Dropout rates in patients taking SSRIs are generally two thirds to one half those of patients taking tricyclic antide-pressants. 19 The potential for a fatal overdose is significantly lower with SSRIs than with tricyclic antidepressants. SSRIs cost more than most other antidepressant agents, but this disadvantage is offset by a decreased need for inpatient and outpatient care. SSRIs have been proved to be as effective as tricyclic antidepressants in controlled clinical trials, with about 70 to 75 percent of patients responding to treatment. 19 Slight improvements in a patient’s symptoms may be detected within several days of starting treatment, but two to three months of therapy are necessary to achieve the full benefit of treatment. 20
Clozapine, olanzapine and, to a lesser extent, quetiapine may cause sedation, anticholinergic effects and orthostatic hypotension. Quetiapine has not been studied in the elderly. 18 How this drug compares with other newer antipsychotics remains to be established. 19 Risperidone is well tolerated, 18 and several studies have demonstrated its efficacy in the management of psychotic and aggressive symptoms in patients with dementia. 18 , 20 Risperidone, in dosages of to mg per day, has successfully alleviated behavioral disturbances in patients with Alzheimer's disease. 21 , 22 Clozapine is somewhat more difficult to use because of its association with agranulocytosis and the need for periodic monitoring of complete blood counts.
The intravenous route is not FDA approved and is generally not recommended except when no other alternatives are available. Intravenous administration appears to be associated with a higher risk of QT prolongation and torsade de pointes (TdP) than other forms of administration. The manufacturer recommends ECG monitoring for QT prolongation and arrhythmias if IV administration is required. A dose in the range of 1 to 5 mg IV has been suggested, with the dose being repeated at 30 to 60 minute intervals, if needed. A maximum IV dose has not been established. The lowest effective dose should be used in conjunction with conversion to oral therapy as soon as possible.