antidepressant drugs

Drugs that act to relieve the symptoms of moderate to severe depression. Antidepressant drugs usually need to be taken for 2 weeks before their effect is apparent, and full benefit may not be felt for 6–8 weeks. They are generally continued for 4–6 months after the depression has resolved, and if the condition is recurrent, medication may be continued for years. Most antidepressants are dangerous in overdose and should therefore be prescribed in small quantities (prescriptions for one month are common). If stopped suddenly after having been taken for eight weeks or more, withdrawal symptoms (including nausea, vomiting, and weakness) may occur. Depression is thought to be related to abnormal function of the transmitters noradrenaline and/or serotonin. After these transmitters have been released in the brain they will stimulate brain cells and then be taken up again by nerve endings, broken down, and hence inactivated. Some antidepressant drugs inhibit the reuptake mechanism, while others prevent breakdown of the transmitters; both actions result in a longer duration of action of these transmitters. The mechanism of action of other antidepressants is less clear.

Antidepressants elevate mood, increase the capacity for physical activity, improve the appetite, and restore activity in everyday life. Some antidepressants are sedative in nature and are especially useful when depression is accompanied by anxiety and insomnia. The main classes of antidepressants are the tricyclic antidepressants, the monoamine oxidase inhibitors (monoamine oxidase inhibitors), the selective serotonin reuptake inhibitors (selective serotonin reuptake inhibitors), and lithium salts. See also agomelatine; duloxetine; flupentixol; mirtazapine; reboxetine; tryptophan; venlafaxine.

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