API

Mirtazapine

Drug classification

Dosage form

Tablet

API strength per dosage

15 mg

Dose

For adults, the usual starting dose is 15 mg once daily at bedtime, titrated up to 30–45 mg daily as needed. Not recommended for children and adolescents. In elderly or those with hepatic or renal impairment, initiate at lower doses and titrate cautiously.

Mechanism of action

Antagonizes central presynaptic α2-adrenergic autoreceptors and heteroreceptors, increasing norepinephrine and serotonin release; blocks postsynaptic 5-HT2 and 5-HT3 receptors, enhancing 5-HT1A–mediated neurotransmission; antagonizes H1 histamine receptors, causing sedation; weakly blocks muscarinic and peripheral α1-adrenergic receptors.

Indications

Major depressive disorder, depressive episodes.

Side effects

Pregnancy category

Precautions

Suicidal ideation risk, serotonin syndrome, agranulocytosis, hepatic impairment, renal impairment, seizure disorders, bipolar disorder, angle-closure glaucoma, elderly patients, drowsiness, weight gain, hyponatremia, withdrawal symptoms, concomitant MAOI use, alcohol or CNS depressant use, pregnancy, breastfeeding.

Contraindications