Injectable Schizophrenia Medications: The Old vs the New

Schizophrenia medications paliperidone palmitate and haloperidol decanoate had similar failure rates

/ Author:  / Reviewed by: Robert Carlson, M.D Beth Bolt, RPh

(RxWiki News) Schizophrenia can be treated with oral or injectable medications. The injections last longer and may help to keep patients from stopping treatment. But it's still unclear if newer injectable medications work better than the older ones.

Medications used to treat schizophrenia can cause uncontrolled movements, similar to those seen in Parkinson’s disease, and some patients feel a sense of restlessness, called akathisia.

A recent clinical trial tested how well a new medication — called paliperidone palmitate (brand name Invega Sustenna) — treated schizophrenia compared to an older medication known as haloperidol decanoate. The researchers also compared the side effects of the two medications.

Published results showed that monthly injections of paliperidone palmitate and haloperidol decanoate were similarly effective at treating schizophrenia.

The patients who took paliperidone palmitate gained weight, and the patients in the group taking haloperidol decanoate reported more akathisia.

"Ask your psychiatrist about your options for treating schizophrenia."

This research was conducted by a team led by Joseph P. McEvoy, MD, from the Department of Psychiatry and Health Behavior at the Georgia Regent University in Augusta, Georgia.

The researchers recruited 311 patients aged 18 to 65 with schizophrenia for their study. These patients were divided into two groups: One group received monthly injections of haloperidol decanoate, and one group of patients received monthly injections of paliperidone palmitate.

The injections lasted up to 24 months. Neither the doctor nor the patient knew which medication the patient received.

Over the course of the study, similar numbers of patients in each group dropped out of the research. Forty-two patients treated with paliperidone palmitate and 36 treated with haloperidol decanoate felt that their medication was not working and cited that reason for dropping out of the study.

Fifteen patients in the paliperidone palmitate group and 14 in the haloperidol decanoate group cited unacceptable side effects as their reason for dropping out of the study.

The research team collected information on the patients, including weight, blood tests, involuntary movements experienced by the participants, akathisia and severity of schizophrenia symptoms.

Dr. McEvoy and his team noted whether the study medications were effective or not. Two indications that a medication failed to be effective were if patients were hospitalized for psychiatric reasons or if doctors discontinued the study medication due to lack of effect.

The results showed that each medication had a similar failure rate. The failure rate was 34 percent in the paliperidone palmitate group and 32 percent in the haloperidol decanoate group.

There were no statistically significant differences in the abnormal involuntary movements between the two treatment groups.

However, fewer patients in the paliperidone palmitate group started taking medications for Parkinson’s-type movements and akathisia than those taking haloperidol decanoate.

By six months into the study, the group of patients taking paliperidone palmitate gained weight, and the haloperidol decanoate group had lost weight.

The authors noted that one limitation of their study was the fact that they did not ask patients if the treatment they received made them feel better than before they were in the study.

Additionally, the study did not compare medications taken by mouth with the monthly injectable medications.

Another limitation of the study was that costs of the medications were not compared. Paliperidone palmitate is more expensive than haloperidol because haloperidol decanoate is available as a generic medication.

In an accompanying editorial on this study, Donald C. Goff, MD, wrote that patients may try one medication after another to find one that they feel treats their schizophrenia. He felt that this approach may not be the best one to use because side effects from one medication, such as weight gain or involuntary movements, may not go away before the patient tries another medication.

Dr. Goff wrote that the study by Dr. McEvoy and his team suggested that possible side effects can be more important to consider than effectiveness when choosing a medication to treat schizophrenia.

This study was published online May 20 in JAMA.

Funding for the study was provided by the National Institute of Mental Health.

Two of the study's authors — Matthew Byerly, MD, and Robert A. Rosenbeck, MD — reported receiving fees from Janssen, manufacturers of paliperidone palmitate.

Review Date: 
May 18, 2014
Last Updated:
May 20, 2014