Adult: Initially, 30-40 mg daily in divided doses or as a single dose at bedtime. Dose may be increased gradually as necessary. Usual effective dose: 30-90 mg daily. Dosage recommendations may vary among individual products and between countries (refer to specific product guidelines). Elderly: Initially, 30 mg daily in divided doses or as a single dose at bedtime. Dose may be increased gradually as necessary.
What are the brands available for Mianserin in Thailand?
Mania. Severe liver disease. Concomitant use or within 14 days of discontinuing MAOIs. Lactation.
Special Precautions
Patient with history of suicide-related events or with significant degree of suicide ideation; decreased gastrointestinal motility, increased IOP, angle-closure glaucoma, visual problems, paralytic ileus, urinary retention, BPH, xerostomia; risk factors for orthostatic hypotension; risk for QT prolongation or torsades de pointes (e.g. congenital long QT syndrome); risk factors for seizures (e.g. history of seizures, head trauma, brain damage, alcoholism); history of CV disease (e.g. recent MI, arrhythmia, heart block); diabetes mellitus, bipolar disorder, phaeochromocytoma, prostatic hypertrophy. Patient undergoing surgery. Avoid abrupt withdrawal. Renal and mild to moderate hepatic impairment. Elderly. Pregnancy.
Adverse Reactions
Significant: Suicidal thinking and behaviour; anticholinergic effects (e.g. constipation, xerostomia, blurred vision, urinary retention); CNS depression, bone fractures, orthostatic hypotension, QT prolongation, ventricular arrhythmia; precipitate a shift to mania or hypomania (particularly in patients with bipolar disorder); lower seizure threshold; discontinuation syndrome (particularly if abruptly discontinued). Rarely, bone marrow suppression. Gastrointestinal disorders: Xerostomia, constipation. General disorders and administration site conditions: Oedema, fatigue, weakness. Hepatobiliary disorders: Liver function disturbances, mild jaundice. Metabolism and nutrition disorders: Hyponatraemia. Musculoskeletal and connective tissue disorders: Arthralgia, polyarthropathy, arthritis. Nervous system disorders: Drowsiness, dizziness, tremors, convulsions, lethargy, headache. Reproductive system and breast disorders: Gynaecomastia, nipple tenderness, non-puerperal lactation. Skin and subcutaneous tissue disorders: Skin rash, sweating. Vascular disorders: Postural hypotension.
Patient Counseling Information
This drug may cause drowsiness or reduced alertness, if affected, do not drive or operate machinery.
Monitoring Parameters
Correct hypokalaemia and hypomagnesaemia prior to therapy. Evaluate mental status and suicide ideation prior to treatment initiation and during dose adjustments. Monitor CBC every 4 weeks during the 1st 3 months of therapy, then periodically or if there are signs of infection; heart rate, blood pressure, ECG (especially in the elderly, those with preexisting cardiac disease, or at risk of QT prolongation); electrolytes (e.g. potassium, magnesium), blood glucose; liver and kidney function. Closely monitor for signs and symptoms of infection; clinical worsening, suicidality, or any unusual behavioural changes during the 1st 1-2 months of therapy and during dose adjustments.
Overdosage
Symptoms: Nausea, vomiting, dry mouth, constricted or dilated pupils, nystagmus, ataxia, dizziness, drowsiness, slow tendon reflexes, prolonged sedation, CV effects (e.g. bradycardia, tachycardia, hypotension, hypertension), respiratory depression, ECG abnormalities (e.g. ST elevation), 1st degree to complete heart block, convulsions, coma. In severe cases, ventricular fibrillation and cardiac arrest. Management: Symptomatic and supportive treatment. May administer activated charcoal within 1 hour of ingestion of >5 mg/kg bodyweight. Obtain and check urea, electrolyte and glucose levels. Perform 12-lead ECG, and in case of abnormalities, perform ABG test. Monitor blood pressure, pulse and cardiac rhythm. Manage hypotension by elevating the foot of the bed and administering an appropriate fluid challenge. If severe hypotension persists despite performing appropriate measures, may consider central venous pressure monitoring. If hypotension is primarily caused by decreased systemic vascular resistance, may consider drugs with α-adrenergic activity (e.g. norepinephrine or high dose dopamine). If hypotension is caused by decreased cardiac output, may consider inotropic drugs (e.g. dobutamine) or in severe cases, may consider epinephrine. Administer IV atropine for symptomatic bradycardia. May consider dobutamine or isoprenaline for bradycardia due to hypotension; temporary pacemaker insertion may be needed or may use external pacing. Administer IV diazepam or lorazepam for frequent or prolonged convulsions; may consider phenobarbital if unresponsive to initial treatment. Alternatively, may administer phenytoin.
Drug Interactions
Decreased plasma concentration with carbamazepine and phenytoin. May antagonise the anticonvulsant effect of antiepileptics, barbiturates, primidone. Increased risk of convulsions with atomoxetine. Increased hypotensive effect with diazoxide, hydralazine, nitroprusside. May increase the antimuscarinic effect of antihistamines and antimuscarinics. Additive CNS depressant effect with barbiturates. May affect the metabolism of coumarin derivatives (e.g. warfarin). Potentially Fatal: Increased neurotoxic effects with MAOIs.
Food Interaction
May potentiate the CNS depressant effect of alcohol.
Action
Description: Mechanism of Action: Mianserin is a tetracyclic antidepressant. It blocks presynaptic adrenergic α2-receptors and inhibits noradrenaline reuptake, thereby increasing central noradrenergic neurotransmission. Additionally, mianserin acts on serotonergic receptors in the CNS and exhibits antihistaminic and α1-adrenergic antagonistic activity. Pharmacokinetics: Absorption: Readily absorbed from the gastrointestinal tract. Bioavailability: Approx 20-70%. Time to peak plasma concentration: Approx 3 hours. Distribution: Widely distributed throughout the body; crosses the blood-brain barrier. Crosses the placenta and enters breastmilk. Plasma protein binding: Approx 95%. Metabolism: Metabolised in the liver via aromatic hydroxylation, N-oxidation, and N-demethylation into active metabolites, desmethylmianserin and 8-hydroxymianserin; undergoes extensive first-pass metabolism. Excretion: Mainly via urine; faeces (limited amount). Elimination half-life: Approx 6-61 hours.
Chemical Structure
Mianserin Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 4184, Mianserin. https://pubchem.ncbi.nlm.nih.gov/compound/Mianserin. Accessed July 29, 2025.
Storage
Store below 25°C. Protect from light and moisture.
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