Mirtazapine


Concise Prescribing Info
Indications/Uses
Major depressive disorder.
Dosage/Direction for Use
Adult : PO Initial: 15 mg once daily at bedtime; may adjust gradually up to 45 mg/day at intervals at least than 1-2 weeks depending on patient’s clinical response and tolerability.
Dosage Details
Oral
Major depressive disorder
Adult: Initially, 15 mg once daily at bedtime; may adjust gradually up to 45 mg daily at intervals of at least 1-2 weeks depending on the patient’s clinical response and tolerability.
Administration
May be taken with or without food.
Contraindications
Concomitant or within 14 days of discontinuing MAOIs including linezolid and IV methylene blue.
Special Precautions
Patient with suicidal ideation, bipolar disorder, known or history of seizure disorder, benign prostatic hyperplasia, paralytic ileus, urinary retention, visual disturbances, volume depletion, diabetes mellitus, CV or cerebrovascular disease, risk factors for QT prolongation, hypotension, angle-closure glaucoma, increased intraocular pressure. Dehydrated patients. Renal and hepatic impairment. Pregnancy and lactation.
Adverse Reactions
Significant: Akathisia, anticholinergic effects (e.g. blurred vision, constipation, xerostomia), arrhythmia, agranulocytosis, hyperlipidaemia, hyponatraemia, increased sedation, increased risk of suicidal ideation, angle-closure glaucoma, orthostatic hypotension, increased transaminase levels, increased appetite, weight gain.
Blood and lymphatic system disorders: Anaemia, leucopenia, lymphocytosis, pancytopenia and thrombocytopenia.
Cardiac disorders: Angina pectoris, bradycardia, myocardial infarction.
Ear and labyrinth disorders: Deafness, hyperacusis, otitis media.
Endocrine disorders: Goitre, hyperprolactinaemia.
Eye disorders: Abnormal accommodation, abnormal lacrimation, conjunctivitis, diplopia, blepharitis, eye pain.
Gastrointestinal disorders: Abdominal pain, acute abdominal syndrome, colitis, constipation, diarrhoea, dry mouth, abdomen enlarged, eructation, gastritis, glossitis, hiccup, intestinal obstruction, pancreatitis, salivary gland enlargement, stomatitis, tongue discolouration, nausea, vomiting, ulcer.
General disorders and administration site conditions: Abnormal healing, asthenia, ataxia, fatigue, fever, malaise, oedema.
Hepatobiliary disorders: Cholecystitis, jaundice, liver cirrhosis.
Injury, poisoning and procedural complications: Asphyxia, bone fracture, phlebitis, tendon rupture.
Investigations: Increased acid phosphatase, increased creatine kinase.
Metabolism and nutrition disorders: Anorexia, frequent thirst, dehydration, peripheral oedema.
Musculoskeletal and connective tissue disorders: Arthralgia, arthritis, back pain, bursitis, gout, hypotonia, myalgia, myositis, neck rigidity, rhabdomyolysis, tenosynovitis.
Nervous system disorders: Agitation, amnesia, cerebral ischaemia, convulsions, dizziness, dyskinesia, dystonia, extrapyramidal syndrome, headache, hypokinesia, hypoesthesia, nystagmus, myasthenia, myoclonus, migraine, paralysis, paraesthesia, restless legs syndrome, stupor, tremors, vertigo.
Psychiatric disorders: Anxiety, apathy, aphasia, confusion, delirium, delusions, dementia, depersonalization, depression, dysarthria, emotional lability, euphoria, hallucination, hostility, insomnia, manic reaction, neurosis, paranoid reaction, somnolence, abnormal dreams or thinking.
Renal and urinary disorders: Cystitis, dysuria, polyuria, urinary frequency, urinary retention, UTI.
Reproductive system and breast disorders: Breast engorgement and enlargement, amenorrhoea, dysmenorrhoea, haematuria, increased libido, leucorrhoea, metrorrhagia, impotence.
Respiratory, thoracic and mediastinal disorders: Cough, dyspnoea, bronchitis, asthma, laryngitis, flu syndrome, pneumonia, pneumothorax, pulmonary embolus, sinusitis.
Skin and subcutaneous tissue disorders: Acne, alopecia, exanthema, erythema multiforme, exfoliative dermatitis, urticaria, herpes simplex, herpes zoster, petechiae, rash, seborrhoea, skin hypertrophy, skin photosensitivity.
Vascular disorders: Epistaxis, hypertension, hypotension, syncope, vasodilation.
Potentially Fatal: Serotonin syndrome, severe skin reactions (e.g. Stevens-Johnson syndrome, toxic epidermal necrolysis).
Patient Counseling Information
This drug may cause somnolence, if affected, do not drive or operate machinery.
MonitoringParameters
Screen for personal or family history of bipolar disorder prior to initiation of therapy. Monitor for suicidal thoughts during early antidepressant therapy and period of dosage adjustment; signs of altered mental status (e.g. depression, anxiety, mania, panic attacks), signs of agranulocytosis (e.g. sore throat, fever, stomatitis), signs of serotonin syndrome, eyes, renal, hepatic and cardiac function. Monitor blood pressure, serum electrolytes, lipid profile, blood sugar and CBC.
Overdosage
Symptoms: Disorientation, prolonged sedation, impaired memory, tachycardia and mild hypertension or hypotension. Management: Symptomatic treatment. May perform gastric lavage and administer activated charcoal.
Drug Interactions
Increased sedative effects with benzodiazepines (e.g. alprazolam, clonazepam, diazepam). Increased risk of serotonin syndrome with SSRIs (e.g. escitalopram, fluoxetine, sertraline), serotonin-norepinephrine reuptake inhibitors (e.g. venlafaxine, duloxetine, sibutramine), TCAs (e.g. amitriptyline, clomipramine, imipramine), triptans (e.g. sumatriptan, zolmitriptan, almotriptan), amphetamine, buspirone, fentanyl, lithium, tramadol and tryptophan. Increased serum plasma concentration with potent CYP3A4 inhibitors such as HIV-protease inhibitors (e.g. ritonavir), azole antifungals (e.g. itraconazole, ketoconazole), erythromycin and nefazodone. Decreased serum plasma concentration with potent CYP3A4 inducers (e.g. carbamazepine, phenytoin, rifampin). Increased serum plasma concentration when concurrently administered with cimetidine. Increased risk of QT prolongation with drugs when concurrently administered with QTc interval prolonging drugs (e.g. azithromycin, fluconazole, chloroquine). May diminish the antihypertensive effect of α2-agonist (e.g. clonidine, methyldopa). May enhance the anticoagulant effect of warfarin.
Potentially Fatal: Increased risk of serotonin syndrome when concurrently administered with or within 14 days of discontinuing MAOIs (e.g. isocarboxazid, linezolid, IV methylene blue, phenelzine, selegiline, tranylcypromine).
Food Interaction
Increased sedative effect with alcohol. Increased risk of serotonin syndrome with St. John’s wort.
Action
Description: Mirtazapine, a tetracyclic antidepressant, blocks the central presynaptic α2- adrenergic autoreceptors and heteroceptors resulting in an increased noradrenergic and serotonergic activity. It also has a potent blocking activity in 5-HT2, 5-HT3 serotonin receptor and H1 histamine receptor while a moderate blocking activity in peripheral α1-adrenergic and muscarinic antagonist.
Pharmacokinetics:
Absorption: Rapidly and well 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 oxidation then glucuronidation by CYP2D6 and CYP1A2 into 8-hydroxy metabolite while by CYP3A4 into N-desmethyl (pharmacologically active) and N-oxide metabolite.
Excretion: Mainly via urine (75%); faeces (15%). Elimination half-life: Approx 20-40 hours.
Chemical Structure

Chemical Structure Image
Mirtazapine

Storage
Store between 20-25°C. Protect from light and moisture.
MIMS Class
ATC Classification
N06AX11 - mirtazapine ; Belongs to the class of other antidepressants.
References
Anon. Mirtazapine. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 15/09/2020.

Anon. Mirtazapine. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 15/09/2020.

Apotex NZ Ltd. Apo-Mirtazapine (15mg, 30mg & 45mg) data sheet 14 August 2017. Medsafe. http://www.medsafe.govt.nz/. Accessed 16/09/2020.

Buckingham R (ed). Mirtazapine. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 15/09/2020.

Joint Formulary Committee. Mirtazapine. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 15/09/2020.

Remeron Tablet, Film Coated. Remeronsoltab Tablet, Orally Disintegrating (Organon USA Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 16/09/2020.

Disclaimer: This information is independently developed by MIMS based on Mirtazapine from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to MIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, MIMS shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2020 MIMS. All rights reserved. Powered by MIMS.com
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