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Mirtazapine Antidepressant Information

Bipolar Medications Library


Updated May 16, 2014

Mirtazapine is an antidepressant that is chemically unrelated to other antidepressants; thus it is classed as an atypical antidepressant. Also sold under the brand name Remeron, the antidepressant mirtazapine operates by stimulating production of serotonin and norepinephrine, two brain hormones related to depression. At the same time it blocks certain receptors associated with side effects that are problematic with some other types of antidepressants, including lowered sex drive, nausea, nervousness, headache, insomnia, and diarrhea.

Both Remeron and mirtazapine are available in tablet form in dosages of 15, 30 and 45 milligrams. Remeron is also available in the same dosages as Remeron SolTabs®, an oral medication that disintegrates on the tongue in a matter of a few seconds. It is recommended that patients start with the lowest dosage.

Mirtazapine - Major Precautions and Warnings
Like all other antidepressants, mirtazapine carries a black box warning relating to the increased risk of suicide and suicidal behavior in children and teenagers. Unlike most other antidepressants, mirtazapine has a slight risk of causing agranulocytosis, a condition where the white blood cell count is lowered and the body has difficulty fighting off infections.

More than half the patients who took this antidepressant in the Remeron clinical trials experienced sleepiness; thus, it is recommended that mirtazapine be taken at bedtime. The prescribing information states that Remeron "may impair judgment, thinking, and particularly, motor skills, because of its prominent sedative effect. The drowsiness associated with mirtazapine use may impair a patient's ability to drive, use machines or perform tasks that require alertness." Patients should not engage in such activities until they have evaluated the effects of taking mirtazapine or Remeron. Alcoholic beverages can worsen the sedation and dizziness some people experience; thus, patients are advised not to drink alcohol. They are also advised to avoid benzodiazepines, which can also increase these effects.

Gender and Age Variables With Mirtazapine
The mean half-life of mirtazapine is significantly higher for females than males - 37 hours in females, 26 hours in males. By contrast, in elderly patients, the time for Remeron to clear the system is increased by 40% in males and just 10% in females.

Kidney and Liver Function
In patients with impaired kidney (renal) or liver (hepatic) function, it takes longer for Remeron to be cleared out of the body; therefore, in such patients the dosage should be adjusted down accordingly.

Weight Gain With Mirtazapine
In controlled trials, increased appetite was experienced by 17% of patients, and 7.5% of patients reported gaining at least 7% of their body weight. Anecdotal evidence suggests that significantly greater weight gain is possible.

Mirtazapine for Treatment-Resistant Depression
In spite of the warnings about Remeron, patients who have not had success with more traditional antidepressants such as SSRIs and tricyclics may want to give Remeron / mirtazapine a try since it works differently from the others.

Disclaimer: This is not intended to be all-inclusive or to replace information provided by your doctor or with the prescription from the manufacturer.

Healthyplace.com (1997). Additional Antidepressants for Depression. Retrieved 9/9/06. [no longer online].

Remeron.com (2006). Prescribing Information for Remeron SolTabs. Retrieved 9/9/06 from http://www.remeronsoltab.com/Authfiles/Images/292_73427.pdf (PDF).

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