Antidepressants (Depression Medications)

  • Pharmacy Author:
    Omudhome Ogbru, PharmD

    Dr. Ogbru received his Doctorate in Pharmacy from the University of the Pacific School of Pharmacy in 1995. He completed a Pharmacy Practice Residency at the University of Arizona/University Medical Center in 1996. He was a Professor of Pharmacy Practice and a Regional Clerkship Coordinator for the University of the Pacific School of Pharmacy from 1996-99.

  • Medical and Pharmacy Editor: Jay W. Marks, MD
    Jay W. Marks, MD

    Jay W. Marks, MD

    Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

What is an antidepressant medication?

Depression is a serious condition that often can be effectively treated with available therapies. Many antidepressants have been developed over the years. The newer classes of antidepressants are better tolerated and associated with fewer drug interactions than the older class of antidepressants. Side effects and drug interactions are barriers to successful treatment. Some side effects of antidepressants resolve with continued use while other side effects can be managed by dose reduction or adding other therapies. Appropriate management of side effects and avoidance of drugs that may interact with antidepressants may improve the success of antidepressant therapy.

This article discusses side effects and potential drug interactions of the major antidepressant classes.

How do antidepressants work?

Antidepressants are the most prescribed drug for depression. The exact mechanism of action of antidepressants is unknown.

  • The prevailing theory is that antidepressants increase the concentration of one or more brain chemicals (neurotransmitters) that nerves in the brain use to communicate with one another.
    • The neurotransmitters affected by antidepressants are norepinephrine, serotonin, and dopamine.
    • The different classes of antidepressants differ in the neurotransmitters they affect. This determines some of their side effects and potential drug interactions.
  • All available antidepressants are effective, and for most cases of depression there is no good evidence that any antidepressant is more effective than another.
  • Side effects, potential drug interactions, and therapy compliance are major factors that influence a doctor's selection of antidepressants for a patient.

How do selective serotonin reuptake inhibitors (SSRIs) work?

SSRIs are the most widely used class of antidepressants. They work by increasing the level of serotonin in the brain. Unlike MAOIs and TCAs, SSRIs do not significantly affect norepinephrine levels in the brain. SSRIs also have fewer and milder side effects, fewer drug interactions, and are much less likely to be associated with suicide than TCAs.

What are the side effects of SSRIs?

  • Headaches: SSRIs cause headaches and dose-related nausea, vomiting, and diarrhea that improve with continued treatment.
  • Insomnia, restlessness, agitation: Insomnia, restlessness, and agitation-which decrease over time-also are associated with SSRIs. Insomnia can be treated with low dose (50-100 mg) trazodone (Desyrel) at bedtime and agitation may be managed by reducing the SSRI dose or treating with anti-anxiety drugs.
  • Sexual dysfunction: SSRIs also are associated with sexual dysfunction. Symptoms of sexual dysfunction in men may be treated with sildenafil (Viagra), yohimbine (Pausinystalia yohimbe), amantadine (Symmetrel), cyproheptadine, or neostigmine (Prostigmin).
  • Weight gain or loss: Over time, weight loss or weight gain has been associated with SSRIs. Patients may experience weight loss initially but quickly regain weight.

What drugs interact with SSRIs?

What are examples of SSRIs?

Medically Reviewed by a Doctor on 10/14/2016

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