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Understanding Antidepressants


Marijke Vroomen Durning, RN

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What to Ask About Depression

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Antidepressant medications were discovered in the 1950s, but it was only 30 years later that treatment for depression with drugs entered mainstream medicine. This was when drugs like Prozac (fluoxetine) and Paxil (paroxetine) came on the market. They seemed like miracle drugs for many people living with depression helping relieve often crippling symptoms. Overall, antidepressants are now one of the most frequently prescribed groups of drugs in the United States.

How Antidepressants Work

Antidepressants work by changing the levels of specific chemicals, called neurotransmitters, in your brain. These chemicals include serotonin, dopamine, and norepinephrine. The antidepressants either increase the level of neurotransmitters or they can affect how your brain absorbs or uses enzymes and neurotransmitters, helping relieve the signs and symptoms of depression.

Older Antidepressants: What They Do and Their Drawbacks

The first antidepressants were monoamine oxidase inhibitors (MAOIs) and tricyclics. In some people with depression, an enzyme called monoamine oxidase removes certain neurotransmitters from the brain. MAOIs prevent this from occurring. MAOIs include:

  • Isocarboxazid (Marplan)

  • Phenelzine (Nardil)

  • Selegiline (Emsam)

  • Tranylcypromine (Parnate)

Tricyclics work in a different way from MAOIs, increasing the amount of serotonin and norepinephrine in the brain by preventing them from being absorbed. There are several drugs in the tricyclic class, common ones are:

  • Amitriptyline (Elavil)

  • Clomipramine (Anafranil)

  • Desipramine (Norpramin)

While these medications helped many people who had been suffering from depression, both MAOIs and tricyclics could cause serious side effects. Some of the most common side effects of MAOIs include:

  • Diarrhea or constipation

  • Drowsiness

  • Dry mouth

  • Headache

  • Insomnia

  • Involuntary muscle jerks

  • Low blood pressure

  • Muscle cramps

  • Nausea

  • Prickling or tingling sensation in the skin

  • Reduced sexual desire

  • Weight gain

People taking MAOIs also have to be careful about what they eat and drink. Foods such as aged cheeses, cured meats, soy sauce, and tofu, are high in an amino acid called tyramine. MAOIs can interact with these foods and trigger dangerously high blood pressure.

Some of the most common side effects from tricyclics include:

  • Blurred vision

  • Constipation

  • Drowsiness

  • Dry mouth

  • Excessive sweating

  • Increased appetite and weight gain

  • Lightheadedness, caused by a drop in blood pressure

  • Sexual problems

  • Tremor

  • Urine retention

  • Weight loss

The Advantages of the Newer Antidepressants

The newer classes of antidepressants include selective serotonin reuptake inhibitors (SSRIs) and serotonin and norepinephrine reuptake inhibitors (SNRIs). These work by raising or leveling the amount of serotonin and norepinephrine in your brain. SSRIs include:

  • Fluoxetine (Prozac, Selfemra)

  • Paroxetine (Paxil, Pexeva)

  • Sertraline (Zoloft)

  • Citalopram (Celexa)

  • Escitalopram (Lexapro)

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Medical Reviewers: William C. Lloyd III, MD, FACS Last Review Date: Sep 16, 2016

© 2016 Healthgrades Operating Company, Inc. All rights reserved. May not be reproduced or reprinted without permission from Healthgrades Operating Company, Inc. Use of this information is governed by the Healthgrades User Agreement.

View Sources

Medical References

  1. Therapeutic Drug Use. Centers for Disease Control and Prevention.
  2. Lopez-Munoz F. Alamo C. Monoaminergic Neurotransmission: The History of the Discovery of Antidepressants from 1950s Until Today. Current Pharmaceutical Design. 15; 14(1563-1586). doi: 10.2174/138161209788168001
  3. Antidepressant Medication. Centre for Addiction and Mental Health.
  4. Depression – Types of Antidepressants.
  5. Monoamine oxidase inhibitors (MAOIs). Mayo Clinic.
  6. Tricyclic antidepressants. Mayo Clinic.
  7. Atypical antidepressants. Mayo Clinic.

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