Treating Depression With Remeron (Mirtazapine)

Remeron (mirtazapine) is an atypical antidepressant approved by the 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 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 that cause significant distress and impact one's functioning.

Other symptoms of clinical depression include:

• Feelings of guilt or worthlessness
  
• Increased fatigue
• Insomnia or hypersomnia (excessive sleeping)
  
• Psychomotor agitation or retardation
• Significant changes in weight and/or appetite
• Slowed thinking or impaired concentration
• Suicidal thoughts or a suicide 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-mg 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:

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

If side effects worsen or persist, call your doctor.

Uncommon Side Effects

Remeron poses a rare risk of causing agranulocytosis, a potentially fatal condition in which your white blood cell count is reduced, making it more difficult to fight infection. Other uncommon but serious side effects include:

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

Black Box Warning

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

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

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

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 inhibitors (MAOIs), 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 MAOI. The concomitant use of Remeron and an MAOI 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)
  
• Antifungals such as Nizoral (ketoconazole )
• Buspirone
• 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)
• Tricyclic antidepressants such as Anafranil (clomipramine), Asendin (amoxapine), Aventy (nortriptyline), Elavil (amitriptyline), Norpramin (desipramine), Surmontil (trimipramine), Tofranil (imipramine), and Vivactil (protriptyline)
• Ultram (tramadol)
• Valium (diazepam)

Other Considerations

Animal studies suggest that Remeron may be dangerous to take during pregnancy, but there are no adequate clinical studies in humans to confirm those findings. You should talk with your physician about the potential risks and benefits of continuing to take Remeron during pregnancy.

Remeron may be present in breastmilk, so nursing parents should also be cautious about using this medication. It's unclear whether or not breast milk from people taking Remeron is harmful to infants, so lactating people should discuss its use with their doctors.