Mirtazapine
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.
