Mirtazapine

Oral
Major depressive disorder

Mirtazapine May be taken with or without food.

Concomitant use or within 14 days of discontinuing MAOIs.

Patient with cardiac diseases (e.g. conduction disturbances, angina pectoris, recent MI), family history of QT prolongation, low blood pressure, diabetes mellitus, acute narrow-angle glaucoma, increased intraocular pressure, micturition disturbances including prostate hypertrophy, risk factors for seizures (e.g. history of seizures, head trauma, brain damage, alcohol use disorder), history of suicidal-related events or a significant degree of suicidal ideation, history of mania or hypomania. Patients undergoing surgery. Avoid abrupt withdrawal. Renal and hepatic impairment. Elderly. Pregnancy and lactation.

Significant: Suicidal thinking and behaviour, activation of mania or hypomania, anticholinergic effects (e.g. blurred vision, constipation, xerostomia, urinary retention), bone fractures, mild pupillary dilation which may lead to narrow-angle glaucoma, jaundice, hyperkinetic movement disorders (e.g. akathisia, acute dystonia, restless leg syndrome), dyslipidaemia, orthostatic hypotension, sedation, sexual dysfunction, significant weight gain (increase of ≥7% of body weight), increased appetite, withdrawal syndrome (following abrupt discontinuation), QT prolongation, torsades de pointes, ventricular tachycardia, sudden death. Rarely, hyponatraemia.
Gastrointestinal disorders: Nausea, vomiting, diarrhoea, constipation.
General disorders and administration site conditions: Peripheral oedema, fatigue.
Musculoskeletal and connective tissue disorders: Arthralgia, myalgia, back pain.
Nervous system disorders: Headache, dizziness, somnolence, tremor.
Psychiatric disorders: Anxiety, confusion, abnormal dreams, insomnia, amnesia, lethargy.
Skin and subcutaneous tissue disorders: Exanthema.
Potentially Fatal: Severe cutaneous adverse reactions (e.g. Stevens-Johnson syndrome, toxic epidermal necrolysis, drug reaction with eosinophilia and systemic symptoms, bullous dermatitis, erythema multiforme), serotonin syndrome. Rarely, bone marrow depression (manifesting as granulocytopenia or agranulocytosis).

PO: C

This drug may impair concentration and alertness, if affected, do not drive or operate machinery.

Evaluate pregnancy status before treatment initiation. Monitor CBC, renal and hepatic function, lipid profile, and weight. Assess for signs and symptoms of serotonin syndrome; clinical worsening, unusual changes in behaviour, and suicidal behaviour or thoughts (during the 1st 1-2 months of treatment and during dose adjustments).

Symptoms: CNS depression with disorientation and prolonged sedation; tachycardia, mild hypo- or hypertension, QT prolongation, torsades de pointes. Management: Symptomatic and supportive treatment. May administer activated charcoal or employ gastric lavage. Monitor ECG.

May increase the sedating properties of benzodiazepines and other sedatives (e.g. antipsychotics, antihistamine H₁ antagonists, opioids). May enhance the anticoagulant effects of warfarin. Increased risk of QT prolongation and/or ventricular arrhythmias (e.g. torsades de pointes) with QT interval prolonging drugs. Decreased plasma concentration with carbamazepine and phenytoin.
Potentially Fatal: Increased risk of serotonin syndrome when used concurrently with or within 14 days of discontinuing MAOIs (e.g. isocarboxazid, IV methylthioninium chloride, phenelzine, tranylcypromine) and serotonergic agents (e.g. SSRIs, lithium, tramadol, venlafaxine, triptans).

May increase the CNS depressant effect of alcohol. Increased risk of serotonin syndrome with St. John's wort.

Description:
Mechanism of Action: Mirtazapine is a tetracyclic antidepressant. It acts by blocking central presynaptic α₂-adrenergic receptors, leading to increased release of norepinephrine and serotonin. It is also a potent antagonist of 5-HT₂ and 5-HT₃ serotonin receptors and H₁ histamine receptors. In addition, it exhibits moderate antagonistic activity at peripheral α₁-adrenergic and muscarinic receptors.
Onset: Depression: Within 1-2 weeks.
Pharmacokinetics:
Absorption: Rapidly and completely absorbed from the gastrointestinal tract. Bioavailability: Approx 50%. Time to peak plasma concentration: Approx 2 hours.
Distribution: Crosses the placenta and enters breast milk. Plasma protein binding: Approx 85%.
Metabolism: Extensively metabolised in the liver via demethylation and hydroxylation followed by glucuronidation by CYP1A2 and CYP2D6 into 8-hydroxy metabolite and by CYP3A4 into N-desmethyl (pharmacologically active) and N-oxide metabolite.
Excretion: Via urine (75%); faeces (15% as metabolites). Elimination half-life: Approx 20-40 hours.

Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 4205, Mirtazapine. https://pubchem.ncbi.nlm.nih.gov/compound/Mirtazapine. Accessed Aug. 26, 2025.

Store below 30°C. Protect from light and moisture.

Antidepressants

N06AX11 - mirtazapine ; Belongs to the class of other antidepressants.

Aurozapine Tablets 15 mg and 30 mg (Healol Pharmaceuticals Sdn. Bhd.). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my. Accessed 09/07/2025.

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Mirtazapine Tablet, Film Coated (NorthStar Rx LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 09/07/2025.

Mirtazapine Tablet, Orally Disintegrating (Viona Pharmaceuticals Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 09/07/2025.

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Mirtazapine. UpToDate Lexidrug, Lexi-Drugs Multinational Online. Waltham, MA. UpToDate, Inc. https://online.lexi.com. Accessed 09/07/2025.

Remeron SolTab 15 mg and 30 mg Orodispersible Tablets (Organon Malaysia Sdn. Bhd.). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my. Accessed 09/07/2025.