial in Congestive Heart Failure (MERIT-HF). Lancet. 1999;353(9169):2001–2007. doi:10.1016/S0140-6736(99)04440-2 Established 34% mortality reduction with metoprolol succinate CR/XL in NYHA II–IV heart failure; note this trial used the succinate salt, not the tartrate.
- Poole-Wilson PA, Swedberg K, Cleland JG, et al. Comparison of carvedilol and metoprolol on clinical outcomes in patients with chronic heart failure in the Carvedilol Or Metoprolol European Trial (COMET). Lancet. 2003;362(9377):7–13. doi:10.1016/S0140-6736(03)13800-7 Head-to-head trial showing carvedilol superiority over metoprolol tartrate in chronic heart failure; limitations include potentially suboptimal tartrate dosing.
Guidelines
- Whelton PK, Carey RM, Aronow WS, et al. 2017 ACC/AHA Guideline for the Prevention, Detection, Evaluation, and Management of High Blood Pressure in Adults. J Am Coll Cardiol. 2018;71(19):e127–e248. doi:10.1016/j.jacc.2017.11.006 Current US hypertension guideline; beta-blockers are not first-line for uncomplicated hypertension but remain indicated for compelling indications (post-MI, rate control, angina).
- January CT, Wann LS, Calkins H, et al. 2019 AHA/ACC/HRS Focused Update of the 2014 Guideline for Management of Patients with Atrial Fibrillation. J Am Coll Cardiol. 2019;74(1):104–132. doi:10.1016/j.jacc.2019.01.011 Supports use of beta-blockers including metoprolol for ventricular rate control in atrial fibrillation.
- Silberstein SD, Holland S, Freitag F, et al. Evidence-based guideline update: Pharmacologic treatment for episodic migraine prevention in adults. Neurology. 2012;78(17):1337–1345. doi:10.1212/WNL.0b013e3182535d20 AAN guideline establishing metoprolol as a Level A recommendation for migraine prophylaxis.
Mechanistic / Basic Science
- Lennard MS. Metoprolol: CYP2D6 polymorphisms and stereoselective metabolism. In: Kalow W, Meyer UA, Tyndale RF, eds. Pharmacogenomics. 2nd ed. CRC Press; 2005. Comprehensive review of CYP2D6-dependent stereoselective metabolism of metoprolol and clinical implications for poor vs. extensive metabolizers.
Pharmacokinetics / Special Populations
- Regårdh CG, Johnsson G. Clinical pharmacokinetics of metoprolol. Clin Pharmacokinet. 1980;5(6):557–569. doi:10.2165/00003088-198005060-00004 Foundational PK study establishing bioavailability (~50%), protein binding (~10%), Vd, and the impact of hepatic impairment on metoprolol clearance.
- Blake CM, Kharasch ED, Schwab M, Nagele P. A meta-analysis of CYP2D6 metabolizer phenotype and metoprolol pharmacokinetics. Clin Pharmacol Ther. 2013;94(3):394–399. doi:10.1038/clpt.2013.96 Meta-analysis quantifying the impact of CYP2D6 polymorphisms on metoprolol exposure across metabolizer phenotypes.
- Devereaux PJ, Yang H, Yusuf S, et al. Effects of extended-release metoprolol succinate in patients undergoing non-cardiac surgery (POISE trial). Lancet. 2008;371(9627):1839–1847. doi:10.1016/S0140-6736(08)60601-7 Key perioperative trial demonstrating that initiating high-dose extended-release metoprolol shortly before non-cardiac surgery increased stroke and death risk despite reducing MI.