BMA Concise Guide to Medicine & Drugs

Mirtazapine

Brand names Soltab, Zispin

Used in the following combined preparations None

QUICK REFERENCE

Drug group Antidepressant drug

Overdose danger rating Medium

Dependence rating Low

Prescription needed Yes

Available as generic Yes

GENERAL INFORMATION

Mirtazapine is an antidepressant drug that works by increasing the naturally occurring chemicals in the brain, serotonin and noradrenaline. It is used in the treatment of major depression, the symptoms of which may include feelings of worthlessness, anxiety, and increased or decreased appetite.

Mirtazapine may be given at a low dose initially and increased gradually according to the response of the individual. If there is no response to mirtazapine at the maximum dose within 2 to 4 weeks, the treatment may be discontinued.

Mirtazapine is available as tablets, orosoluble tablets (which are placed on the tongue and allowed to dissolve), and an oral solution. Because the drug has little anticholinergic action, it is better tolerated than tricyclic antidepressants.

INFORMATION FOR USERS

Your drug prescription is tailored for you. Do not alter dosage without checking with your doctor.

How taken/used Tablets, orosoluble tablets, liquid (oral solution).

Frequency and timing of doses Usually once daily at bedtime.

Adult dosage range 15mg (initial dose), increased gradually to 45mg, according to response.

Onset of effect Within 1–2 weeks, but full beneficial effect may not be felt for 2–4 weeks.

Duration of action At least 24 hours.

Diet advice None.

Storage Keep in original container at room temperature out of the reach of children.

Missed dose Take as soon as you remember, then return to your normal dosing schedule. Do not take an extra dose to make up.

Stopping the drug Do not stop taking the drug without consulting your doctor, who will supervise a gradual reduction in dosage. Stopping abruptly can lead to withdrawal symptoms.

Exceeding the dose An occasional unintentional extra dose is unlikely to cause problems. Larger overdoses may cause drowsiness and disorientation. Notify your doctor.

POSSIBLE ADVERSE EFFECTS

A number of mirtazapine’s effects are similar to symptoms of the illness. The drug has few anticholinergic effects but causes sedation at the start of treatment. Other common adverse effects include increased appetite and weight gain, fatigue, and swollen ankles and feet due to fluid accumulation. Notify your dotor if you experience ankle or foot swelling. Less commonly, the drug may cause restlessness, dizziness, headache, and vivid dreams or nightmares. If you develop jaundice, fever, or a sore throat, stop taking the drug and consult your doctor immediately.

INTERACTIONS

Monoamine oxidase inhibitors (MAOIs) should not be taken with, or within two weeks of stopping, mirtazapine and vice versa.

Warfarin Mirtazapine increases the anticoagulant effect of warfarin.

Antimalarials (artemether with lumefantrine) should not be taken with mirtazapine.

Carbamazepine and phenytoin may reduce blood levels of mirtazapine.

SPECIAL PRECAUTIONS

Be sure to tell your doctor if:

· You have epilepsy.

· You have liver or kidney problems.

· You have angina or have had a recent heart attack.

· You have hypertension.

· You have diabetes.

· You have a psychiatric disease or bipolar disorder.

· You have any eye diseases such as glaucoma.

· You have had a previous allergic reaction to mirtazapine.

· You are taking other medicines.

Pregnancy Not recommended. Safety not established. Discuss with your doctor.

Breast-feeding Small amounts of the drug pass into the breast milk, but safety not established. Discuss with your doctor.

Infants and children Not recommended.

Over 60 Not recommended.

Driving and hazardous work Do not undertake such activities until you have learned how mirtazapine affects you because the drug can cause initial sedation and impaired alertness and concentration.

Alcohol Avoid. Mirtazapine may increase the sedative effects of alcohol.

PROLONGED USE

No known problems.

Monitoring Periodic tests of liver function are usually carried out.