What is mirtazapine?

MIRTAZAPINE (brand name Remeron) is a tetra-cyclic antidepressant. Though it is usually prescribed for major depression, there are many off-label uses, most notably to improve sleep-architecture in those with severe and/or chronic insomnia. It also posses anti-nausea, appetite-stimulating, antihistamine, anti-anxiety and strongly sedating properties, et al., though these become less noticeable with time. A notable irony is that at lower doses (<30mg) the sedative properties are greater than at higher doses (>45mg). The reason for this is, at low doses mirtazapine binds mostly with the brain's H1 receptor (the same receptor for which the sedating antihistamines have a strong affinity). At higher doses, however, mirtazapine begins to have a stimulating effect (due to the antagonizing of the alpha-2 adrenergic receptor) which partially offsets the sedative properties.

The initial dose is usually 30mg, and is adjusted based upon the patient's response to therapy; 90mg is the usually the highest recommended dose, although in severe cases, doses as high as 120mg have been found most efficacious.

Treatment for major depression with mirtazapine is recommended to continue for at least four months to gain maximum benefit. Stopping the medicine too soon can cause a return to the depressive state. If side effects are bothering you, do not stop taking mirtazapine; contact your doctor, the dose likely needs adjustment.

Mirtazapine must be discontinued very gradually and under close doctor supervision, as physical dependence will develop over time; this is especially important for patients who have used the drug at high doses and/or for long periods of time. Suddenly stopping mirtazapine may cause severe depression, insomnia, anxiety, panic attacks, (all dysphoric states) loss of appetite, worsening of allergies and rarely, manic episodes.

PJF