Atypical antidepressants

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Atypical antidepressants

Atypical antidepressants are called atypical because they don't fit into other classes of antidepressants. They are each unique medications that work in different ways from one another.

How atypical antidepressants work

Atypical antidepressants ease depression by affecting chemical messengers (neurotransmitters) used to communicate between brain cells. Most antidepressants work by changing the levels of one or more of these naturally occurring brain chemicals.

Like other types of antidepressants, atypical antidepressants affect neurotransmitters including dopamine (DOE-puh-mene), serotonin (ser-oh-TOE-nin) and norepinephrine (nor-ep-ih-NEF-rin). Changing the balance of these chemicals seems to help brain cells send and receive messages, which in turn boosts mood.

Atypical antidepressants approved to treat depression

Atypical antidepressants approved by the Food and Drug Administration to treat depression, with their generic names followed by brand names in parentheses, include:

  • Bupropion (Wellbutrin, Wellbutrin SR, Wellbutrin XL)
  • Mirtazapine (Remeron, Remeron SolTab)
  • Nefazodone
  • Trazodone (Oleptro)

Side effects of atypical antidepressants

Because each atypical antidepressant is unique, side effects and other characteristics of each one is different.

Bupropion can be a good choice for people who have low energy caused by depression. However, it causes or worsens anxiety in some people. It doesn't cause sexual side effects or weight gain as a number of other antidepressants do, and is sometimes prescribed to counter sexual side effects of another antidepressant. Bupropion may be a good antidepressant choice if you're trying to quit smoking. It's sometimes prescribed to ease nicotine cravings under the brand name Zyban. Side effects can include:

  • Anxiety, restlessness or agitation
  • Confusion
  • Constipation
  • Dry mouth
  • Headache
  • Increased, irregular heartbeat
  • Insomnia
  • Nausea
  • Sore throat
  • Tremor

Mirtazapine is generally taken before bed because it can make you sleepy. Like bupropion, mirtazapine may help counter sexual side effects caused by another antidepressant. Side effects can include:

  • Constipation
  • Dizziness or lightheadedness
  • Dry mouth
  • Increased appetite
  • Increased cholesterol
  • Increased or decreased blood pressure
  • Low white blood cell count
  • Sleepiness
  • Weakness
  • Weight gain

Nefazodone may help ease anxiety as well as depression. Nefazodone can make you sleepy. It seems less likely to cause sexual side effects than do some other antidepressants. Side effects can include:

  • Blurred vision
  • Confusion
  • Constipation
  • Dizziness or lightheadedness
  • Dry mouth
  • Headache
  • Low blood pressure
  • Nausea
  • Sleepiness
  • Weakness

Trazodone is a weak antidepressant that causes sleepiness and can help with anxiety. Like mirtazapine, it's usually taken at bedtime. It may be prescribed along with other antidepressants to help with sleep. Side effects can include:

  • Sleepiness
  • Headache
  • Dry mouth
  • Dizziness or lightheadedness
  • Nausea
  • Fatigue
  • Diarrhea
  • Constipation
  • Insomnia
  • Low blood pressure
  • Confusion
  • Blurred vision
  • Irregular heartbeat

Safety concerns

Atypical antidepressants are safe for most people. However, in some circumstances they can cause problems.

  • Bupropion has been linked to seizures in some people, especially at higher doses. It can also increase blood pressure. Bupropion may not be a good antidepressant for you if you have an eating disorder such as bulimia or anorexia.
  • Mirtazapine has been associated with an increase in cholesterol. Your doctor may recommend that you have periodic cholesterol tests if you take this medication.
  • Nefazodone has been linked to liver failure in some people. Don't take it if you already have liver problems. Call your doctor immediately if you're taking nefazodone and have signs and symptoms of liver failure such as yellowing of your skin or the whites of your eyes, unusually dark urine, loss of appetite, nausea or abdominal pain.
  • Trazodone has been associated with a rare condition called priapism — a persistent, usually painful erection not associated with sexual arousal. Seek emergency treatment if you have an erection that lasts for more than four hours. Priapism may require surgery to prevent damage to your penis. In rare cases, trazodone has been linked to heart rhythm problems (cardiac arrhythmias). If you have heart disease, talk to your doctor about whether this medication is safe for you.

Other things to think about before you take an atypical antidepressant include:

  • Antidepressants and pregnancy. Some antidepressants may harm your child if you take them during pregnancy or while you're breast-feeding. If you're taking an antidepressant and you're considering getting pregnant, talk to your doctor or mental health provider about the possible dangers. Don't stop taking your medication without contacting your doctor first.
  • Drug interactions. When taking an antidepressant, be sure to tell your doctor about any other medications or supplements you're taking. Some antidepressants can cause dangerous reactions when combined with certain medications or herbal remedies.
  • Serotonin syndrome. Rarely, an atypical antidepressant can cause dangerously high levels of serotonin. This is known as serotonin syndrome. It most often occurs when two medications that raise serotonin are combined. These include other antidepressants, medications for certain health conditions and the herbal supplement St. John's wort. Signs and symptoms of serotonin syndrome include confusion, rapid or irregular heartbeat, dilated pupils, fever and unconsciousness. Seek immediate medical attention if you have any of these signs or symptoms.

Suicide risk and antidepressants

The Food and Drug Administration (FDA) requires that all antidepressants carry a warning that some children, adolescents and young adults may be at increased risk of suicide when taking antidepressants. Anyone taking an antidepressant should be watched closely for worsening depression or unusual behavior — especially in the first few weeks after starting an antidepressant. Keep in mind, antidepressants are more likely to reduce suicide risk in the long run by improving mood.

Stopping treatment with atypical antidepressants

Atypical antidepressants aren't considered addictive. However, stopping antidepressant treatment abruptly or missing several doses may cause withdrawal-like symptoms. This is sometimes called discontinuation syndrome. Work with your doctor to gradually decrease your dose.

Finding the right antidepressant

Each person reacts differently to a particular antidepressant and may be more susceptible to certain side effects. Because of this, one antidepressant may work better for you than another. When choosing an antidepressant, your doctor will take into account your particular symptoms, what health problems you have, what other medications you take and what has worked for you in the past. Sometimes a combination of antidepressants may be the best treatment choice.

Inherited traits play a role in how antidepressants affect you. In some cases, DNA tests such as cytochrome P450 (CYP450) tests may give clues as to whether an antidepressant is likely to ease symptoms or cause side effects. DNA testing isn't widely used yet, but is becoming more common.

It can take a long time to find the best treatment for depression. It takes several weeks or longer before an antidepressant is fully effective and for initial side effects to ease up. You may need to try several antidepressants before you find the right one, but hang in there. With patience, you and your doctor can find a medication that works well for you.

Last Updated: 2010-12-08
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