Treating Depression With Remeron (Mirtazapine)

Remeron (mirtazapine) is an atypical antidepressant approved by the U.S. Food and Drug Administration (FDA) for the treatment of major depressive disorder (MDD) in adults. Remeron works by increasing the production of serotonin and norepinephrine, two neurotransmitters that are known to influence moods and cognition. While effective in treating MDD, Remeron is not used to treat depression related to bipolar disorder.

Despite these benefits, Remeron poses an increased risk of suicidal thoughts and action in children, teens, and young adults. For this reason, Remeron is not commonly prescribed to anyone under 18 unless the potential benefits are seen to outweigh the risks.

Remeron is indicated for the treatment of clinical depression. A major depressive episode is defined as a prominent and persistent condition in which you feel depressed or have profound feelings of uneasiness (dysphoria) for at least two weeks.

By definition, MDD is a condition that interferes with your ability to function normally and one which must be accompanied by at least five of the following nine symptoms:

• Depressed mood
• Loss of interest in usual activities
• Significant changes in weight and/or appetite
• Insomnia or hypersomnia (excessive sleeping)
• Psychomotor agitation or retardation
• Increased fatigue
• feelings of guilt or worthlessness
• Slowed thinking or impaired concentration
• Suicidal thoughts or a suicidal attempt

Remeron is available in tablet form in dosages of 15, 30 and 45 milligrams (mg). It is also available in the same dosages as a dissolvable tablet. Generic mirtazapine is also supplied in a 7.5-milligram tablet. 

The recommended dosage for adults with MDD is as follows:

• Initial dose: Start with 15 mg once daily, usually taken before bedtime to minimize symptoms. Remeron can be taken with or without food.
• Maintenance dose: Increase the medication dose every one to two weeks until the desired effect is achieved. You should never take more than 45 mg per day.
• Seniors 65 and older: Lower doses may be prescribed due to the increased risk of kidney impairment in older adults. Regular renal function tests would need to be performed to avoid toxicity and kidney failure.

Remeron has not been confirmed to be safe in children or teens under 18. If Remeron is recommended for a younger person, ask what other treatment options are available and/or seek a second opinion to make a fully informed choice.

There are common side effects associated with all antidepressant drugs. While many go away on their own within a few days or weeks, others may persist and become intolerable. The most common side effects associated with Remeron use include:

• Sleepiness
• Increased appetite
• Weight gain (7 percent gain on average)
• Dizziness
• Constipation
• Dry mouth (xerostomia)
• Abnormal, vivid dreams

Interestingly, sedation often occurs at lower doses (15 mg) than higher ones. This is why some doctors will opt to start treatment at 30 mg doses to help minimize the sedative effect.

If side effects worsen or persist for more than two weeks, call your doctor.

Uncommon Side Effects

Remeron poses a slight risk of causing agranulocytosis, a condition in which your white blood cell count is reduced, making it more difficult to fight infection. Other less common side effects include:

• Hyponatremia (low blood sodium)
• Serotonin syndrome
• Stevens-Johnson syndrome (a potentially life-threatening drug reaction characterized by large, peeling blisters)
• Anaphylaxis (a potentially life-threatening, all-body allergy)

The FDA has issued a black box warning in 2005 advising doctors and patients about the increased risk of suicide in children, teens, and adults under 24 who take Remeron. The risk is higher if you or anyone in your family has a history of bipolar disorder.

Call your doctor or seek emergency care if you experience any of the following:

• Suicidal thoughts or actions
• Thoughts of dying
• Aggressive or violent behaviors
• New or worsening anxiety
• New or worsening panic attack
• Worsening depression
• Manic behavior and inability to sleep
• Talking faster and more frenetically than normal
• Acting on dangerous impulses
• Any unusual change in mood, thoughts, or behavior

Remeron is contraindicated in people with a known hypersensitivity to mirtazapine. Remeron should also not be used with another class of antidepressant known as monoamine oxidase (MAO) inhibitors, which includes:

• Eldepryl (selegiline)
• Marplan (isocarboxazid)
• Nardil (phenelzine)
• Parnate (tranylcypromine)
• Zyvox (linezolid)

Conversely, if you stop taking Remeron, you should wait for at least 14 days before starting an MAO inhibitor. The concomitant use of Remeron and an MAO inhibitor has been known on to trigger serious and sometimes fatal reactions, including tremors, muscle rigidity, seizures, and hyperthermia (high body temperature), and coma. 

The antibiotic Zyvox (linezolid) and intravenous methylene blue (used to treat blood oxygen problems) should be avoided due to an increased risk of serotonin syndrome.

There is a large number of drugs known to interact with Remeron. In some cases, the coadministered drug can increase the concentration of Remeron in the blood and, along with it, the severity of side effects.

Others, specifically Tegretol (carbamazepine) and Dilantin (phenytoin), have the opposite effect. Others still can enhance the psychoactive effects of the Remeron, causing increased drowsiness and dizziness.

Among some of the drugs known to interact with Remeron are:

• Alcohol
• Anticoagulants such as Coumadin (warfarin)
• Antidepressants such as Anafranil (clomipramine), Asendin (amoxapine), Aventy (nortriptyline), Elavil (amitriptyline), Norpramin (desipramine), Surmontil (trimipramine), Tofranil (imipramine), and Vivactil (protriptyline)
• Antifungals such as Nizoral (ketoconazole )
• Buspirone
• Dilantin (phenytoin)
• Erythromycin
• Fentanyl
• Lithium
• Migraine medications such as Axert (almotriptan), Relpax (eletriptan), Frova (frovatriptan), Amerge (naratriptan), Maxalt (rizatriptan), Imitrex (sumatriptan), and Zomig (zolmitriptan)
• Rifampin
• Selective serotonin reuptake inhibitors (SSRIs) such as Celexa (citalopram), Lexapro (escitalopram), Luvox (fluvoxamine), Prozac (fluoxetine), Paxil (paroxetine), and Zoloft (sertraline)
• Selective serotonin and norepinephrine reuptake inhibitors (SNRIs) such as Cymbalta (duloxetine), Effexor (venlafaxine), and Pristiq (desvenlafaxine)
• St. John's Wort
• Tagamet (cimetidine)
• Tegretol (carbamazepine)
• Ultram (tramadol)
• Valium (diazepam)

Remeron is classified as a Category C drug in pregnancy, meaning that there are no adequate clinical studies in humans but that animal research has shown an increased risk of adverse events. Low birth weight was commonly cited.

It is also not known if Remeron is transmitted in breast milk and what, if any, effect that might have on breastfeeding baby.

Because animal studies don't always correspond to the same results in human, it is important to speak with your doctor about both the potential risks and potential benefits of Remeron.