Paliperidone Palmitate and Risperidone Long-acting Injectable in Subjects with Schizophrenia Recently Treated with Oral Risperidone or Other Oral Antipsychotics

Background: This post hoc subgroup analysis of a randomized, double-blind trial evaluated the response to treatment with two long-acting injectable atypical antipsychotics, ie, paliperidone palmitate and risperidone long-acting injectable (RLAI), in subjects with schizophrenia experiencing clinically significant symptoms despite recent treatment with oral risperidone only or other oral antipsychotics.

Methods: Adult subjects were eligible for the 13-week, double-blind, double-dummy trial (NCT00589914) if they had an established diagnosis of schizophrenia for at least one year and a Positive and Negative Syndrome Scale (PANSS) total score of 60-120 inclusive at screening. Subjects received either paliperidone palmitate (234 mg, day 1; 156 mg, day 8; then once-monthly flexible dosing) or RLAI (25-50 mg biweekly, with oral risperidone supplementation on days 1-28), plus matched placebo injections/tablets.

Results: This post hoc analysis reports data on 747 subjects who, within 2 weeks of starting double-blind study medication, had reportedly received oral risperidone only (paliperidone palmitate group, n = 126; RLAI group, n = 107), other oral antipsychotics (paliperidone palmitate group, n = 199; RLAI group, n = 203), or no antipsychotic (paliperidone palmitate group, n = 56; RLAI group, n = 56). Mean PANSS total scores improved significantly at end point across all subgroups (mean change from baseline ranged from -17.5 to -19.5, all P < 0.0001). Clinical Global Impression-Severity and Personal and Social Performance scale measures also significantly improved from baseline (all P < 0.0001).

Conclusion: Treatment with paliperidone palmitate or RLAI resulted in a significant reduction in the symptoms of schizophrenia irrespective of previous recent treatment with oral risperidone only or other oral antipsychotics. For subjects who had previously received oral risperidone only, the difference in formulation was the main change in the intervention because the molecule delivered remained the same or similar. These data support the contribution of a long-acting formulation to improving the treatment response and suggest that nonadherence may be a significant contributor to inadequate efficacy of oral formulations in subjects with schizophrenia.