A head-to-head comparison of five schizophrenia drugs found that most newer treatments are no better than an older generic drug, despite their higher costs, a U.S. study released on Monday showed.
The lone exception, Eli Lilly and Co.’s Zyprexa, may be better than the other medicines but users experienced dramatic weight gain and developed a higher risk of diabetes, the study concluded. The drug is also the most expensive.
The research, financed by the National Institute of Mental Health and to be published in Thursday’s New England Journal of Medicine, indicates “substantial limitations in the effectiveness of the drugs,” said the team led by Jeffrey Lieberman of Columbia University.
But it should also help doctors choose the best therapy for the 3.2 million Americans suffering from schizophrenia, the tough-to-treat mental illness marked by delusions, hallucinations and scrambled thinking.
Because the effectiveness of a drug can vary from person to person, side effects can force patients to stop taking them or can cause doctors to switch between medicines and alter dosages to find the best, most tolerable treatment.
The study used the amount of time patients stayed on a drug to help gauge its effectiveness. In all, 74 percent of the 1,432 volunteers at 57 study sites stopped taking the medication they were originally assigned.
Only the schizophrenics taking Zyprexa, also known as olanzapine, stuck with it significantly longer than the other four. But even 64 percent stopped taking it after 18 months.
The discontinuation rate was higher among the other four drugs: Seroquel (quetiapine) from AstraZeneca Plc; Risperdal (risperidone) from Janssen Pharmaceutica, a wholly owned unit of Johnson & Johnson; Geodon (ziprasidone) from Pfizer Inc., and perphenazine, which has been around since the 1950s and is available in generic form.
The researchers also found that people on Zyprexa were less likely to be hospitalized for a psychotic relapse.
While 15 to 20 percent of patients taking the other drugs ended up in hospital because their condition worsened, the rate was 11 percent for recipients of the Lilly drug.
It said one surprise was that perphenazine’s side effects such as tremor, rigidity, stiff movements and muscle restlessness were not as common as expected. Patients tolerated it just as well as some of the newer drugs, and it was no less effective. And it was far cheaper.
At the average doses used in the study, a month’s supply of perphenazine capsules costs about $50 -- compared with roughly $390 for Geodon, $425 for Risperdal, $475 for Seroquel, and $660 for Zyprexa. Physicians determined the actual dose each patient received.
Weight gain among patients on Zyprexa was significantly higher. Patients on the drug typically added two pounds (0.97 kg) a month. With two of the other drugs, patients gained up to half a pound (0.23 kg) and with the other two, they lost a small amount of weight every month.
And while all five drugs raised blood sugar levels, the gains were more than twice as high for Zyprexa compared to levels in volunteers treated by the other medicines.
Lieberman said doctors must weigh the pros and cons of each drug carefully because “what works for one person may not work for another.”
