Mirtazapine Milpharm Limited (Mirtazapine)

• Mirtazapine is indicated for the management of major depressive disorder, a psychiatric condition marked by persistent low mood, diminished interest or pleasure, and associated cognitive and somatic symptoms that impair daily functioning.
• Major depressive disorder: alleviates depressive symptoms, improves mood, and enhances functional capacity.
• Depressive disorder with insomnia: helps improve sleep quality while treating depressive symptoms.
• Depressive disorder with loss of appetite or weight loss: may stimulate appetite and promote weight gain.
• Clinical trials have demonstrated efficacy in reducing depressive scores and improving overall quality of life.

• Mirtazapine acts primarily as an antagonist at central presynaptic α2‑adrenergic receptors, which disinhibits norepinephrine release. It also blocks postsynaptic 5‑HT2 and 5‑HT3 receptors while antagonizing histamine H1 receptors. The combined effect increases synaptic concentrations of norepinephrine and serotonin, enhancing mood and alleviating depressive symptoms. Additionally, by inhibiting 5‑HT2 and 5‑HT3 receptors, mirtazapine reduces anxiety, nausea, and sleep disturbances often associated with depression.

Mirtazapine may cause a range of adverse reactions, varying from mild to serious.

Common Side Effects

• Drowsiness or sedation
• Increased appetite leading to weight gain
• Dry mouth
• Constipation
• Dizziness
• Peripheral edema

Serious or Rare Side Effects

• Agranulocytosis or neutropenia
• Severe hypersensitivity reactions (e.g., Stevens‑Johnson syndrome)
• Seizures
• Emergence of suicidal thoughts or behaviors
• Hepatic dysfunction or jaundice

When prescribing or dispensing mirtazapine, several safety considerations should be observed.

• Dose initiation: start at a low dose to minimize sedation.
• Monitor weight: significant weight gain may occur during therapy.
• Assess for suicidal ideation: especially during the early treatment phase.
• Avoid abrupt discontinuation: taper the dose to prevent withdrawal symptoms.
• Use caution in hepatic impairment: dose adjustment may be required.
• Store at ambient temperature: keep in the original container, protect from moisture and light.

Mirtazapine can interact with other medicines, requiring careful assessment.

Major Interactions (Avoid)

• Concurrent use with MAO inhibitors: risk of serotonin syndrome.
• Combination with CNS depressants (e.g., benzodiazepines, alcohol): enhanced sedation and respiratory depression.
• Co‑administration with strong CYP2D6 inhibitors (e.g., fluoxetine, paroxetine): increased mirtazapine plasma concentrations.

Moderate Interactions (Monitor Closely)

• Combination with other antidepressants (SSRIs, SNRIs): monitor for additive serotonergic effects.
• Use with warfarin: may alter anticoagulant effect; monitor INR.