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 influencing serotonin and norepinephrine, two neurotransmitters that are known to influence moods, anxiety, and cognition. While effective in treating MDD, Remeron needs to be used with caution in treating depression related to bipolar disorder as antidepressants can potentially lead to mania or a worsening mood course in this condition.

Indications

Remeron is indicated for the treatment of clinical depression. A major depressive episode is defined as at least two weeks of persistently depressed mood or loss of interest accompanied by several other symptoms causing significant distress and impacting ones functioning.

Other symptoms include:

• 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

Dosage

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: Remeron is often started with 15 mg once daily, usually taken before bedtime to minimize symptoms. Remeron can be taken with or without food.
• Maintenance dose: The medication is generally increased every one to two weeks until the desired effect is achieved. The maximum dose is considered 45 mg per day.
• Seniors 65 and older: Lower doses may be prescribed in older patients due to the greater likelihood of decreased renal function.

Side Effects

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. There are several common side effects associated with Remeron use:

• Sleepiness
• Increased appetite
• Weight gain
• Dizziness
• Constipation
• Dry mouth (xerostomia)

Interestingly, sedation often occurs at lower doses (15 mg) than higher ones.

If side effects worsen or persist, call your doctor.

Uncommon Side Effects

Remeron poses a rare risk of causing agranulocytosis, a condition in which your white blood cell count is reduced, making it more difficult to fight infection. Other uncommon 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)

Black Box Warning

The FDA issued a black box warning advising doctors and patients about the increased risk of suicide behavior in some children, teens, and young adults taking antidepressants.

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

Contraindications

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)

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 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.

Drug Interactions

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 potentially 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)

Other Considerations

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. You should talk with your physician about the potential risks and benefits of continuing your Remeron during pregnancy.

Nursing mothers should also be cautious about using Remeron. There are no serious reports showing that breastmilk from mothers taking Remeron is harmful, but lactating women should discuss its use with their doctors.