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MIRTAZAPINE

Medical Diagnosis and Drugs, Medications
MIRTAZAPINE
(mir-taz'a-peen)
Remeron, Remeron SolTab
Classifications: psychotherapeutic agent; antidepressant, tetracyclic; anxiolytic agent;
Therapeutic: antidepressant, tetracyclic; antianxiety
Pregnancy Category: C

Availability

15 mg, 30 mg, 45 mg tablets and orally disintegrating tablets

Action

Tetracyclic antidepressant pharmacologically and therapeutically similar to tricyclic antidepressants. Tetracyclics enhance central nonadrenergic and serotonergic activity; thought to be due to normalizing of neurotransmission efficacy. Mirtazapine is a potent antagonist of 5-HT2 and 5-HT3 serotonin receptors.

Therapeutic Effect

Acts as antidepressant. Effectiveness is indicated by mood elevation.

Uses

Treatment of depression.

Contraindications

Hypersensitivity to mirtazapine or mianserin; hypersensitivity to other antidepressants (e.g., tricyclic antidepressants and MAOI depressants), acute MI; fever, infection; agranulocytosis, neutropenia, hematologic disease; suicidal ideation; jaundice, ethanol intoxication; pregnancy (category C), lactation.

Cautious Use

History of cardiovascular or GI disorders; BPH, urinary retention; narrow-angle glaucoma, increased intraocular pressure; hepatic or renal impairment, renal failure; hypercholesterolemia, hypertriglyceridemia, thrombocytopenia; older adults; angina, cardiac arrhythmias, anticholinergic medications; bipolar disorder, mania, bone marrow suppression, PKU, history of MI; cerebrovascular disease, seizure disorder, seizures, stroke; depression; hypovolemia, surgery; closed-angle glaucoma; ileus, GI obstruction, dehydration; diabetes mellitus, diabetic ketoacidosis. Safety and effectiveness in children are not established.

Route & Dosage

Depression
Adult: PO 15 mg/d in single dose h.s., may increase q1–2wk (max: 45 mg/d)
Geriatric: PO Use lower doses

Renal or Hepatic Impairment
Use lower doses.

Administration

Oral
  • Give preferably prior to sleep to minimize injury potential.
  • Begin drug no sooner than 14 d after discontinuation of an MAO inhibitor.
  • Reduce dosage as warranted with severe renal or hepatic impairment and in older adults.
  • Store at 20°–25° C (68°–77° F) in tight, light-resistant container.

Adverse Effects (≥1%)

Body as a Whole: Asthenia, flu syndrome, back pain, general and peripheral edema, malaise. CNS: Somnolence, dizziness, abnormal dreams, abnormal thinking, tremor, confusion, depression, agitation, vertigo, twitching. CV: Hypertension, vasodilation. GI: Nausea, vomiting, abdominal pain, increased appetite/weight gain, dry mouth, constipation, anorexia, cholecystitis, stomatitis, colitis, abnormal liver function tests. Respiratory: Dyspnea, cough, sinusitis. Skin: Pruritus, rash. Urogenital: Urinary frequency.

Interactions

Drug: Additive cognitive and motor impairment with alcohol or benzodiazepines; increase risk of hypertensive crisis with maois. Herbal: Kava, valerian may potentiate sedative effects.

Pharmacokinetics

Absorption: Rapidly absorbed from GI tract, 50% reaches systemic circulation. Peak: 2 h. Distribution: 85% protein bound. Metabolism: In liver by cytochrome P450 system (CYP2D6, CYP1A2, CYP3A). Elimination: 75% in urine, 15% in feces. Half-Life: 20–40 h.

Nursing Implications

Assessment & Drug Effects

  • Lab tests: Monitor WBC count with differential, lipid profile, and ALT/AST periodically.
  • Patients should be monitored for worsening of depression or emergence of suicidality.
  • Assess for weight gain and excessive somnolence or dizziness.
  • Monitor for orthostatic hypotension with a history of cardiovascular or cerebrovascular disease. Periodically monitor ECG especially in those with known cardiovascular disease.
  • Monitor those with a history of increased intraocular pressure or urinary retention carefully for worsening or recurrence.
  • Monitor those with history of seizures for lowering of the seizure threshold.

Patient & Family Education

  • Do not drive or engage in potentially hazardous activities until response to drug is known.
  • Do not use alcohol while taking drug.
  • Report immediately unexplained fever or S&S of infection, especially flu-like symptoms, to physician.
  • Do not take other prescription or OTC drugs without consulting physician.
  • Make position changes slowly especially from lying or sitting to standing. Report dizziness, palpitations, and fainting.
  • Notify (women) physician immediately if you become pregnant.
  • Monitor weight periodically and report significant weight gains.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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