MITAZAPINE

Indications

Mirtazapine is an antidepressant used to treat major depression. It can be especially helpful when depression comes with poor sleep, anxiety or poor appetite.

How It Works

It increases the activity of two brain chemicals, noradrenaline and serotonin, which help control mood. It also blocks histamine, which explains its sleep-inducing and appetite-increasing effects.

Dosage and Administration

Adults: usually 15 mg once a day at bedtime, increased if needed to 30 mg, and up to a maximum of 45 mg a day, as prescribed. Swallow with water, with or without food. It usually takes 2 to 4 weeks to start helping, and treatment normally continues for at least 6 months after feeling better. Do not stop suddenly; the doctor will reduce the dose gradually. It is not normally used in children and teenagers under 18.

Interactions

• Do not use with MAO inhibitors (such as Selegiline or Linezolid) or within 14 days of stopping them.
• Other medicines that raise serotonin, such as Fluoxetine, Sertraline, Tramadol, Triptans and St John's wort, increase the risk of serotonin syndrome.
• Alcohol, Diazepam and other sedatives add to drowsiness.
• Ketoconazole, Clarithromycin and some HIV medicines raise mirtazapine levels; Carbamazepine, Phenytoin and Rifampicin lower them.
• It can increase the effect of Warfarin; INR should be checked.

Contraindications

Allergy to mirtazapine, and current or recent (within 14 days) use of MAO inhibitors.

Side Effects

Common: increased appetite and weight gain, sleepiness (especially in the first weeks), dry mouth, dizziness, tiredness, constipation, headache and swelling of the ankles.

Get urgent medical help for fever, sore throat or mouth ulcers (which can mean a low white blood cell count), yellowing of the skin or eyes, a seizure, a severe skin rash with blisters, or confusion, agitation, shaking, sweating and a fast heartbeat (possible serotonin syndrome). Worsening depression or any thoughts of harming yourself, especially in the first weeks or after a dose change, need urgent contact with a doctor.

Pregnancy and Lactation

Tell the doctor if you are pregnant or planning a pregnancy; the doctor will weigh the benefits and risks, and the newborn may need monitoring if it was used near delivery. Small amounts pass into breast milk; it may be used while breastfeeding on a doctor's advice, watching the baby for sleepiness and poor feeding.

Precautions and Warnings

• It causes drowsiness; do not drive or use machines until you know how it affects you.
• Take care in epilepsy, liver or kidney disease, heart disease, low blood pressure, diabetes, glaucoma, difficulty passing urine, or bipolar disorder.
• Stopping suddenly can cause dizziness, nausea, anxiety and sleep problems.
• Family members should watch for unusual changes in mood or behaviour.

Overdose

Overdose usually causes heavy sleepiness, confusion and a fast heartbeat; it can be more dangerous when taken with other medicines or alcohol. Get emergency medical help at once.

Therapeutic Class

Antidepressant (noradrenergic and specific serotonergic antidepressant, NaSSA).

Storage

Store below 30°C in a dry place, away from light and out of the reach of children.