Home Drug Guide Mirtazapine

Drug Guide

Generic Name

Mirtazapine

Brand Names Remeron, Remeron Soltab

Classification

Therapeutic: Antidepressant

Pharmacological: Alpha-2 adrenergic antagonist, Noradrenergic and specific serotonergic antidepressant (NaSSA)

FDA Approved Indications

  • Major depressive disorder (MDD)

Mechanism of Action

Mirtazapine works by antagonizing central presynaptic alpha-2 adrenergic receptors, which increases the release of norepinephrine and serotonin. It also antagonizes specific serotonin receptors (5-HT2 and 5-HT3) and histamine H1 receptors, contributing to its antidepressant effects and sedative properties.

Dosage and Administration

Adult: Initially 15 mg at bedtime, titrated up to 30-45 mg daily based on response and tolerability.

Pediatric: Not approved for pediatric use.

Geriatric: Start at lower doses due to increased sensitivity, usually 15 mg at bedtime.

Renal Impairment: Use caution; no specific dosage adjustment established, monitor closely.

Hepatic Impairment: Use caution; start at lower doses, monitor liver function.

Pharmacokinetics

Absorption: Well absorbed orally, food has minor effect on absorption.

Distribution: Widely distributed; approximately 85% protein-bound.

Metabolism: Extensively metabolized in the liver primarily via CYP2D6, CYP1A2, and CYP3A4 pathways.

Excretion: Metabolites excreted in urine and feces.

Half Life: Approximately 20-40 hours.

Contraindications

  • Hypersensitivity to mirtazapine

Precautions

  • Use cautiously in patients with a history of seizure disorders, bipolar disorder (risk of mania), or angle-closure glaucoma. Monitor for signs of depression or worsening mood, especially early in therapy. Use with caution in hepatic impairment.

Adverse Reactions - Common

  • Drowsiness or sedation (Common)
  • Increase in appetite, weight gain (Common)
  • Dizziness (Common)
  • Dry mouth (Common)

Adverse Reactions - Serious

  • Suicidal thoughts or behaviors (Serious, especially in young adults and adolescents)
  • Blood dyscrasias, agranulocytosis (rare) (Rare)
  • Serotonergic syndrome (when combined with other serotonergic agents) (Rare)

Drug-Drug Interactions

  • MAO inhibitors (risk of serotonin syndrome), other CNS depressants, serotonergic drugs, CYP450 inhibitors or inducers

Drug-Food Interactions

  • Alcohol may increase sedative effects.

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Monitor mood, suicidal ideation, and mental status. Assess weight and appetite. Check for allergic reactions and adverse effects.

Diagnoses:

  • Risk for injury related to sedation or dizziness
  • Imbalanced nutrition: less than body requirements related to nausea or decreased appetite

Implementation: Administer at bedtime to reduce daytime sedation. Monitor for therapeutic effects and adverse reactions. Educate patient about the onset of action (may take 1-4 weeks).

Evaluation: Assess improvement in depressive symptoms and monitor for adverse effects.

Patient/Family Teaching

  • Instruct patient to take medication as prescribed, usually at bedtime.
  • Warn about drowsiness and advise caution when driving or operating machinery.
  • Advise to avoid alcohol and sedatives. Discuss potential weight gain and appetite changes.
  • Report mood changes, suicidal thoughts, or adverse effects immediately.

Special Considerations

Black Box Warnings:

  • Suicidality in young adults, especially during initial treatment

Genetic Factors: CYP2D6 poor metabolizers may have increased plasma levels.

Lab Test Interference: None established.

Overdose Management

Signs/Symptoms: Drowsiness, tachycardia, agitation, hallucinations, seizures, coma.

Treatment: Supportive care, gastric lavage if ingestion is recent, activated charcoal, and symptomatic treatment. Monitor cardiac status for arrhythmias.

Storage and Handling

Storage: Store at room temperature, 20-25°C (68-77°F), away from moisture and light.

Stability: Stable under recommended storage conditions for the duration of its shelf life.

🛡️ 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.