Novel antipsychotics, extrapyramidal side effects and tardive dyskinesia.

A common and serious drawback of the conventional antipsychotics is their association with a range of motor disturbances: acute extrapyramidal symptoms, including parkinsonism, acute akathisia and acute dystonia; and chronic motor problems such as tardive dyskinesia, chronic akathisia and tardive dystonia. In addition to physical disability directly related to abnormal movements, the acute movement disorders can cause considerable subjective discomfort and distress, and are frequently cited as a reason for poor compliance with medication, at least during acute treatment. They can also confound clinical assessment of mental-state phenomena because of symptom overlap with the psychotic illness being treated. The results of clinical trials of the newer antipsychotic drugs such as clozapine, risperidone, olanzapine, amisulpride, quetiapine and sertindole suggest a lower liability for acute extrapyramidal symptoms than conventional antipsychotic drugs such as haloperidol and chlorpromazine. The relative liability of each of the newer drugs to cause acute extrapyramidal side effects is not known, as they have been available for a relatively short time and there is a paucity of direct comparative studies. Evidence is accumulating that those patients exhibiting acute extrapyramidal side effects are at greater risk of developing tardive dyskinesia, which raises the hope that the newer antipsychotic drugs may also be associated with less tardive dyskinesia in the longer term. Encouraging data are already available for clozapine, which appears to have a low incidence of tardive dyskinesia, and therapeutic value in a proportion of established cases of tardive dyskinesia and tardive dystonia. Here we review the available data on atypical antipsychotics and adverse motor effects.