Effect of Dextromethorphan-Quinidine on Agitation in Patients With Alzheimer Disease Dementia A Randomized Clinical Trial

IMPORTANCE Agitation is common among patients with Alzheimer disease; safe, effective treatments are lacking. OBJECTIVE To assess the efficacy, safety, and tolerability of dextromethorphan hydrobromide-quinidine sulfate for Alzheimer disease-related agitation. DESIGN, SETTING, AND PARTICIPANTS Phase 2 randomized, multicenter, double-blind, placebo-controlled trial using a sequential parallel comparison design with 2 consecutive 5-week treatment stages conducted August 2012-August 2014. Patients with probable Alzheimer disease, clinically significant agitation (Clinical Global Impressions-Severity agitation score >= 4), and a Mini-Mental State Examination score of 8 to 28 participated at 42 US study sites. Stable dosages of antidepressants, antipsychotics, hypnotics, and antidementia medications were allowed. INTERVENTIONS In stage 1, 220 patients were randomized in a 3: 4 ratio to receive dextromethorphan-quinidine (n = 93) or placebo (n = 127). In stage 2, patients receiving dextromethorphan-quinidine continued; those receiving placebo were stratified by response and rerandomized in a 1: 1 ratio to dextromethorphan-quinidine (n = 59) or placebo (n = 60). MAIN OUTCOMES AND MEASURES The primary end point was change from baseline on the Neuropsychiatric Inventory (NPI) Agitation/Aggression domain (scale range, 0 [absence of symptoms] to 12 [symptoms occur daily and with marked severity]). RESULTS A total of 194 patients (88.2%) completed the study. With the sequential parallel comparison design, 152 patients received dextromethorphan-quinidine and 127 received placebo during the study. Analysis combining stages 1 (all patients) and 2 (rerandomized placebo nonresponders) showed significantly reduced NPI Agitation/Aggression scores for dextromethorphan-quinidine vs placebo( ordinaryleastsquareszstatistic,-3.95; P < .001). In stage 1, mean NPI Agitation/Aggression scores were reduced from 7.1 to 3.8 with dextromethorphan-quinidine and from 7.0 to 5.3 with placebo. Between-groupt reatment differences were significantin stage 1(leasts quaresmean, -1.5; 95% CI, -2.3 to -0.7; P <. 001). In stage 2, NPI Agitation/Aggression scores were reduced from 5.8 to 3.8 with dextromethorphan-quinidine and from 6.7 to 5.8 with placebo. Between-group treatment differences were also significant in stage 2(least squares mean,-1.6; 95% CI,-2.9 to -0.3; P=.02). Adverseevents included falls (8.6% for dextromethorphan-quinidine vs3.9% for placebo), diarrhea (5.9% vs 3.1% respectively), and urinary tract infection (5.3% vs 3.9% respectively). Serious adverse events occurred in 7.9% with dextromethorphan-quinidine vs 4.7% with placebo. Dextromethorphan-quinidinewas not associated with cognitive impairment, sedation, or clinically significant QTc prolongation. CONCLUSIONS AND RELEVANCE In this preliminary 10-week phase 2 randomized clinical trial of patients with probable Alzheimer disease, combination dextromethorphan-quinidine demonstrated clinically relevant efficacy for agitation and was generally well tolerated.