Dosing and uses of Lopressor, Toprol XL (metoprolol)
Adult dosage forms and strengths
injectable solution (as tartrate)
- 1mg/mL
tablet (as tartrate)
- 25mg
- 50mg
- 100mg
tablet, extended-release (as succinate)
- 25mg
- 50mg
- 100mg
- 200mg
Acute Myocardial Infarction
Early treatment
metoprolol tartrate (Lopressor)
- 5 mg rapid IV q2min, up to 3 doses; then, 15 minutes after last IV, 50 mg PO q6hr for 48 hours; then 50-100 mg PO q12hr
- If full IV dose not tolerated: 25-50 mg PO q6hr after last IV
Congestive Heart Failure
metoprolol succinate (Toprol XL)
- 25 mg PO qDay initially; increased every 2 weeks PRN; target dosage, 200 mg/day
- New York Heart Association (NYHA) class ≥II: Reduce dosage 12.5 mg/day
Hypertension
metoprolol tartrate (Lopressor)
- 100 mg/day PO initially in single dose or divided q12hr; may be increased at intervals of 1 week or longer; not to exceed 450 mg/day
metoprolol succinate (Toprol XL)
- 25-100 mg PO qDay initially; may be increased at intervals of 1 week or longer; usual range, 50-100 mg/day; not to exceed 400 mg/day
Angina
metoprolol tartrate (Lopressor)
- 100 mg/day PO initially divided q12hr; may be increased at intervals of 1 week or longer; not to exceed 400 mg/day
metoprolol succinate (Toprol XL)
- 100 mg/day PO initially; may be increased at intervals of 1 week or longer; not to exceed 400 mg/day
Hyperthyroidism
25-50 mg PO q6hr
Acute Tachyarrhythmia (Off-label)
5 mg IV over 1-2 minutes q5min; total dose not to exceed 15 mg
Migraine (Off-label)
Prophylaxis
Metoprolol tartrate: 50-100 mg PO q12hr
Atrial Fibrillation/Flutter or Supraventricular Tachycardia (Off-label)
2.5-5 mg IV q2-5min; not to exceed 15 mg over 10-15 minutes; maintenance: 25-100 mg PO q12hr
Hepatic impairment
Consider initiating extended release tablet at doses lower than those recommended; gradually increase dosage to optimize therapy, while monitoring closely for adverse events
Dosing Considerations
In switching from immediate-release to extended-release, same total daily dose of metoprolol should be used
In switching between oral and IV dosage forms, equivalent beta-blocking effect is achieved in 2.5:1 (oral-to-IV) ratio
Take with or immediately following meals metoprolol tartrate: Take with or immediately after meals
Metoprolol succinate: Tablet should not be chewed or crushed
Dosing Modifications
Renal impairment: Dosage adjustment is not necessary
Hepatic impairment: Not studied; lower dosage may be necessary
Pediatric dosage forms and strengths
injectable solution (as tartrate)
- 1mg/mL
tablet, immediate-release (as tartrate)
- 25mg
- 50mg
- 100mg
tablet, extended-release (as succinate)
- 25mg
- 50mg
- 100mg
- 200mg
Hypertension
metoprolol tartrate (Lopressor)
- 1-17 years: 1-2 mg/kg/day PO divided BID; not to exceed 6 mg/kg/day or ≤200 mg/day
metoprolol succinate (Toprol XL)
- ≥6 years: 1 mg/kg PO qDay; not to exceed 50 mg/day initially; adjusted on basis of patient response; not to exceed 2 mg/kg/day or ≤200 mg/day
Geriatric dosage forms and strengths
Use lower dosage in management of hypertension
Lopressor, Toprol XL (metoprolol) adverse (side) effects
1-10%
Dizziness (10%)
Headache (10%)
Tiredness (10%)
Depression (5%)
Diarrhea (5%)
Pruritus (5%)
Bradycardia (9%)
Rash (5%)
Dyspnea (1-3%)
Cold extremities (1%)
Constipation (1%)
Dyspepsia (1%)
Heart failure (1%)
Hypotension (1%)
Nausea (1%)
Flatulence (1%)
Heartburn (1%)
Xerostomia (1%)
Wheezing (1%)
Bronchospasm (1%)
Frequency not defined
Decreased exercise tolerance
Raynaud phenomenon
Increased triglyceride levels and insulin resistance, decreased high-density lipoprotein (HDL) levels
Postmarketing reports
Anxiety/nervousness
Hallusinations
Paresthesia
Hepatitis
Vomiting
Arthralgia
Male impotence
Reversible alopecia
Agranulocytosis
Dry eyes
Worsening of psoriasis
Pyronie’s disease
Sweating
Photosensitivity
Taste disturbance
Warnings
Black box warnings
Ischemic heart disease may be exacerbated after abrupt withdrawaL
Hypersensitivity to catecholamines has been observed during withdrawaL
Exacerbation of angina and, in some cases, myocardial infarction (MI) may occur after abrupt discontinuance
When long-term beta blocker therapy (particularly with ischemic heart disease) is discontinued, dosage should be gradually reduced over 1-2 weeks with careful monitoring
If angina worsens markedly or acute coronary insufficiency develops, beta-blocker administration should be promptly reinitiated, at least temporarily (in addition to other measures appropriate for unstable angina)
Patients should be warned against interruption or discontinuance of beta-blocker therapy without physician advice
Because coronary artery disease (CAD) is common and may be unrecognized, beta-blocker therapy must be discontinued slowly, even in patients treated only for hypertension
Contraindications
Hypersensitivity
Immediate release formulation
- Hypertension and angina: Sinus bradycardia, 2°/3° heart block, cardiogenic shock, sick sinus syndrome (unless permanent pacemaker in place), severe peripheral vascular disease, pheochromocytoma
- Myocardial infarction: Severe sinus bradycardia, heart rate <45 beats/min, systolic BP <100 mmHg, significant first-degree heart block ((PR interval at least 0.24 seconds), 2°/3° heart block, moderate-to-severe cardiac failure
Extended release tablet
- Second- and third-degree heart block, deompensated heart failure, sick sinus syndrome (except in patients with functioning artificial pacemaker), severe bradycardia, cardiogenic shock
Cautions
Use with caution in cerebrovascular insufficiency, CHF, cardiomegaly, myasthenia gravis, hyperthyroidism or thyrotoxicosis (may mask signs or symptoms), liver disease, renal impairment, peripheral vascular disease, psoriasis (may cause exacerbation of psoriasis)
May exacerbate bronchospastic disease; monitor closely
Beta blockers can cause myocardial depression and may precipitate heart failure and cardiogenic shock
Sudden discontinuance can exacerbate angina and lead to MI and ventricular arrhythmias in patients with CAd
Bradycardia, including sinus pause, heart block, and cardiac arrest, has been reported; patients with 1° atrioventricular block, sinus node dysfunction, or conduction disorders may be at increased risk
Increased risk of stroke after surgery
May potentiate hypoglycemia in patients with diabetes mellitus and may mask signs and symptoms
Avoid starting high-dose regimen of extended-release metoprolol in patients undergoing noncardiac surgery; use in patients with cardiovascular risk factors is associated with bradycardia, hypotension, stroke, and death
Long-term beta blockers should not be routinely withdrawn before major surgery; however, impaired ability of the heart to respond to reflex adrenergic stimuli may augment risks of general anesthesia and surgical procedures
Metoprolol loses beta-receptor selectivity at high doses and in poor metabolizers
If drug is administered for tachycardia secondary to pheochromocytoma, it should be given in combination with an alpha blocker (which should be started before metoprolol is started)
While taking beta blockers, patients with history of severe anaphylactic reaction to variety of allergens may be more reactive to repeated challenge
Worsening cardiac failure may occur during up-titration of beta-blockers; if such symptoms occur, increase diuretics and restore clinical stability
Extended release tablet should not be withdrawn routinely prior to major surgery
Hydrochlorothiazide, can cause an idiosyncratic reaction, resulting in acute transient myopia and acute angle-closure glaucoma, which can lead to permanent vision loss if not treated; discontinue hydrochlorothiazide as rapidly as possible if symptoms occur; prompt medical or surgical treatments may need to be considered if intraocular pressure remains uncontrolled; risk factors for developing acute angle-closure glaucoma may include history of sulfonamide or penicillin allergy
Concomitant use of beta-blockers with digitalis glycosides, diltiazem, verapamil and clonidine can increase risk of bradycardia
Caution in patients with history of psychiatric illness; may cause or exacerbate CNS depression
Pregnancy and lactation
Pregnancy category: C
Lactation: Drug is concentrated in breast milk; use with caution (American Academy of Pediatrics states that drug is compatible with nursing)
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Lopressor, Toprol XL (metoprolol)
Mechanism of action
Blocks response to beta-adrenergic stimulation; cardioselective for beta1 receptors at low doses, with little or no effect on beta2 receptors
Absorption
Bioavailability: Immediate release, 40-50%; extended release, 65-77% relative to immediate release
Onset: 20 min (IV), when infused over 10 min; onset may be immediate, depending on clinical setting; 1-2 hr (PO)
Duration: 3-6 hr (PO); duration is dose-related; 24 hr (ER); 5-8 hr (IV)
Peak plasma time: Immediate release, 1.5-2 hr; extended release, 3.3 hr
Therapeutic range: 35-212 ng/mL
Distribution
Protein bound: 10%
Vd: 3.2-5.6 L/kg
Metabolism
Metabolized in liver by CYP2D6
Metabolites: Inactive
Elimination
Half-life: 3-4 hr (average); 7.5 hr (poor metabolizers); 2.8 hr (extensive metabolizers)
Excretion: Urine (95%)
Administration
IV Compatibilities
Solution: D5W, Ns
Y-site: Abciximab, alteplase, argatroban, meperidine, morphine sulfate
IV Incompatibilities
Y-site: Amphotericin B cholesteryl sulfate
Storage
Do not freeze
Store at room temperature, and protect from light
Discard solution if it is discolored or contains particles
IV Administration
Give undiluted by direct injection
