Study of Pharmacokinetics, Safety, Efficacy, and Tolerability of Memantine in Children With Autism

An Open-label (Part One) and a Randomized, Double-blind, Placebo-Controlled (Part Two) Study of the Pharmacokinetics, Safety, Efficacy, and Tolerability of Memantine in Pediatric Patients With Autism

The purpose of this study is to investigate the safety and efficacy of memantine extended release, as well as its extent of absorption in pediatric patients with autism.

This is a multicenter, two-part study in pediatric (ages 6 to 18 years) patients diagnosed with autism. Patients participating in Part One will receive a single open-label dose of memantine. Blood samples for pharmacokinetic analysis will be collected. Part Two is a randomized, double-blind, placebo-controlled 12-week efficacy and safety study evaluating change in all core domains (social interactions, communication, and restricted interests and repetitive behaviors) of autism. In the Forest autism trials conducted in children ages 6-12, dosing with an extended release formulation of memantine was weight-based. These weight based dose limits were selected to ensure exposure in terms of area under the curve (AUC) was less than the predefined limit of 2100 ng∙h/mL that represented a 10-fold lower exposure than observed at the NOAEL (No observed adverse effect level) of 15 mg/kg/day in juvenile rats. The weight-based dose limits in these studies were as follows: Group A: ≥ 60 kg; max 15 mg/day Group B: 40-59 kg; max 9 mg/day Group C: 20-39 kg; max 6 mg/day Group D: < 20 kg; max 3 mg/day

Memantine - 3mg and 6mg capsules, dose ranging 3 - 18 mg/day in 4 weight groups, administered orally.

Area under the plasma concentration vs. time curve (AUC) for memantine, as measured in units of nanogram x hours per milliliter.

Baseline to 144 hours. Measurements were taken 0 (predose), 4, 8, 24, 30, 48, 96 and 144 hours post-dose

The Social Responsiveness Scale (SRS) is a 65-item informant-rated assessment, ranging from 0 (no impairment) to 195 (severe social impairment). Each item is associated with 1 of 5 subscales (social awareness, social cognition, social communication, social motivation and autistic mannerisms). Each item is rated on a 4-point scale from 1 (not true) to 4 (almost always true). The scores are then transposed to a scale from 0 to 3 and scores are summed within each of the 5 subscales. A higher score indicates greater severity of social impairment.

The Core Autism Treatment Scale-Improvement (CATS-I) is based on rating 14 items from 1 (very much improved) to 7 (very much worse) with a total score ranging from 14 (improved) to 98 (worsened). The Core Autism Treatment Scale-Improvement (CATS-I) is designed to utilize a comparison between pretreatment ratings of Core Autism Treatment Scale-Severity (CATS-S) and ratings of improvement after start of therapy (CATS-I). Both parts of the CATS contain 14 items testing for social interaction (items 1-9) and communication (items 10-14). Each of these items is rated from 1 (indicating most benign) to 7 (indicating most severe).

The Core Autism Treatment Scale-Improvement (CATS-I) Social Interaction Subscale is based on rating 9 items from 1 (very much improved) to 7 (very much worse) with a total score ranging from 9 (improved) to 63 (worsened). The Core Autism Treatment Scale-Improvement (CATS-I) is designed to utilize a comparison between pretreatment ratings of Core Autism Treatment Scale-Severity (CATS-S) and ratings of improvement after start of therapy (CATS-I). Both parts of the CATS contain 14 items testing for social interaction (items 1-9) and communication (items 10-14). Each of these items is rated from 1 (indicating most benign) to 7 (indicating most severe).

The Core Autism Treatment Scale-Improvement (CATS-I) Communication Subscale is based on rating 5 items from 1 (very much improved) to 7 (very much worse) with a total score ranging from 5 (improved) to 35 (worsened). The Core Autism Treatment Scale-Improvement (CATS-I) is designed to utilize a comparison between pretreatment ratings of Core Autism Treatment Scale-Severity (CATS-S) and ratings of improvement after start of therapy (CATS-I). Both parts of the CATS contain 14 items testing for social interaction (items 1-9) and communication (items 10-14). Each of these items is rated from 1 (indicating most benign) to 7 (indicating most severe).

The Children's Communication Checklist-2 (CCC-2) Speech Subscale consists of 7 items rated from 0 (less than once a week or never) to 3 (several times [more than twice] a day or always), with a total raw score of 0 (mildest) to 21 (most severe). The Children's Communication Checklist-2 (CCC-2) is a validated, norm-referenced, informant-rated scale that evaluates difficulties children may have (across 10 different subscales, consisting of 7 items each) that affect communication (items 1-50), as well as strengths that children may demonstrate when communicating with others (items 51-70).

The Children's Communication Checklist-2 (CCC-2) Syntax Subscale consists of 7 items rated from 0 (less than once a week or never) to 3 (several times [more than twice] a day or always), with a total raw score of 0 (mildest) to 21 (most severe). The Children's Communication Checklist-2 (CCC-2) is a validated, norm-referenced, informant-rated scale that evaluates difficulties children may have (across 10 different subscales, consisting of 7 items each) that affect communication (items 1-50), as well as strengths that children may demonstrate when communicating with others (items 51-70).

The Children's Communication Checklist-2 (CCC-2) Semantics Subscale consists of 7 items rated from 0 (less than once a week or never) to 3 (several times [more than twice] a day or always), with a total raw score of 0 (mildest) to 21 (most severe). The Children's Communication Checklist-2 (CCC-2) is a validated, norm-referenced, informant-rated scale that evaluates difficulties children may have (across 10 different subscales, consisting of 7 items each) that affect communication (items 1-50), as well as strengths that children may demonstrate when communicating with others (items 51-70).

The Children's Communication Checklist-2 (CCC-2) Coherence Subscale consists of 7 items rated from 0 (less than once a week or never) to 3 (several times [more than twice] a day or always), with a total raw score of 0 (mildest) to 21 (most severe). The Children's Communication Checklist-2 (CCC-2) is a validated, norm-referenced, informant-rated scale that evaluates difficulties children may have (across 10 different subscales, consisting of 7 items each) that affect communication (items 1-50), as well as strengths that children may demonstrate when communicating with others (items 51-70).

The Children's Communication Checklist-2 (CCC-2) Initiation Subscale consists of 7 items rated from 0 (less than once a week or never) to 3 (several times [more than twice] a day or always), with a total raw score of 0 (mildest) to 21 (most severe). The Children's Communication Checklist-2 (CCC-2) is a validated, norm-referenced, informant-rated scale that evaluates difficulties children may have (across 10 different subscales, consisting of 7 items each) that affect communication (items 1-50), as well as strengths that children may demonstrate when communicating with others (items 51-70).

The Children's Communication Checklist-2 (CCC-2) Scripted Language Subscale consists of 7 items rated from 0 (less than once a week or never) to 3 (several times [more than twice] a day or always), with a total raw score of 0 (mildest) to 21 (most severe). The Children's Communication Checklist-2 (CCC-2) is a validated, norm-referenced, informant-rated scale that evaluates difficulties children may have (across 10 different subscales, consisting of 7 items each) that affect communication (items 1-50), as well as strengths that children may demonstrate when communicating with others (items 51-70).

The Children's Communication Checklist-2 (CCC-2) Context Subscale consists of 7 items rated from 0 (less than once a week or never) to 3 (several times [more than twice] a day or always), with a total raw score of 0 (mildest) to 21 (most severe). The Children's Communication Checklist-2 (CCC-2) is a validated, norm-referenced, informant-rated scale that evaluates difficulties children may have (across 10 different subscales, consisting of 7 items each) that affect communication (items 1-50), as well as strengths that children may demonstrate when communicating with others (items 51-70).

The Children's Communication Checklist-2 (CCC-2) Nonverbal Communication Subscale consists of 7 items rated from 0 (less than once a week or never) to 3 (several times [more than twice] a day or always), with a total raw score of 0 (mildest) to 21 (most severe). The Children's Communication Checklist-2 (CCC-2) is a validated, norm-referenced, informant-rated scale that evaluates difficulties children may have (across 10 different subscales, consisting of 7 items each) that affect communication (items 1-50), as well as strengths that children may demonstrate when communicating with others (items 51-70).

The Children's Communication Checklist-2 (CCC-2) Social Relations Subscale consists of 7 items rated from 0 (less than once a week or never) to 3 (several times [more than twice] a day or always), with a total raw score of 0 (mildest) to 21 (most severe). The Children's Communication Checklist-2 (CCC-2) is a validated, norm-referenced, informant-rated scale that evaluates difficulties children may have (across 10 different subscales, consisting of 7 items each) that affect communication (items 1-50), as well as strengths that children may demonstrate when communicating with others (items 51-70).

The Children's Communication Checklist-2 (CCC-2) Interests Subscale consists of 7 items rated from 0 (less than once a week or never) to 3 (several times [more than twice] a day or always), with a total raw score of 0 (mildest) to 21 (most severe). The Children's Communication Checklist-2 (CCC-2) is a validated, norm-referenced, informant-rated scale that evaluates difficulties children may have (across 10 different subscales, consisting of 7 items each) that affect communication (items 1-50), as well as strengths that children may demonstrate when communicating with others (items 51-70).

Inclusion Criteria: Males or females ages 6 to 12 years Diagnosis of autistic disorder, according to DSM-IV-TR using Autism Diagnostic Interview-Revised and Autism Diagnostic Observation Schedule (modules 2 & 3). A knowledgeable caregiver capable of providing reliable information about the patient's condition, able to attend all clinic visits with the patient Patients over age 12, only if they completed Study MEM-PK-21 Exclusion Criteria: Medical history of active epilepsy/seizure disorder except simple febrile seizures Participation in any other clinical investigation using an experimental drug within 30 days of the start of this study

Brignell A, Marraffa C, Williams K, May T. Memantine for autism spectrum disorder. Cochrane Database Syst Rev. 2022 Aug 25;8(8):CD013845. doi: 10.1002/14651858.CD013845.pub2.