Patients with symptomatically stable schizophrenia, including young adults whose initial disease had been stabilized with other medications, had additional improvement in symptom control when shifted to long-acting risperidone, according to presentations at the annual meeting of the American Psychiatric Association. The injectable formulation is the first and only long-acting atypical antipsychotic to date to be approved for use in the US.

The first data set to be presented reflected results for 119 adult patients treated for 6 months in a European trial. Symptoms were evaluated with use of the Clinical Global Impression-Severity (CGI-S) scale at baseline and at endpoint, classifying patients as "not ill," "very mild" or "mild" up to "severely ill." At endpoint, a significant improvement was seen in scores, with 14 percent considered "not ill" compared with only 2 percent at baseline. In addition, approximately 22 percent were considered "very mild" (versus approximately 11 percent, baseline) and approximately 16 percent were considered "mild" (versus approximately 21 percent, baseline). Baseline medications include various oral antipsychotic agents.

At endpoint, the mean total efficacy measure, the Positive and Negative Syndrome Scale (PANSS), score also improved significantly. Thirty-one percent of the already stable patients showed an improvement in total PANSS scores of at least 20 percent compared with baseline -- regarded as a clinically relevant response among patients with a stable baseline condition.

"Many patients achieve symptom stability with available medications," said Wim J. Arnoldussen, M.D., study presenter. "In our study, we found the number of patients treated with Risperdal Consta categorized as 'not ill' or 'very mild' nearly doubled by the end of the study."

The second data set reflected analysis of 110 young adult patients (mean age, 23 years) enrolled in a 50-week, open-label trial. As with the European trial participants, these patients were symptomatically stable after treatment with various oral antipsychotic agents and then transitioned to the long-acting injectable drug.

Patients' mean PANSS total scores significantly improved from an already mild score of 67 at baseline to 57 at endpoint. Scores on each symptom domain also decreased significantly at endpoint. These domains included positive and negative symptoms, disorganized thoughts, anxiety/depression, and uncontrolled hostility/excitement.

The overall symptom severity of patients was assessed by the Clinical Global Impression-Severity (CGI-S) scale. The number of young adult patients with CGI-S ratings of "not ill," "very mild," and "mild" increased significantly from 39 percent at baseline to 60 percent at the endpoint.

Improvements also were seen in patients' ratings of extrapyramidal symptoms using the Extrapyramidal Symptom Rating Scale (ESRS). Pain associated with injection was low at baseline and continued to decrease during the trial. The most common adverse events in patients given the injectable long-acting formulation were insomnia (27 percent), psychosis (22 percent), anxiety (21 percent), depression (17 percent), and rhinitis (15 percent).

John Kane, MD, presenter, said "We've known for some time that early and consistent intervention in schizophrenia can improve patients' long-term outcomes, such as hospitalization. However, many early-stage patients discount the need for treatment, which ultimately may lead to relapse and hospitalization. This study suggests that consistent therapy with Risperdal Consta early in the course of the disease has real benefits in stable, young adult patients."