Formulary
Mirtazapine: Indications, Dosing, Side Effects and Interactions
Mirtazapine is a presynaptic alpha 2 -adrenoreceptor antagonist which increases central noradrenergic and serotonergic neurotransmission.
MedNext Academy | 3 min read
Mirtazapine: Indications, Dosing, Side Effects and Interactions
Mirtazapine is a presynaptic alpha 2 -adrenoreceptor antagonist which increases central noradrenergic and serotonergic neurotransmission.
Drug action
Mirtazapine is a presynaptic alpha 2 -adrenoreceptor antagonist which increases central noradrenergic and serotonergic neurotransmission.
Indications and dose
**Major depression**
- **Adult** (By Mouth): Initially 15-30 mg once daily for 2-4 weeks, dose to be taken at bedtime, then adjusted according to response to up to 45 mg once daily, dose to be taken at bedtime, alternatively up to 45 mg daily in 2 divided doses.
Cautions
Cardiac disorders; diabetes mellitus; elderly; history of mania (discontinue if patient entering manic phase); history of seizures; history of urinary retention; hypotension; psychoses (may aggravate psychotic symptoms); susceptibility to angle-closure glaucoma
Side effects
Common or very common Anxiety; appetite increased; arthralgia; back pain; confusion; constipation; diarrhoea; dizziness; drowsiness; dry mouth; fatigue; headache (on discontinuation); myalgia; nausea; oedema; postural hypotension; sleep disorders; tremor; vomiting; weight increased Uncommon Hallucination; mania; movement disorders; oral disorders; syncope Rare or very rare Aggression; pancreatitis Frequency not known Agranulocytosis; arrhythmias; bone marrow disorders; dysarthria; eosinophilia; granulocytopenia; hyponatraemia; jaundice (discontinue); QT interval prolongation; rhabdomyolysis; seizure; serotonin syndrome; severe cutaneous adverse reactions (SCARs); SIADH; skin reactions; sudden death; suicidal behaviours; thrombocytopenia; urinary retention; withdrawal syndrome
Interactions
**Severe interactions:**
- Patients should therefore be advised to avoid alcoholic beverages while taking mirtazapine.
**Other interactions (11):**
- Pharmacodynamic interactions Mirtazapine should not be administered concomitantly with MAO inhibitors or within two weeks after discontinuation of MAO inhibitor therapy.
- In the opposite way about two weeks should pass before patients treated with mirtazapine should be treated with MAO inhibitors (see section 4.3).
- In addition, as with SSRIs, co-administration with other serotonergic active substances (L-tryptophan, triptans, tramadol, linezolid, methylene blue, SSRIs, venlafaxine, lithium and St.
- Caution should be advised and a closer clinical monitoring is required when these active substances are combined with mirtazapine.
- Caution should be exercised when these medicinal products are prescribed together with mirtazapine.
- As at a higher dose of mirtazapine a more pronounced effect cannot be excluded, it is advisable to monitor the INR in case of concomitant treatment of warfarin with mirtazapine.
Pregnancy
Use with caution-limited experience; monitor neonate for withdrawal effects.
Breast feeding
Present in milk; use only if potential benefit outweighs risk.
Hepatic impairment
Manufacturer advises caution (risk of increased plasma concentration, no information available in severe impairment).
Renal impairment
Clearance reduced by 30% if creatinine clearance less than 40 mL/minute; clearance reduced by 50% if creatinine clearance less than 10 mL/minute. See Prescribing in renal impairment .
Medicinal forms
Capsule,Tablet,Tablet,Solution
Clinical governance
**Author:** MedNext Clinical Team. **Clinical reviewer:** Dr Shameer Deen, MBBS, MS, MRCS. **Sources:** BNF, Indian Pharmacopoeia, CIMS India. **Correction:** Report errors at support@mednext.academy.
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