Use of Atypical Antipsychotics on an As-Needed Basis

Abstract

Objective:

To review the literature and determine whether atypical antipsychotics should be used on an as-needed (prn) basis.

Data Sources:

Pertinent English-language literature dealing with atypical antipsychotics, typical antipsychotics, phamacokinetics, and prn dosing strategies was retrieved from a MEDLINE search (1960–1995).

Data Extraction:

Articles that discussed either pharmacokinetic parameters or the rationale for using antipsychotics on a prn basis.

Data Synthesis:

Administration of typical antipsychotics on a prn basis, either alone or in combination with scheduled antipsychotics, is a common practice. However, it has recently been recognized that the atypical agents, clozapine and risperidone, are also being prescribed for prn dosing. Clozapine has a sedative component that may provide a therapeutic benefit when prescribed prn, but it is also associated with dose-related seizures and orthostatic hypotension. Risperidone does not appear to exhibit sedation, except at very high doses.

Conclusions:

The risk-to-benefit ratio is not acceptable in using the atypical antipsychotic agents on a prn basis. There are documented safety and efficacy data that support the use of the typical antipsychotic agents such as chlorpromazine, or haloperidol in combination with lorazepam, on a prn basis. These latter choices are also more cost-effective.