A review of atypical antipsychotic drugs versus conventional medication in schizophrenia.

Atypical antipsychotics are replacing conventional antipsychotics for the treatment of schizophrenia. They are considered to be at least as effective as conventional agents, with most producing fewer extrapyramidal symptoms. This review presents the evidence from published meta-analyses and describes differences in clinical effectiveness and tolerability between conventional and atypical antipsychotic agents. In addition, it discusses some of the more significant adverse effects including tardive dyskinesia, weight gain, diabetes and sudden death. Results from meta-analyses are conflicting, with some finding no significant advantages on measures of efficacy or tolerability for atypical antipsychotics over moderate daily doses of conventional drugs. Other results have shown that some atypical drugs have at least minor efficacy advantages over conventional comparators. Atypical antipsychotics exhibit a much reduced risk for tardive dyskinesia compared with conventional drugs. However, weight gain is more common with some atypical drugs (especially clozapine and olanzapine). Both conventional and atypical antipsychotics have been associated with diabetes, with most reports implicating both clozapine and olanzapine. Finally, atypical antipsychotics (unlike conventional drugs) have little or no effect on QT and are not associated with sudden death.