What is Metoprolol?
A prescription beta-blocker used for hypertension, angina, and heart failure. It comes as tablets, extended-release tablets, and an oral solution.
Generic Name
- metoprolol tartrate (Lopressor)
- metoprolol succinate (Toprol-XL)
Brand Names
Lopresor, Lopresor SR, Lopressor, Toprol-XL, Betaloc, Kapspargo Sprinkle, Beloc, Seloken.
Drug Classification of Metoprolol
Therapeutic: antianginals, antihypertensives.
Pharmacologic: beta-blockers.
Indications and Therapeutic Effects
Metoprolol treats hypertension (by reducing cardiac workload and relaxing the vessels), angina pectoris (chest pain from reduced coronary flow, treated by lowering workload and improving flow), heart failure (same mechanism), and atrial fibrillation (slowing the rate and reducing clot risk). It is also given for myocardial infarction prevention in patients with a history of heart disease.
Unlabeled uses include supraventricular tachycardia, migraine prophylaxis (blunting the adrenaline response that triggers migraines), moderate to severe tremors, aggressive behavior as part of a broader plan, and anxiety.
Mechanism of Action
Adrenaline and noradrenaline from the adrenal glands bind cardiac beta receptors and drive up heart rate and blood pressure. Metoprolol blocks those receptors, so the hormones can't bind. The result is a slower rate, lower workload, and lower blood pressure.
Precautions and Contraindications
Screen for allergy or prior reaction to metoprolol. Use caution in heart conditions where slowing the rate is dangerous, such as uncompensated heart failure or existing bradycardia, and in patients who drop their pressure on standing. Metoprolol is generally contraindicated in cardiogenic shock, where its negative chronotropic and inotropic effects further cut cardiac output and tissue perfusion.
Do not use in bradycardia, heart block, or sick sinus syndrome, all of which a rate-slowing drug can worsen. Bradycardia is a too-slow rate that causes fatigue, dizziness, and fainting. Heart block is disrupted conduction of the signals that regulate the beat. Sick sinus syndrome is failure of the sinus node, the heart's natural pacemaker, producing slow or irregular beats. Use metoprolol cautiously in kidney or liver disease, since it can affect organ function. Older references list metoprolol as pregnancy category C, but the FDA retired the letter categories under the 2015 Pregnancy and Lactation Labeling Rule; current labels describe the actual risk in narrative form instead. The drug crosses the placenta and passes into breast milk, so weigh the risks and benefits with the prescriber in pregnant or breastfeeding patients.
Drug Interactions
Drug-Drug
Inform the physician and team of every medication, supplement, and herbal product the patient takes so interactions can be caught and the plan adjusted.
Calcium channel blockers such as verapamil and diltiazem add to the hypotension and bradycardia risk. Blood thinners such as warfarin and heparin raise bleeding and bruising risk. Alcohol increases dizziness and drowsiness, so limit or avoid it. Sympathomimetics (amphetamines, cocaine, ephedrine, epinephrine, norepinephrine, phenylephrine, pseudoephedrine) can produce unopposed alpha-adrenergic stimulation (excessive hypertension, bradycardia). Concurrent thyroid administration may decrease metoprolol's effectiveness. Metoprolol may alter the effectiveness of insulins or oral hypoglycemic agents (dose adjustment may be needed) and may decrease the effectiveness of theophylline. It may decrease the beneficial beta1-cardiovascular effects of dopamine or dobutamine. Use cautiously within 14 days of MAO inhibitor therapy (may cause hypertension).
Adverse Effects
Common side effects: fatigue, dizziness, headache, constipation, diarrhea, dry mouth, flatulence, gastric pain, heartburn, increased liver enzymes, nausea, and vomiting; these usually resolve after a few days. Serious effects (rare): hyperglycemia, hypoglycemia, slow or irregular heartbeat, worsening chest pain, bronchospasm, wheezing, and difficulty breathing. Allergic reactions are rare but can be serious (itching, rash, hives, difficulty breathing). Others: erectile dysfunction, decreased libido, urinary frequency, drug-induced hepatitis, and drug-induced lupus syndrome.
Administration Considerations
Available Forms
- Tablets (tartrate): 25 mg, 50 mg, 100 mg.
- Extended-release tablets (succinate; Toprol XL): 25 mg, 50 mg, 100 mg, 200 mg.
- Solution for injection: 1 mg/mL.
- In combination with: hydrochlorothiazide (Dutoprol, Lopressor HCT).
Dosage for Adults
- PO (Adults):
- Antihypertensive/antianginal. 25-100 mg/day as a single dose initially or 2 divided doses; may be increased q 7 days as needed up to 450 mg/day (immediate-release) or 400 mg/day (extended-release) (for angina, give in divided doses). Extended-release products are given once daily.
- MI. 25-50 mg (starting 15 min after last IV dose) q 6 hr for 48 hr, then 100 mg twice daily.
- Heart failure. 12.5-25 mg once daily (of extended-release), can be doubled every 2 wk up to 200 mg/day.
- Migraine prevention. 50-100 mg 2-4 times daily (unlabeled).
- IV (Adults):
- MI. 5 mg q 2 min for 3 doses, followed by oral dosing.
Pharmacokinetics
Metoprolol is absorbed from the GI tract (rate affected by food and individual metabolism), distributed throughout the body to target tissues such as the heart, metabolized by the liver, and excreted in the urine, with both metabolism and excretion influenced by hepatic and renal function. Half-life is 3-7 hr.
Nursing Considerations for Metoprolol
Nursing Assessment
Monitor blood pressure, ECG, and pulse frequently during dose adjustment and periodically during therapy. Assess for hypersensitivity to metoprolol before giving it. During and for several hours after parenteral administration, monitor vital signs and ECG every 5-15 minutes; if the heart rate is <40 bpm, especially with decreased cardiac output, give atropine 0.25-0.5 mg IV. Watch for side effects (fatigue, dizziness, headache, diarrhea) and notify the provider promptly. Monitor intake and output ratios and daily weights, and assess routinely for signs and symptoms of heart failure (dyspnea, rales/crackles, weight gain, peripheral edema, jugular venous distention). Assess the frequency and characteristics of anginal attacks periodically.
Monitor labs: metoprolol may increase BUN, serum lipoprotein, potassium, triglyceride, and uric acid, and may increase ANA titers, blood glucose, serum alkaline phosphatase, LDH, AST, and ALT.
Nursing Diagnosis
- Risk for decreased cardiac tissue perfusion from reduced rate and contractility cutting cardiac output and tissue oxygen delivery.
- Impaired gas exchange related to bronchoconstriction, which narrows the airways and causes shortness of breath, wheezing, or coughing.
- Decreased cardiac output related to negative inotropic effect.
- Risk for injury from dizziness or hypotension and resulting falls.
- Impaired physical mobility related to fatigue.
- Risk for impaired skin integrity from decreased peripheral circulation and pressure ulcers.
- Deficient knowledge regarding the medication regimen and potential side effects.
Metoprolol Nursing Interventions
Confirm the patient is taking the drug at the correct dose and frequency, and report discrepancies. Before IV administration, have a second practitioner independently check the original order and dose calculations. Check the label: do not confuse Toprol-XL (metoprolol) with Topamax (topiramate), Lopressor with Lyrica, or metoprolol tartrate with metoprolol succinate. Encourage moderate physical activity as tolerated. Take the apical pulse before each dose; if <50 bpm or an arrhythmia occurs, withhold the dose and notify the provider. Give with meals or directly after eating to cut GI effects. Provide written medication materials. Extended-release metoprolol must be swallowed whole, not broken, crushed, or chewed, since that releases the drug too fast.
Intravenous Administration:
- IV Push:
- Diluent: Administer undiluted.
- Concentration: 1 mg/mL.
- Rate: Administer over 1 min.
- Y-Site Compatibility: acyclovir, alemtuzumab, alfentanil, alteplase, amikacin, aminocaproic acid, aminophylline, amiodarone, amphotericin B liposome, anidulafungin, argatroban, ascorbic acid, atropine, aztreonam, benztropine, bivalirudin, bleomycin, bumetanide, buprenorphine, butorphanol, calcium chloride, calcium gluconate, cangrelor, carboplatin, carmustine, caspofungin, cefazolin, cefonicid, cefotaxime, cefotetan, cefoxitin, ceftaroline, ceftazidime, ceftriaxone, cefuroxime, chloramphenicol, chlorpromazine, cisplatin, clindamycin, cyanocobalamin, cyclophosphamide, cyclosporine, cytarabine, dactinomycin, daptomycin, dexamethasone, dexmedetomidine, digoxin, diltiazem, diphenhydramine, dobutamine, docetaxel, dopamine, doxorubicin hydrochloride, doxycycline, enalaprilat, ephedrine, epinephrine, epirubicin, epoetin alfa, eptifibatide, esmolol, etoposide, etoposide phosphate, famotidine, fenoldopam, fentanyl, fluconazole, fludarabine, fluorouracil, folic acid, foscarnet, fosphenytoin, furosemide, ganciclovir, gemcitabine, gentamicin, glycopyrrolate, granisetron, heparin, hetastarch, hydrocortisone, hydromorphone, idarubicin, ifosfamide, imipenem/cilastatin, indomethacin, insulin, irinotecan, isoproterenol, ketorolac, labetalol, leucovorin, linezolid, lorazepam, magnesium sulfate, mannitol, mechlorethamine, meperidine, methotrexate, methyldopate, methylprednisolone, metoclopramide, metronidazole, midazolam, milrinone, mitoxantrone, morphine, multivitamins, mycophenolate, nafcillin, nalbuphine, naloxone, nitroprusside, norepinephrine, octreotide, ondansetron, oxacillin, oxaliplatin, oxytocin, paclitaxel, palonosetron, pamidronate, pancuronium, papaverine, pemetrexed, penicillin G, pentamidine, pentazocine, pentobarbital, phenobarbital, phenylephrine, phytonadione, piperacillin/tazobactam, potassium acetate, potassium chloride, procainamide, prochlorperazine, promethazine, propranolol, protamine, pyridoxine, quinupristin/dalfopristin, ranitidine, rocuronium, sodium bicarbonate, streptokinase, succinylcholine, sufentanil, tacrolimus, teniposide, theophylline, thiamine, thiotepa, tigecycline, tirofiban, tobramycin, vancomycin, vasopressin, vecuronium, verapamil, vincristine, vinorelbine, voriconazole, zoledronic acid.
- Y-Site Incompatibility: allopurinol, amphotericin B colloidal, amphotericin B lipid complex, dantrolene, diazepam, pantoprazole, phenytoin, trimethoprim/sulfamethoxazole.
Patient Education and Teaching
Explain what metoprolol is for and why it was prescribed. Teach the correct dose and frequency, and whether to take it with or after meals. Review the common side effects (fatigue, dizziness, shortness of breath) and how to manage them, and tell the patient to report any adverse reactions or symptom changes, including new shortness of breath or depression. Stress monitoring blood pressure, heart rate, and respiratory rate and reporting significant changes.
Take the drug as directed, at the same time each day, even when feeling well. Do not skip or double doses; take a missed dose as soon as possible up to 8 hr before the next dose. Abrupt withdrawal may precipitate life-threatening arrhythmias, hypertension, or myocardial ischemia, so the drug is tapered gradually, usually over 1 to 2 weeks, rather than stopped suddenly (StatPearls). Teach the patient and family to check pulse daily and blood pressure biweekly and to report significant changes. Avoid driving or other activities that require alertness until the drug's effect is known, since it may cause drowsiness. Change positions slowly to minimize orthostatic hypotension. Warn that the drug may increase sensitivity to cold, and to report that if it occurs.
Discuss possible drug interactions, including over-the-counter drugs, supplements, and herbals, and the need to report any medication changes. Stress compliance and not stopping the drug without consulting the provider. Teach proper storage (safe, secure, out of reach of children, away from heat and moisture) and the value of followup checkups. In diabetic patients, monitor blood glucose, especially if weakness, malaise, irritability, or fatigue occurs, since metoprolol can affect blood sugar. Have the patient inform any provider of the regimen before treatment or surgery, since the drug may need adjustment before procedures, and carry identification describing the disease process and regimen at all times for emergencies. Reinforce that medication controls but does not cure hypertension, so continue weight loss, sodium restriction, stress reduction, regular exercise, moderation of alcohol, and smoking cessation.
Evaluation and Desired Outcomes
Desired outcomes depend on the condition treated: lowered blood pressure, improved heart function and reduced symptoms in heart failure or angina, improved blood flow, a slower rate that prevents palpitations and shortness of breath in atrial fibrillation, relief of anginal chest pain, reduced anxiety symptoms, decreased tremors, and lower clot risk from the slowed rate.
Frequently Asked Questions
When do you hold a dose of metoprolol? Take an apical pulse for a full minute before each dose. If the rate is below 50 bpm or an arrhythmia is present, withhold the dose and notify the provider (StatPearls).
Why can't patients stop metoprolol suddenly? Abrupt withdrawal can trigger rebound hypertension, life-threatening arrhythmias, or myocardial ischemia. The drug is tapered gradually, usually over 1 to 2 weeks, rather than stopped at once (StatPearls).
What is the difference between metoprolol tartrate and succinate? Tartrate (Lopressor) is immediate-release and dosed in divided doses; succinate (Toprol-XL) is extended-release and given once daily. They are not interchangeable milligram for milligram, and the extended-release form must be swallowed whole, never crushed or chewed.
Is metoprolol still pregnancy category C? That older label is outdated. The FDA retired the A/B/C/D/X letter categories under the 2015 Pregnancy and Lactation Labeling Rule, so current labels describe the actual risk in narrative form. Metoprolol crosses the placenta and enters breast milk, so use is individualized with the prescriber.
What should diabetic patients know about metoprolol? Beta-blockers can blunt the usual warning signs of low blood sugar, such as a racing heartbeat, leaving sweating as the main clue. Diabetic patients should monitor glucose more closely, especially if they feel weak, irritable, or unusually tired.
Can metoprolol be used in asthma or COPD? Use caution. Even though metoprolol is beta-1 selective, at higher doses it can cause bronchospasm and wheezing, so patients with reactive airway disease are monitored for breathing changes and told to report new shortness of breath.