Mirtazapine, a piperazinoazepine tetracyclic antidepressant, enhances noradrenergic and serotonergic activity through blockade of central presynaptic adrenergic α<290>2<190>-receptors.

Absorption
Well absorbed from the GI tract (oral); peak plasma concentrations after 2 hours.

Distribution
Protein-binding: 85%.

Metabolism
Hepatic by demethylation and oxidation followed by glucuronidation.

Excretion
Via urine and faeces; 20-40 hours (elimination half-life).

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Increase in appetite and wt, oedema; drowsiness or sedation; dizziness, headache, increased liver enzyme levels; jaundice. Orthostatic hypotension, rash, nightmares, agitation, mania, hallucinations, paraesthesia, convulsions, tremor, myoclonus, akathisia, restless legs syndrome, arthralgia, myalgia, reversible agranulocytosis, leucopenia, granulocytopenia, hyponatraemia.

Warnings
Antidepressants increased the risk of suicidal thinking and behavior (suicidality) in short-term studies in children, adolescents, and young adults with major depressive disorder and other psychiatric disorders.

Monitor
Monitor children and adults for clinical worsening, suicidality, and unusual changes in behavior, especially during the first few months of therapy, or at times of dose changes, either increases or decreases.

Overdosage
Symptoms: Disorientation, drowsiness, impaired memory, tachycardia. Management: Ensure an adequate airway, oxygenation, and ventilation. Monitor cardiac functions. General supportive and symptomatic measures are also recommended. Do not induce emesis. Gastric lavage may be used if done soon after ingestion, or in symptomatic patients. Administer activated charcoal. No specific antidotes are known.

Epilepsy or history of seizures; avoid completely in unstable cases. Hepatic or renal impairment, cardiac disorders e.g. conduction disturbances, angina pectoris, recent MI. Hypotension, DM, psychoses, history of bipolar disorder. Stop treatment if jaundice develops. Micturition disturbances, angle-closure glaucoma, raised intraocular pressure. Monitor patient for signs of bone marrow depression. Monitor patient for suicidal tendency. Avoid abrupt withdrawal. May impair ability to drive or operate machinery. Pregnancy and lactation. Elderly.

Potentiation of sedative effects with alcohol or benzodiazepines. Increased plasma levels with potent CYP3A4 inhibitors (e.g. HIV-protease inhibitors, azole antifungals including ketoconazole, erythromycin, nefazodone). Reduced plasma levels with carbamazepine and other inducers of CYP3A4. Increased bioavailability with cimetidine.

Potentially Fatal: Do not use with or within 2 wk of stopping an MAOI; at least 1 week should elapse between discontinuing mirtazapine and initiating any drug which may provoke a serious reaction (e.g. phenelzine).

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Oral
Depression
Adult: Initially, 15 mg daily; may be increased gradually depending on clinical response. Change dose at intervals of at least 1-2 weeks. Usual effective dose: 15-45 mg daily given as single dose, preferably at bedtime, or in 2 divided doses.

May be taken with or without food

Caution when used during pregnancy

Category C: Either studies in animals have revealed adverse effects on the foetus (teratogenic or embryocidal or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the foetus.

Caution when used during lactation

Safety and efficacy not established

Use with caution

Information Not Available

Oral
Store at 15-30°C. Protect from light and moisture

Information Not Available