May 11, 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,
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
The most common side effects were weight gain and stomach flu.
The findings were presented at the annual meeting of the American
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."