Clinical Trial Findings

The effectiveness of Risperdal Consta was established in a 12-week, placebo-controlled study in 400 adults with schizophrenia both in inpatient and outpatient settings. Efficacy was assessed using the Positive and Negative Syndrome Scale (PANSS), a common measure of the total severity of positive symptoms (psychological disturbances "added" as a result of the disorder, such as hallucinations, delusions, suspiciousness and paranoia) and negative symptoms (normal functioning the patient has "lost," resulting in lack of initiative and loss of normal enjoyment).

Patients who received Risperdal Consta experienced significantly greater improvements in both positive and negative symptoms than did those who were administered placebo:
Forty-seven percent of patients treated with a 25 mg dosage of Risperdal Consta experienced clinical improvement compared to 17 percent of those who received placebo. Clinical improvement is defined as 20 percent or more reduction in PANSS total score.

The most common side effects experienced by patients taking Risperdal Consta during the 12-week study were headache, agitation, psychosis, insomnia, dizziness, rhinitis and pain. Overall, similar proportions of patients reported adverse events in the placebo and Risperdal Consta groups (80 percent vs. 83 percent), and serious adverse events were more common in the placebo group (23.5 percent) than in the Risperdal Consta groups (13 percent in the 25 mg group and 14 percent in the 50 mg group). The incidence of spontaneously reported adverse events related to extrapyramidal symptoms (reversible movement disorders or muscle disturbances such as restlessness, tremors and muscle stiffness) in the 25 mg Risperdal Consta group was similar to placebo (10 percent vs. 13 percent). The rate of adverse events related to extrapyramidal symptoms in the 50 mg group was 24 percent. Treatment was discontinued due to side effects by 12 percent of patients receiving Risperdal Consta (37/302) and 12 percent of patients (12/98) receiving placebo.

As with oral Risperdal,** patients taking Risperdal Consta experienced low weight gain over 12 weeks (0.5 kg [1.1 lbs.] in the 25 mg group and 1.2 kg [2.6 lbs.] in the 50 mg group.) In addition, patients reported that injection-site pain was low at the first injection and decreased further as the study progressed. On a 100-point rating scale, where 0 represented no pain and 100 represented unbearable pain, patients receiving the 25 mg dose reported pain at a level of nine following their sixth dose. Further, in all groups, less then 5 percent of patients experienced redness, swelling or indurations following injection.