Home Drug Guide Metoprolol Fumarate

Drug Guide

Generic Name

Metoprolol Fumarate

Brand Names Lopressor

Classification

Therapeutic: Cardiovascular agent, Beta-blocker

Pharmacological: Beta-adrenergic antagonist

FDA Approved Indications

  • Hypertension
  • Angina pectoris
  • Below-the-knee ischemia (off-label use in some cases)
  • Myocardial infarction (post-MI) prophylaxis

Mechanism of Action

Metoprolol selectively blocks beta-1 adrenergic receptors in the heart, reducing heart rate, myocardial contractility, and cardiac output, which lowers blood pressure and oxygen demand.

Dosage and Administration

Adult: Initially 25-50 mg once daily; may be titrated up to 200 mg/day in divided doses based on response.

Pediatric: Not typically recommended for children; dose determined on a case-by-case basis under specialist supervision.

Geriatric: Start at lower doses due to increased sensitivity and potential for adverse effects; gradual titration advised.

Renal Impairment: Use with caution; monitor renal function and adjust dose if necessary.

Hepatic Impairment: Use with caution; no specific dose adjustment, but liver function should be considered.

Pharmacokinetics

Absorption: Well absorbed with oral bioavailability of approximately 50% due to first-pass metabolism.

Distribution: Widely distributed, approximately 12% bound to plasma proteins.

Metabolism: Extensively metabolized in the liver via cytochrome P450 enzymes (mainly CYP2D6).

Excretion: Excreted primarily in urine as metabolites; small amount unchanged.

Half Life: 3 to 7 hours, slightly longer in elderly or certain patient populations.

Contraindications

  • Severe bradycardia
  • Heart block greater than first degree without pacemaker
  • Decompensated heart failure
  • Hypotension

Precautions

  • Use with caution in patients with asthma or airway obstruction, diabetes (may mask hypoglycemia symptoms), peripheral vascular disease, or Raynaud's phenomenon.

Adverse Reactions - Common

  • Fatigue (Common)
  • Dizziness (Common)
  • Bradycardia (Common)
  • Gastrointestinal discomfort (Common)

Adverse Reactions - Serious

  • Severe Bradycardia or Heart Block (Rare)
  • Hypotension (Rare)
  • Bronchospasm in susceptible individuals (Rare)
  • Masking of hypoglycemia symptoms (Rare)

Drug-Drug Interactions

  • Other antihypertensives, especially calcium channel blockers like verapamil or diltiazem
  • Amiodarone
  • Digoxin
  • NSAIDs (may reduce antihypertensive effect)

Drug-Food Interactions

  • Alcohol (may enhance hypotensive effects)

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Monitor BP, HR prior to and during therapy; assess for signs of heart failure or worsening cardiac symptoms.

Diagnoses:

  • Risk for decreased cardiac output
  • Ineffective tissue perfusion

Implementation: Administer doses as prescribed; monitor vital signs regularly; educate patient on recognizing adverse effects.

Evaluation: Maintain target blood pressure; observe for adverse reactions; adjust dosage if necessary.

Patient/Family Teaching

  • Take medication exactly as prescribed.
  • Notify healthcare provider if experiencing symptoms like dizziness, slow heartbeat, or signs of heart failure.
  • Do not abruptly stop medication without consulting healthcare provider.
  • Avoid alcohol and consult with provider before using other medications or supplements.

Special Considerations

Black Box Warnings:

  • Potential to cause or exacerbate heart failure; abrupt discontinuation may cause acute tachycardia, hypertension, or ischemia.

Genetic Factors: Metabolism may vary with CYP2D6 polymorphisms affecting drug levels.

Lab Test Interference: May mask hypoglycemia symptoms in diabetic patients.

Overdose Management

Signs/Symptoms: Bradycardia, hypotension, bronchospasm, hypoglycemia, or cardiac arrest.

Treatment: Discontinue medication, administer activated charcoal if ingestion was recent, support vital signs, and administer Atropine for bradycardia, vasopressors for hypotension, or intravenous fluids as needed.

Storage and Handling

Storage: Store at room temperature, away from light and moisture.

Stability: Stable under recommended conditions; check expiration date regularly.

🛡️ 5 Critical Medication Safety Tips for Nurses

1

Triple-Check High-Risk Medications

Always have another nurse verify insulin, heparin, warfarin, and chemotherapy drugs. These "high-alert" medications cause the most serious errors. Check concentration, dose calculation, and pump settings twice.

2

Know Look-Alike, Sound-Alike Drugs

Common mix-ups: hydromorphone/morphine, Celebrex/Celexa, Zyprexa/Zyrtec. Always use BOTH generic and brand names, read labels twice, and use barcode scanning when available. One wrong letter can be fatal.

3

Assess Before AND After Giving Meds

Check vitals before cardiac meds, pain levels before analgesics, and blood glucose before insulin. Always reassess within 30 minutes to evaluate effectiveness and watch for adverse reactions.

4

Watch for Drug Interactions

Common dangerous combinations: warfarin + aspirin (bleeding), ACE inhibitors + potassium (hyperkalemia), digoxin + diuretics (toxicity). Always check drug interactions before administering new medications.

5

Educate Your Patients

Teach patients medication names, purposes, major side effects, and what to report. Informed patients catch errors and improve compliance. Always encourage questions - an educated patient is a safer patient.

⚡ Remember: When in doubt, don't give it out! It's always safer to double-check than regret later.

⚠️ Medical Disclaimer

This drug guide is for educational purposes only and is NOT intended for clinical use. Always consult current prescribing information, healthcare providers, and institutional protocols before administering any medication. Do not use this information for patient care decisions.