Little difference found in effectiveness of two antipsychotic drugs used for schizophrenia

June 13, 2014

A UNC researcher and his colleagues have found little difference in the efficacy and side effects of two widely prescribed antipsychotic drugs, one of which came into use within the last five years.

Robert M. Hamer, PhD, research professor of biostatistics at UNC Gillings School of Global Public Health and of psychiatry in the UNC School of Medicine, collaborated with a team of researchers, including lead author Joseph P. McEvoy, MD, of the psychiatry and health behavior department at Georgia Regents University, and senior author T. Scott Stroup, MD, MPH, of Columbia University College of Physicians and Surgeons’ psychiatry department and the New York State Psychiatric Institute.

The researchers compared the effectiveness of a second-generation, long-acting injectable version of paliperidone palmitrate (PP), which was introduced in 2009, with an older similar antipsychotic, haloperidol decanoate (HD). The study found that among adults with schizophrenia, treatment with PP did not result in a statistically significant difference in efficacy failure. Their findings were published in the May 21 issue of the Journal of American Medical Association. 

A recent study found little difference in the efficacy and side effects of two antipsychotic drugs, paliperidone palmitrate, introduced in 2009, and an older similar drug, haloperidol decanoate.

Efficacy failure is defined as a psychiatric hospitalization, a need for crisis stabilization or a substantial increase in the number of outpatient visits, among other results. Long-acting injectable antipsychotic medications are prescribed to help keep patients on their medication and reduce relapse in people diagnosed with a schizophrenia-spectrum disorder. Long-acting injectable versions of HD and older antipsychotic medications have been available for decades.

Trials and analyses of newer antipsychotic drugs such as PP have raised questions about the drugs’ safety and effectiveness. Their use has been linked to side effects that include weight gain, elevated cholesterol levels and susceptibility to diabetes mellitus.

While drugs such as HD can have similar side effects, PP has some logistical advantages. The latter drug can be administered monthly and does not require costly storage or reconstitution measures.

The study, which involved 311 patients, used oral and injection methods. Patients were adults between the ages of 18 and 65 who had been diagnosed with schizophrenia or schizo-affective disorder.

According to the research team, the results of the study do not rule out the possibility of a clinically meaningful difference in the drugs. However, the results are consistent with previous research that has not found large differences in the effectiveness of newer and older antipsychotic medications.

Hamer was joined on the study by Rosalie Dominik, DRPH, research associate professor, and Neepa Ray, MS, and Tania M. Wilkins, MS, all of the Gillings School’s biostatistics department; Peter F. Buckley, MD, of the psychiatry and health behavior department at Georgia Regents University; Matthew Byerly, MD, of UT Southwestern Medical Center’s psychiatry department; Marvin S. Swartz, MD, of Duke University’s Division of Social and Community Psychiatry; Robert A. Rosenheck, MD, of Yale School of Medicine’s Northeast Program Evaluation Center; and J. Steven Lamberti, MD, of the University of Rochester School of Medicine and Dentistry’s psychiatry department.