Onset of efficacy with acute long-acting injectable paliperidone palmitate treatment in markedly to severely ill patients with schizophrenia: post hoc analysis of a randomized, double-blind clinical trial

BACKGROUND This post hoc analysis (trial registration: ClinicalTrials.gov NCT00590577) assessed onset of efficacy and tolerability of acute treatment with once-monthly paliperidone palmitate (PP), a long-acting atypical antipsychotic initiated by day 1 and day 8 injections, in a markedly to severely ill schizophrenia population. METHODS Subjects entering the 13-week, double-blind trial were randomized to PP (39, 156, or 234 mg [25, 100, and 150 mg eq of paliperidone, respectively]) or placebo. This subgroup analysis included those with a baseline Clinical Global Impressions-Severity (CGI-S) score indicating marked to severe illness. PP subjects received a 234-mg day 1 injection (deltoid), followed by their assigned dose on day 8 and monthly thereafter (deltoid or gluteal). Thus, data for PP groups were pooled for days 4 and 8. Measures included Positive and Negative Syndrome Scale (PANSS), CGI-S, Personal and Social Performance (PSP), and adverse events (AEs). Analysis of covariance (ANCOVA) and last-observation-carried-forward (LOCF) methodologies, without multiplicity adjustments, were used to assess changes in continuous measures. Onset of efficacy was defined as the first time point a treatment group showed significant PANSS improvement (assessed days 4, 8, 22, 36, 64, and 92) versus placebo, which was maintained through end point. RESULTS A total of 312 subjects met inclusion criterion for this subgroup analysis. After the day 1 injection, mean PANSS total scores improved significantly with PP (all received 234 mg) versus placebo at day 4 (P = 0.012) and day 8 (P = 0.007). After the day 8 injection, a significant PANSS improvement persisted at all subsequent time points in the 234-mg group versus placebo (P < 0.05). PANSS improvements were greater from day 36 through end point in the 156-mg group (P < 0.05) and only at end point in the 39-mg group (P < 0.05). CGI-S and PSP scores improved significantly in the 234-mg and 156-mg PP groups versus placebo at end point (P < 0.05 for both, respectively); improvement in the 39-mg group was not significant. The most common AEs for PP-treated subjects (≥10%, any treatment group) were headache, insomnia, schizophrenia exacerbation, injection site pain, and agitation. CONCLUSIONS In this markedly to severely ill population, acute treatment with 234 mg PP improved psychotic symptoms compared with placebo by day 4. After subsequent injections, observed improvements are suggestive of a dose-dependent effect. No unexpected tolerability findings were noted.