Mirtazapine

Antidepressant Drug

Drug class: Atypical Antidepressants

Mirtazapine (Remeron)（中文：米氮平）

Pronunciation

Mirtazapine orodispersible 15mg

Common Strengths of Mirtazaoine

Mirtazapine are available in the following strengths:

• 15 mg
• 30 mg

Drug Trade Names of Mirtazapine

• Remeron
• Remeron SolTab (orally disintegrating tablet)

Drug Usage

Mirtazapine is primarily used to treat major depressive disorder in adults. It is also used off-label for conditions such as insomnia, anxiety disorders, and to stimulate appetite.

Mechanism of Action

Mirtazapine works by antagonizing central presynaptic alpha-2-adrenergic receptors, which increase the release of norepinephrine and serotonin. It also blocks certain serotonin receptors (5HT2 and 5-HT3), contributing to its antidepressant effects.

Route of Administration

Mirtazapine is administered orally, available in regular tablets and orally disintegrating tablets.

Dosages

• Initial dose: 15 mg once daily, preferably at bedtime.
• Maintenance dose: 15 to 45 mg once daily, with a maximum of 45 mg/day.

Side Effects

Frequency	Adverse reactions
Common	Drowsiness/sedation
	Increased appetite
	Weight gain
	Dizziness
	Dry mouth
	Constipation
	Nausea
Serious	Suicidal thoughts and behaviors (especially in young adults)
	Serotonin syndrome (confusion, fast heart rate, agitation)
	Agranulocytosis (severe reduction in white blood cells)
	Seizures
	Angle-closure glaucoma (eye pain, blurred vision)
	Severe allergic reactions (rash, hives, swelling, trouble breathing)
	Low blood sodium levels (nausea, vomiting, headache)
	Mania/hypomania (irritability, racing thoughts, decreased need for sleep)
	Severe skin reactions (blistering, peeling skin)
	Increased liver enzymes
	QT prolongation which may lead to irregular heartbeats and fainting

Pharmacokinetics

• Absorption: Well absorbed, with peak plasma concentrations occurring within 2 hours.
• Metabolism: Extensively metabolized in the liver primarily by CYP2D6 and CYP3A4.
• Elimination Half-Life: Ranges from 20 to 40 hours.
• Onset Time: Effects may be observed within 1 week, but full antidepressive effects may take 4 to 6 weeks.

Drug Precautions

Pregnancy

Use only if the benefit outweigh the risks.

Breastfeeding

Excreted in breast milk; caution is advised.

Children and Elderly

Not approved for pediatric use; elderly may experience increased sensitivity and require dose adjustments.

Monitoring Requirements

Monitor for signs of agranulocytosis, liver function, and symptoms of serotonin syndrome.

Drug Interaction Pregnancy

Use only if the benefits outweigh the risks.

Breastfeeding

Excreted in breast milk; caution is advised.

Children and Elderly

Not approved for pediatric use; elderly may experience increased senmsitivity and require dose adjustments.

Monitoring Items

Monitor for signs of agranulocytosis, lover function, and symptoms of serotonin syndrome.

Drug Interactions

Medications that may interact with mirtazapine include:

• Antidepressants: SSRIs/SNRIs (e.g. fluoxetine, duloxetine) - Increased risk of serotonin syndrome.
• Benzodiazepines: Lorazepam, alprazolam - Increased sedative effects.
• Antipsychotics: Aripiprazole, quetiapine - Potential for increased sedation and other side effects
• Pain Medications: Tramadol, fentanyl - Risk of serotonin syndrome and increased sedation
• Antihistamines: Diphenhydramine (Benadryl) - Increased sedation.

FAQ

How Should I Take the Tablet?

Take mirtazapine exactly as prescribed, usually once daily at bedtime. It can be taken with or without food.

What Should I Avoid While Taking?

Avoid alcohol, as it can increase side effects. Be cautions when driving or operating machinery until you know how mirtazapine affect you.

What Happens if I Miss a Dose?

Take the missed dose as soon as you remember; but skip it if it is almost time for your next dose. Do not take two doses at once.