Drug therapy for geriatric depression.

Depression is a common problem in elderly patients. The identification and treatment of depression may be more complex in older than in younger patients because of co-existing illnesses and concurrent drug therapy. In addition, a variety of medical conditions and drugs can cause depression. The pharmacology and pharmacokinetics of the cyclic antidepressants have been extensively studied. These agents are hepatically metabolised, often to an active agent. The clearance of the parent compound and the active metabolite(s) may be reduced in elderly patients, causing drug accumulation and increased toxicity. The cyclic antidepressants interact with a variety of neurotransmitters and their receptors. While these effects explain many of the adverse effects of the cyclic antidepressants, it is not clear whether the noradrenergic and serotoninergic effects of such drugs explain their antidepressant effects. Cyclic antidepressant therapy is associated with a variety of adverse effects, including sedation, anticholinergic effects and effects caused by alpha-adrenergic blockade. The cyclic antidepressants differ in their relative ability to cause these adverse effects. The newer cyclic antidepressants such as the selective serotonin reuptake inhibitors are relatively free of sedative and anticholinergic effects, but cause insomnia, nausea and possibly cardiac arrhythmias. All cyclic antidepressants appear to be equally effective. Therefore, the choice of a cyclic antidepressant for a specific patient must be based on several factors, including the risk of adverse effects. In elderly patients, the initial dose of cyclic antidepressants should be lower than the usual dose recommended for younger adults, and titrated slowly. All antidepressants require at least 2 to 3 weeks for their antidepressant effects to be seen. Because depression is a relapsing disease, maintenance antidepressant therapy may be indicated to reduce the risk of recurrent depression. The monoamine oxidase (MAO) inhibitors are effective antidepressants, especially in atypical depression. However, the adverse effects and risk of potentially lethal drug interactions of the older agents preclude their routine use. However, the new reversible MAO inhibitors may prove to be a well tolerated alternative in older patients. Antidepressant therapy should not be avoided simply because of a patient's age. However, the clinician must be conservative in the use of cyclic antidepressants in elderly patients and monitor closely for adverse drug reactions.