Antidepressant is the name of a group of drugs commonly used to treat major depression, a severe mental illness. Antidepressants also help treat other disorders, including chronic pain, anxiety disorders, and obsessive-compulsive disorder. See Depression ; Mental illness .
Antidepressants are thought to work by regulating the brain’s neurotransmission system. Chemicals called neurotransmitters carry messages from one nerve cell in the brain to another. These chemicals attach to special molecules on nerve cells called receptors, both in sending and receiving messages. Antidepressants first increase the concentration of neurotransmitters in the brain. After several weeks of treatment, the receptors become less sensitive, and depression lifts.
The three main types of antidepressants are (1) selective serotonin reuptake inhibitors (SSRI’s), (2) tricyclic antidepressants (TCA’s), and (3) monoamine oxidase inhibitors (MAOI’s). SSRI’s and TCA’s prevent brain cells from reabsorbing excess neurotransmitters after the chemicals have delivered their messages. SSRI’s block the reabsorption of the neurotransmitter called serotonin. SSRI’s include the most widely prescribed antidepressant, fluoxetine (Prozac). TCA’s, such as the drug amitriptyline (for example, Elavil), block the reabsorption of several neurotransmitters, including serotonin and norepinephrine. MAOI’s, which include the drug phenelzine (Nardil), inactivate a protein that breaks down excess neurotransmitters.
Most antidepressants are taken by mouth, and all require the prescription of a doctor. The drugs may cause various side effects. For example, SSRI’s can cause increased anxiety, poor sleep, nausea, and loss of sexual interest. TCA’s can cause hypotension (low blood pressure), irregular heartbeat, and constipation. MAOI’s may combine with certain foods or drugs to create life-threatening hypertension (high blood pressure). In addition, the United States Food and Drug Administration (FDA) requires warning labels to indicate that antidepressants could lead some patients, particularly teen-agers and children, to become suicidal. Antidepressants should be taken only under the supervision of a physician.
