Risperidone(Drug information on risperidone) (Risperdal) and olanzapine(Drug information on olanzapine) (Zyprexa) were directly compared for several populations in studies reported at the 41st annual NCDEU Meeting of the National Institute of Mental Health in Phoenix, May 28-31.
In a double-blind study sponsored by risperidone manufacturer Janssen Pharmaceutica, 377 patients with schizophrenia or schizoaffective disorder were randomly assigned to receive eight weeks of treatment with either risperidone 2 mg to 6 mg daily (mean dose 4.8 mg) or 5 mg to 20 mg of olanzapine (mean dose 12.4 mg). The groups were similar in the number of patients who dropped from the study and in the number experiencing extrapyramidal side effects (EPS), as well as in the severity of their EPS. The researchers reported greater improvement with risperidone on the Positive and Negative Syndrome Scale (PANSS) anxiety/depression cluster and the depression and grandiosity items, but they found no significant differences between groups on individual factors.
In another Janssen-sponsored study, 176 elderly patients with schizophrenia were treated with either 1 mg to 3 mg of risperidone daily (mean 2 mg) or 5 mg to 20 mg olanzapine (mean 10 mg). While there was greater reduction in PANSS scores with risperidone at study midpoint, there were no significant between-group differences at eight weeks on this or the secondary efficacy measures, and the groups had a similar incidence of common adverse events.
In an assessment of the level of functioning of 30 patients with schizophrenia receiving eight weeks of treatment with either risperidone or olanzapine, researchers at University of California, San Diego, reported comparable improvement, measured with the Scale of Functioning (SOF). The SOF total scores increased 4.7% for 15 patients on risperidone and 6.5% for those on olanzapine, although the final analysis did not significantly differentiate the groups.
Both olanzapine and risperidone, as well as haloperidol(Drug information on haloperidol) (Haldol), appeared less effective than clozapine(Drug information on clozapine) (Clozaril) in specifically reducing hostility symptoms in 157 treatment-resistant patients, in a study conducted by researchers at the Nathan Kline Institute at New York University and others. Patients were randomly assigned to 14 weeks of treatment with one of the four agents. The researchers reported that patients receiving clozapine evidenced greater improvement on the PANSS hostility item and that this difference was independent of antipsychotic effect. Neither risperidone nor olanzapine showed superiority over haloperidol on this measure.
An additional comparison of olanzapine and risperidone with a traditional neuroleptic was conducted in a naturalistic setting by University of Pittsburgh researchers. They commented that although the efficacy of atypical antipsychotics has been well-established, "the comparative effectiveness between agents is less clear. We set out to evaluate treatment effectiveness of olanzapine, risperidone and the conventional agent, perphenazine(Drug information on perphenazine) [Etrafon, Triavil, Trilafon]."
The researchers conducted a retrospective review of 386 patients discharged on one of these agents between January 1997 and June 1998. They found no statistical differences in one-year readmission rates between the groups nor in time to first admission. Other measures of drug effectiveness such as functioning were not applied nor were measures of how the drugs were tolerated.
Olanzapine was also compared to ziprasidone(Drug information on ziprasidone) (Geodon) in a study sponsored by ziprasidone manufacturer Pfizer Inc. In the six-week assessment, 268 patients were randomized to receive either 5 mg to 15 mg olanzapine daily or 40 mg to 80 mg ziprasidone twice daily. The groups demonstrated comparable improvement on efficacy measures, as well as on movement disorder ratings. Although there were no significant differences on these measures, the researchers noted differences favoring ziprasidone on "health parameters" of weight gain and cholesterol level increase.
Addressing the issue of weight gain, Eli Lilly and Company researchers reported administering the histamine H2 blocker nizatidine(Drug information on nizatidine) (Axiol), a putative appetite suppressant, in combination with olanzapine in an effort to mitigate associated weight gain. In comparison to an olanzapine and placebo combination, there was significantly less weight gain in patients receiving 300 mg nizatidine twice daily, but not in those receiving 150 mg. In the 16-week treatment period, olanzapine with placebo was associated with an average body weight increase of 12.15 lbs; patients receiving nizatidine 150 mg twice daily with olanzapine gained an average of 9.72 lbs, and those receiving 300 mg twice daily with olanzapine gained 6.08 lbs.