Development of a population pharmacokinetic model for the novel long-acting injectable antipsychotic risperidone ISM®.

AIMS: The aims of this study were to develop a population pharmacokinetic (PK) model for risperidone ISM® and to investigate the relationships between active moiety exposure, as described by apparent clearance (CL40), and several covariates using all data from five clinical studies. METHODS: A population PK model was developed using active moiety concentrations from a study in healthy volunteers and two studies in patients with schizophrenia. Data from a comparative bioavailability study in medically stable patients and a Phase III study in patients with acute exacerbation of schizophrenia were then incorporated, using empirical Bayesian feedback and model refinement in NONMEM. Finally, covariate analysis was performed on CL40. RESULTS: The final model adequately described the pharmacokinetics of 6288 active moiety concentrations in 17 healthy volunteers and 430 patients with schizophrenia. This one-compartment disposition model had a complex absorption process, combining a small amount immediately entering the central active moiety compartment, two first-order absorption processes and a combined zero-order and first order process, with first-order elimination from the central compartment. Significant covariates on CL40 were BMI and sex. Goodness-of-fit (GOF) plots and visual predictive checks (VPC) confirmed acceptable description of the data. CONCLUSIONS: The population PK model adequately described active moiety concentrations from five clinical studies after risperidone ISM® administration. Relationships between active moiety exposure and covariates were defined in order to facilitate simulations for future studies. The model showed that risperidone ISM® rapidly achieves therapeutic plasma levels within the first hours after the first injection that are maintained sustainedly throughout the whole dosing interval following once-monthly gluteal injections of 100 mg and 75 mg.

Efficacy and safety of once-monthly Risperidone ISM® in schizophrenic patients with an acute exacerbation.

To evaluate the efficacy and safety of Risperidone ISM® against placebo in patients with acute exacerbation of schizophrenia. A multicenter, randomized, double-blind, placebo-controlled study was conducted between June 2017 and December 2018 (NCT03160521). Eligible patients received once-monthly intramuscular injections of Risperidone ISM® (75 or 100 mg) or placebo for 12 weeks. The primary efficacy outcome was change in Positive and Negative Syndrome Scale (PANSS) total score from baseline to week 12. The key secondary efficacy outcome was change from baseline in Clinical Global Impressions-Severity of Illness scale (CGI-S) score. Altogether, 438 patients were randomized (1:1:1) and 390 included in the modified ITT efficacy set. The PANSS total score (mean difference, 95% CI) improved significantly from baseline to day 85 with Risperidone ISM® 75 and 100 mg, with placebo-adjusted differences of -13.0 (95% CI, -17.3 to -8.8); (p < 0.0001), and -13.3 (-17.6 to -8.9); (p < 0.0001), respectively. Significantly improved mean changes were also obtained for CGI-S score from baseline to day 85 for both doses of Risperidone ISM® compared with placebo -0.7 (-1.0 to -0.5); p < 0.0001, for both doses. The statistically significant improvement for both efficacy outcomes were observed as early as 8 days after first injection. The most frequently reported treatment-emergent adverse events were increased blood prolactin (7.8%), headache (7.3%), hyperprolactinemia (5%), and weight increase (4.8%). Neither new nor unexpected relevant safety information was recorded. Risperidone ISM® provided rapid and progressive reduction of symptoms in patients with acutely exacerbated schizophrenia without need of oral risperidone supplementation or loading doses. Both doses were safe and well tolerated.

A phase II study to evaluate the pharmacokinetics, safety, and tolerability of Risperidone ISM multiple intramuscular injections once every 4 weeks in patients with schizophrenia.

This study characterized the pharmacokinetics, safety, and tolerability of Risperidone ISM, a new long-acting intramuscular formulation, for monthly administration without oral supplementation. Patients with schizophrenia received multiple intramuscular injections of 75 mg in the gluteal or deltoid muscle at 28-day intervals. Of the 70 randomized patients, 67 received at least one dose of study medication. The mean Cmax of the active moiety was achieved 24-48 h (tmax) after each administration, regardless of injection site. They ranged over four consecutive doses from 39.6 to 53.2 and 54.1 to 61 ng/ml, when given in gluteal or deltoid muscle, respectively. Active moiety achieved therapeutic levels by 2 h after dose, and the levels were maintained throughout the 4-week dosing period. No significant changes across the study were observed on either Positive and Negative Syndrome Scale or Extrapyramidal Symptoms Scale. Overall, 63 (94%) patients experienced at least one treatment-emergent adverse event (TEAE). One serious TEAE (dystonia) was related to study treatment. The most frequently reported TEAEs were hyperprolactinaemia (57.7%) and injection site pain (32.8%). Risperidone ISM achieved therapeutic levels from the first hours after drug administration and provided a sustained release throughout the 4-week dosing period over multiple intramuscular injections and was found to be safe and well tolerated.

Phase I, open-label, randomized, parallel study to evaluate the pharmacokinetics, safety, and tolerability of one intramuscular injection of risperidone ISM at different dose strengths in patients with schizophrenia or schizoaffective disorder (PRISMA-1).

The aim of this study was to characterize the pharmacokinetics and to evaluate the safety of risperidone ISM in patients with schizophrenia or schizoaffective disorder after a single gluteal intramuscular injection at three different dose strengths (50, 75, and 100 mg). A total of 36 patients were randomized and blood samples were collected to measure the plasma concentrations. The pharmacokinetic of the active moiety was biphasic for all three dose groups, and the mean plasma concentration was 21.45, 24.60, and 29.68 ng/ml in the 50, 75, and 100 mg group, respectively, 24 h after dose administration; 22.81, 24.57, and 31.41 ng/ml in the 50, 75, and 100 mg group, respectively, 48 h after dose administration, and 12.26, 17.31, and 20.01 ng/ml in the 50, 75, and 100 mg group, respectively, 30 days after dose administration. Overall, 34 patients experienced at least one treatment-emergent adverse event (TEAE). Two patients experienced a serious TEAE and no deaths occurred. There were no extrapyramidal symptoms-related serious TEAEs and no significant changes in any Columbia Suicide Severity Rating Scale parameter were observed during the study. Risperidone ISM provided a sustained release of risperidone that achieved therapeutic plasma levels within the first day. Risperidone ISM was safe, well tolerated, and should be suitable for a 4-weekly administration without oral supplementation.