Tolerability of initiation doses of once-monthly paliperidone palmitate in patients with recently diagnosed schizophrenia in an acute treatment trial

Objective: To examine the tolerability of the recommended initiation doses for once-monthly injectable paliperidone palmitate in patients who have recently been diagnosed with schizophrenia and for whom high doses may pose tolerability concerns. Methods: A post hoc analysis from a 13-week double-blind study of patients with schizophrenia randomized 1: 1: 1: 1 to placebo or paliperidone palmitate at 25, 100, or 150mg equivalents (mg eq) of paliperidone (corresponding to 39, 156, or 234mg respectively). This analysis focused on the recently diagnosed subgroup (<= 5 years; N = 146) who received the recommended initiation dosage of paliperidone palmitate [150mgeq on day 1 (n = 109) followed by 100mgeq on day 8 (n = 39)] or placebo (n = 37). Adverse events (AEs), reported in >= 2% of patients receiving paliperidone palmitate during days 1-7 or >= 5% during days 8-36, and in a higher percentage of patients receiving paliperidone palmitate than placebo, were identified. AE relative risks (RRs) and 95% confidence intervals (CIs) were determined. A RR was considered potentially significant when its 95% CI did not include 1. Results: Overall, day 1-7 AE rates were 37.6% (41 of 109) and 29.7% (11 of 37) with paliperidone palmitate and placebo respectively; injection site pain (5.5% versus 2.7%, RR 2.0; 95% CI 0.25 to 16.37), agitation (4.6% versus 2.7%; RR 1.7; 95% CI 0.21 to 14.06), and headache (3.7% versus 0.0%; RR 3.1; 95% CI 0.17 to 56.41) met the >= 2% criteria. Day 8-36 AE rates were 41.0% (16 of 39) and 37.8% (14 of 37) with paliperidone palmitate and placebo respectively; anxiety (5.1% versus 0.0%; RR 4.8; 95% CI 0.24 to 95.76) met the >= 5% criteria. Key limitations were that some patients may have been ill for a significant time before formal diagnosis and that the number of patients is low in this subgroup, limiting the ability to detect statistical significance for AE RRs. Conclusions: Paliperidone palmitate initiation doses (150mgeq day 1, 100mgeq day 8) were tolerated in this subgroup of patients who were recently diagnosed with schizophrenia, with no unexpected findings. Although the same size was small, these data identified AEs that may be encountered during the week and month after initiation dosing. These findings may assist clinicians when paliperidone palmitate is considered an appropriate treatment choice for these patients.