FRIDAY, May 9, 2003 (HealthDayNews) -- Newer drugs used to treat psychosis are thought to have fewer side effects, but now a new study challenges that thinking.
Writing in the May 10 issue of The Lancet, researchers say older, low-potency drugs might not cause more neurological side effects -- such as tremors -- than the newer drugs after all. They arrived at that conclusion after analyzing 31 existing studies involving 2,320 patients.
Of the newer generation of drugs, they found only clozapine (Clozaril) was associated with significantly fewer neurological side effects and higher effectiveness. But chlorpromazine (Thorazine), when given at less than 600 milligrams a day, had no higher risk of neurological side effects than the newer generation of drugs, the research team concludes.
Their findings do not yet warrant a recommendation to change treatment, they say, but there is a need to study the concept further.
Antipsychotic drugs are a class of medicines used to treat psychoses such as schizophrenia and other emotional and mental conditions. The drugs are widely used to treat older persons with behavioral symptoms. Drugs that came on the market in the last decade are considered newer generation treatments.
"The new generation drugs have been heavily marketed by the pharmaceutical industry, which have claimed that the new drugs are superior to the old ones," says study co-author Kristian Wahlbeck, with STAKES National Research and Development Centre for Welfare and Health in Helsinki, Finland.
"The consensus among researchers in the field has so far been that the new drugs show a modest benefit in decreasing symptoms of psychosis and that the main advantage of the new drugs is the lower propensity to cause motor adverse effects. We now challenge this view, and claim that if the conventional drugs are given in sufficient low doses, there is no superiority of the new drugs regarding motor adverse effects."
Besides tremors, among the neuromotor side effects of antipsychotic drugs are tardive dyskinesia, in which there are involuntary body movements, and restlessness marked by muscle quivering or an inability to sit down. Some side effects are reversible, but others may not be.
"I am pretty sure that our report will ignite a vivid debate," Wahlbeck says. Yet, she offers caveats: "Our results are based on secondary analysis of the data, and caution has to be taken due to the limited amount of available data. We had no access to individual patient data."
She says the conclusions do not warrant a general recommendation to use the older drugs, partly because advantages of the newer drugs have been shown in a number of other areas besides the aspect of neurological side effects.
This new analysis is a bit different from previous studies, says Deborah Antai-Otong, a clinical nurse specialist and nurse practitioner who has authored several papers and book chapters on the topic of antipsychotic medications.
"They looked at [studies] that compared new generation [antipsychotics] with older generation, low-potency ones," says Antai-Otong, who's with the VA North Texas Health Care System in Dallas. Other studies have compared the new generation drugs with high-potency older drugs, she says.
As for advice for those with psychoses or their caretakers, Wahlbeck says consulting the treating physician is the best idea. "There isn't enough data to support the view that all patients with psychoses should receive the new antipsychotics. Conventionals in low dose may be as safe as the new ones and may even lack some of the adverse effects of certain new drugs."
Deciding which type of antipsychotic drug is best for a patient is not easy, Antai-Otong agrees. "There are those who have been on low doses of older drugs for a long time, and they may be fine." But it's known that the longer someone is on an antipsychotic, the higher the risk of side effects.
More information
For more information on schizophrenia, see the National Institute of Mental Health. For details on antipsychotic drugs, see Hendrick Health.
