What are antidepressants?

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A group of drugs used for the treatment of clinical depression
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Indications and Procedures

Antidepressants are prescribed most often to individuals suffering from symptoms of clinical depression, a severe form of depression that interferes with the person’s ability to function (for example, to hold down a job or to handle the responsibilities of being a student). The symptoms of depression must be present for at least two weeks before a diagnosis is made and treatment is recommended. Depression may be treated with antidepressant medications, brief psychotherapy, or a combination of both. Antidepressants are also used in the treatment of anxiety disorders.

Several classes of antidepressants can be considered as treatment options for depression. Each class of drugs acts on the nervous system in its own unique way, and each class produces different kinds of side effects. Monoamine oxidase inhibitors (MAOIs) and tricyclic antidepressants are regarded as two different classes of first-generation drugs. These two classes and the new-generation selective serotonin reuptake inhibitors (SSRIs), including fluoxetine (Prozac), all affect the nervous system by increasing the availability of neurotransmitters such as norepinephrine or serotonin.

Although physicians have several classes of drugs at their disposal to combat the effects of depression, no single drug or class of drugs has been found to be significantly more effective in treating symptoms. In fact, no reliable test exists to discover which antidepressant will be most effective for a particular patient. However, it is clearly the case that most patients will respond favorably to one class of drugs over the others. The effectiveness of antidepressants can be evaluated on two fronts: the degree to which symptoms of clinical depression are reduced and the pervasiveness of any adverse side effects that may result from a particular medication.

Uses and Complications

Because all antidepressant medications cause some adverse side effects, physicians attempt to determine the minimum clinically effective dose. For some patients, antidepressants may cause suicidal ideation in the first few weeks of their use. Anyone taking antidepressants should be closely monitored by a physician, especially when the medication is first prescribed. Patients should discuss how they are feeling with their doctor after a new antidepressant medication is prescribed so that the physician can evaluate the effectiveness of the antidepressant and identify any adverse side effects. Because there are several different types of antidepressants available, some experimentation may be necessary to determine which medication works best for a given patient.

In terms of specific side effects of drugs, MAOIs may produce a serious adverse side effect known as a hypertensive crisis, which results in a rapid elevation of blood pressure. This condition is caused by an interaction of the drug with foods containing tyramine, such as aged cheeses, aged meats, and red wines; thus, these foods must be avoided while MAOIs are in use. Less serious side effects produced by MAOIs include constipation, diarrhea, and difficulty falling asleep.

Tricyclic antidepressants may produce dry mouth, blurred vision, or weight gain. However, the most serious aspect of tricyclics is the danger if an overdose is taken, as fatal cardiac rhythm disturbances can occur. Given that patients suffering from depression may have thoughts of suicide, the amount of prescription given at one time must be carefully monitored and should be limited. SSRIs have fewer and more easily tolerated side effects than the first-generation antidepressants, although some patients will experience weight gain and sexual dysfunction resulting in the loss of the sexual drive.

Abruptly stopping an antidepressant prescription will lead to a range of withdrawal symptoms, from feeling more depressed to becoming irritable to developing flulike symptoms. Although the withdrawal symptoms are not dangerous, it is recommended that antidepressants be reduced in dosage over a period of several days.

Perspective and Prospects

Since the late 1980s, individuals suffering from depression have had access to medications that produce fewer adverse side effects than first-generation antidepressants. Investigators are also learning that antidepressants can help patients with other psychological conditions, such as bipolar disorders, anxiety disorders, panic attacks, and obsessive-compulsive disorder.

Despite the successes that have come with the availability of several classes of antidepressants, there still remains a group of patients suffering from depression who do not benefit from them. Investigators are continuing to look for more effective treatments, particularly ones that can alleviate the symptoms of depression more quickly. Group therapy and cognitive behavioral therapy are also effective in the treatment of depression and should be used in combination with antidepressants to improve treatment outcome.

Bibliography

American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 5th ed. Arlington, Va.: American Psychiatric Association, 2013.

"Antidepressants: Selecting One That's Right for You." Mayo Clinic, November 8, 2011.

"Depression." National Institute of Mental Health, 2013.

Diamond, Ronald J. Instant Psychopharmacology: Up-to-Date Information About the Most Commonly Prescribed Drugs for Emotional Health. 3d ed. New York: W. W. Norton, 2009.

Feldman, Robert S., Jerrold S. Meyer, and Linda F. Quenzer. Principles of Neuropsychopharmacology. Sunderland, Mass.: Sinauer, 1997.

Hart, Carl, and Charles Ksir. Drugs, Society, and Human Behavior. 15th ed. New York: McGraw-Hill, 2012.

Lickey, Marvin E., and Barbara Gordon. Medicine and Mental Illness: The Use of Drugs in Psychiatry. New York: W. H. Freeman, 1991.