New Formulations of Currently available Second Generation Antipsychotics

Currently, none of newer generation antipsychotic agents (clozapine, risperidone, olanzapine, quetiapine, or ziprasidone) is available in an injectable form in most countries (clozapine is licensed for parenteral administration in some countries). Injectable formulations are important because they have rapid onset of action, can be given when oral administration is precluded, and avoid some problems of patient resistance and non-compliance. Consequently, there are several clinical situations where first-generation antipsychotics have to be employed despite their many disadvantages.

Efforts to develop injectable formulations of atypical drugs are at different stages for the different agents. With regard to rapid-acting formulations for parenteral use, intramuscular olanzapine and ziprasidone have been developed and tested (Swift et al., 1998; Jones et al., 2001). Both these agents are currently being reviewed by the Food and Drug Administration (FDA) and are likely to become available within the next year. In patients whose compliance cannot otherwise be ensured, a depot antipsychotic is the treatment of choice. Currently, haloperidol decanoate and fluphenazine decanoate are the only agents available for such use in the United States. A long-acting formulation of risperidone is at a fairly advanced stage of evaluation and appears likely to become available by the year 2003/2004.

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