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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