Cariprazine in Pediatric Patients with Autism Spectrum Disorder: Results of a Pharmacokinetic, Safety and Tolerability Study

Abstract

Objective: Cariprazine is a dopamine D₃-preferring D₃/D₂ and serotonin 5-HT_1A receptor partial agonist approved to treat adults with schizophrenia and manic/mixed or depressive episodes associated with bipolar I disorder. This study, which is the first to evaluate cariprazine in pediatric patients with autism spectrum disorder (ASD) (including children 5-9 years of age) using an oral solution formulation, evaluated the safety, tolerability, pharmacokinetics (PK), and exploratory efficacy of cariprazine and its two major active metabolites, desmethyl cariprazine (DCAR) and didesmethyl cariprazine (DDCAR). Methods: This clinical pharmacology, open-label, multiple-dose study enrolled 25 pediatric patients from 5 to 17 years of age, who met the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition criteria for ASD. All patients began treatment with cariprazine 0.5 mg once daily (QD) and underwent a titration over 7 days to maintenance doses of 1.5 or 3 mg QD for patients 13-17 years of age at Screening, 0.75 or 1.5 mg QD for patients 10-12 years of age at Screening, and 0.5 or 1.5 mg QD for patients 5-9 years of age at Screening. After 6 weeks total of dosing, there was a 6-week follow-up period. Study assessments included adverse events (AEs), safety parameters, noncompartmental PK parameters, and exploratory efficacy assessments, including the Aberrant Behavior Checklist-Irritability Subscale (ABC-I), Clinical Global Impressions (CGI-S), Caregiver Global Impressions (CgGI-S), Children's Yale-Brown Obsessive Compulsiveness Scale Modified for ASD (CYBOCS-ASD), Social Responsiveness Scale (SRS), and Vineland Adaptive Behavior Scale (VABS-III). Results: All AEs were mild or moderate in severity. Most frequent treatment-emergent adverse events (TEAEs) were increased weight, increased alanine aminotransferase, increased appetite, dizziness, agitation, and nasal congestion. Increases in weight were not considered clinically meaningful. Two subjects reported extrapyramidal symptom-related TEAEs that resolved without leading to discontinuation. Dose-normalized exposures of all analytes were modestly higher in pediatric patients from 5 to 9 years of age when compared to older patients. Consistent with previous studies, at steady state, the rank of exposure in plasma was DDCAR > cariprazine > DCAR. There was numerical improvement on all exploratory endpoints (ABC-I, CGI-S, CgGI-S, CYBOCS-ASD, SRS, and VABS-III). Conclusions: PK of cariprazine and its metabolites were characterized in pediatric patients with ASD at doses up to 3 mg QD (13-17 years) and 1.5 mg QD (5-12 years). Caripazine treatment was generally well tolerated and results from this study will inform the selection of appropriate pediatric doses for subsequent studies.

Keywords: atypical antipsychotic; autism spectrum disorder; cariprazine; pediatric; pharmacokinetic.

FIG. 1.

Plasma concentrations of cariprazine and metabolites after dosing on day 42.

FIG. 2.

Dose proportionality assessment for steady-state PK parameters of cariprazine and metabolites. Dose proportionality assessment for steady-state pharmacokinetic parameters of cariprazine and metabolites. Pediatric patients 13–17 years old received 1.5 or 3 mg QD. Pediatric patients 10–12 years old received 0.75 or 1.5 mg QD. Pediatric patients 5–9 years old received 0.5 or 1.5 mg QD. CAR, cariprazine; DCAR, desmethyl cariprazine; DDCAR, didesmethyl cariprazine; QD, once daily.

FIG. 3.

Allometric relationship of oral clearance of cariprazine and pediatric body weight. Allometric relationship between oral clearance of cariprazine (CL_ss/F) and pediatric body weight. $CL∕F_{child}=21.5L∕h\times {\left(\frac{B{W}_{child}}{79kg}\right)}^{\theta }$; the optimized allometric exponent ($\theta =0.15$, blue line) is compared against the coventional allometric exponent ($\theta =0.75$, orange line).

FIG. 4.

ABC-I scores over 6 weeks of treatment. ABC-I, Aberrant Behavior Checklist-Irritability Subscale.