Sir: We read with great interest Dr. Sharif's report about the safety of antipsychotics in primary care.1 He states that ziprasidone and thioridazine caused a clinically significant increase of QTc. An open-label, parallel-group phase 1 study (054 study)2 found that mean QTc increases were comparable for ziprasidone and 4 other antipsychotics—haloperidol, quetiapine, risperidone, and olanzapine—at maximum steady-state plasma concentrations. In this study,2 no cardiovascular symptoms or QTc ≥ 500 ms were observed. The U.S. Food and Drug Administration has used QTc intervals ≥ 500 ms as a clinically significant cutoff. Therefore, although ziprasidone, as well as other antipsychotics (haloperidol, quetiapine, risperidone, and olanzapine), increases the QTc, this increase is not clinically significant. Apart from this, ziprasidone has not been associated with torsades de pointes, sudden death, or increased cardiac mortality.3
Footnotes
Drs. Ortega, Cano, and Díez are employees of Pfizer.
References
- Sharif ZA. Safety of antipsychotics in primary care. Primary Care Companion J Clin Psychiatry. 2003;3:3–4. [Google Scholar]
- Pies RW. Antipsychotic medications and the QT interval. Int Drug Ther Newsl. 2001;36:85–88. [Google Scholar]
- Taylor D. Ziprasidone in the management of schizophrenia: the QT interval issue in context. CNS Drugs. 2003;17:423–430. doi: 10.2165/00023210-200317060-00004. [DOI] [PubMed] [Google Scholar]