The utility of the irritability scale in Huntington's disease patients with evidence of irritability or aggression.

INTRODUCTION: Irritability, a common neuropsychiatric symptom in Huntington's disease (HD), lacks a standardized measurement. The Irritability Scale (IS), tailored for HD, has patient and informant versions, but variable interrater agreement has been reported frequently in previous studies. To enhance the clinical utility of the IS, this study aimed to identify the most reliable components estimating the underlying construct and develop a shortened version for time-limited contexts. METHODS: Participant and informant/observer concordance and the relationship of individual items to the complete IS scale were assessed. The short-form (SF) items were selected based on interrater agreement, exploratory factor analysis (EFA), and Item Response Theory (IRT) analysis results. Pair-wise correlation and covariance models were used to examine how SF predicted total IS score in 106 participants from the STAIR (Safety, Tolerability, and Activity of SRX246 in Irritable Subjects with Huntington's Disease) trial. Item Response Theory (IRT) analysis was used to evaluate the range and function of the selected items. RESULTS: IS interrater agreement was statistically significant (r = 0.33, p = .001). In combination with EFA factors and IRT analyses, five items were identified that showed good reliability and performance in differentiating levels of irritability. CONCLUSION: The proposed 5-item SF IS provided a reliable measure of the full scale and may be less burdensome for use in a clinical setting.

The Vasopressin 1a Receptor Antagonist SRX246 Reduces Aggressive Behavior in Huntington's Disease.

SRX246, an orally available CNS penetrant vasopressin (VP) V1a receptor antagonist, was studied in Huntington's disease (HD) patients with irritability and aggressive behavior in the exploratory phase 2 trial, Safety, Tolerability, and Activity of SRX246 in Irritable HD patients (STAIR). This was a dose-escalation study; subjects received final doses of 120 mg BID, 160 mg BID, or placebo. The compound was safe and well tolerated. In this paper, we summarize the results of exploratory analyses of measures of problematic behaviors, including the Cohen-Mansfield Agitation Inventory (CMAI), Aberrant Behavior Checklist (ABC), Problem Behaviors Assessment-short form (PBA-s), Irritability Scale (IS), Clinical Global Impression (CGI), HD Quality of Life (QoL), and Caregiver Burden questionnaires. In addition to these, we asked subjects and caregivers to record answers to short questions about mood, irritability, and aggressive conduct in an eDiary. STAIR was the first rigorously designed study of behavioral endpoints like these in HD. The exploratory analyses showed that SRX246 reduced aggressive acts. Readily observed behaviors should be used as trial endpoints.

Safety and Tolerability of SRX246, a Vasopressin 1a Antagonist, in Irritable Huntington's Disease Patients-A Randomized Phase 2 Clinical Trial.

SRX246 is a vasopressin (AVP) 1a receptor antagonist that crosses the blood-brain barrier. It reduced impulsive aggression, fear, depression and anxiety in animal models, blocked the actions of intranasal AVP on aggression/fear circuits in an experimental medicine fMRI study and demonstrated excellent safety in Phase 1 multiple-ascending dose clinical trials. The present study was a 3-arm, multicenter, randomized, placebo-controlled, double-blind, 12-week, dose escalation study of SRX246 in early symptomatic Huntington's disease (HD) patients with irritability. Our goal was to determine whether SRX246 was safe and well tolerated in these HD patients given its potential use for the treatment of problematic neuropsychiatric symptoms. Participants were randomized to receive placebo or to escalate to 120 mg twice daily or 160 mg twice daily doses of SRX246. Assessments included standard safety tests, the Unified Huntington's Disease Rating Scale (UHDRS), and exploratory measures of problem behaviors. The groups had comparable demographics, features of HD and baseline irritability. Eighty-two out of 106 subjects randomized completed the trial on their assigned dose of drug. One-sided exact-method confidence interval tests were used to reject the null hypothesis of inferior tolerability or safety for each dose group vs. placebo. Apathy and suicidality were not affected by SRX246. Most adverse events in the active arms were considered unlikely to be related to SRX246. The compound was safe and well tolerated in HD patients and can be moved forward as a candidate to treat irritability and aggression.