Monthly Shot Treats Schizophrenia

Injectable Drug Could Make Treatment Plan Easier to Follow

By Charlene Laino
WebMD Health News

Reviewed By Louise Chang, MD

May 6, 2008 (Washington) — A new, once-a-month shot shows promise for the treatment of schizophrenia.

The new drug is called paliperidone palmitate. It's an injectable form of the second-generation, or "atypical," antipsychotic medication Invega.

A study pitting injectable paliperidone palmitate against placebo was halted early because of its clear benefit in preventing relapses, says David Hough, MD.

Hough is a psychiatrist who led the study while at Johnson & Johnson, which makes paliperidone palmitate and funded the work.

The study involved more than 300 people with schizophrenia whose condition stabilized when they were given injectable paliperidone palmitate for six months. Then, half were randomly assigned to continue the drug and the other half to a placebo.

Over the next year, 40% of those taking placebo relapsed, Hough tells WebMD. In contrast, only 10% to 15% of those given injectable paliperidone palmitate relapsed.

The most common side effects were weight gain and stomach flu.

The findings were presented at the annual meeting of the American Psychiatric Association.

Second-Generation Antipsychotics

Schizophrenia afflicts about 2.4 million American adults in a given year. Typically beginning in young adulthood, patients suffer hallucinations, delusions, and disordered thinking. There is no cure.

The first generation of antipsychotics, such as Thorazine and Haldol, proved quite effective in reducing the intensity of symptoms. But the drugs had side effects resembling Parkinson's disease: tremor, rigid muscles, and abnormal or restless movements.

More than a decade ago, the second generation of atypical antipsychotic drugs was introduced. They're much less likely to cause Parkinson's-like side effects, although they do carry an increased risk of extreme weight gain and type 2 diabetes.

Most of the second-generation antipsychotics — such as Clozaril, Risperdal, Zyprexa, Seroquel, Geodon, and Abilify — come only in pill form.

The only second-generation injectable drug for schizophrenia, Risperdal Consta, has to be given every two weeks.

Compliance an Issue

Because it only requires going to the doctor once a month, injectable paliperidone palmitate may make it more likely a person will comply with his or her treatment plan, doctors say.

"Using an injectable agent ensures the drug gets into the blood. You're not relying on the patient to remember to take a pill every day," Hough says.

Temple University's David Baron, DO, chairman of the committee that chose which studies to highlight at the meeting, says that compliance is a huge issue in schizophrenia — "conservatively affecting 50% to 60% of patients."

"Some patients have trouble swallowing pills. And in inpatient settings, some 'cheek' or spit out their pills. That's why we need injectables. [This will be] one more tool in the toolbox."

"Paliperidone palmitate solves a disadvantage of Consta — patients having to come in monthly for a [psychiatric] consult but every two weeks for an injection," says Donald Goff, MD, director of the schizophrenia program at Massachusetts General Hospital.

But, he adds, injectable antipsychotics have been generally slow to catch on in the U.S.

Baron says that's because oral medications can be stopped quickly if there are side effects or if they're not working. With injectable drugs, "once they're in, they're in."

SOURCES:American Psychiatric Association 2008 Annual Meeting, Washington, D.C., May 3-8, 2008. David Hough, MD, consultant, Johnson & Johnson; Psychiatric Services of Princeton, Princeton, N.J. David Baron, DO; chairman, APA program committee; Temple University. Donald Goff, MD, director of the schizophrenia program, Massachusetts General Hospital.

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