The combination of the drugs dextromethorphan hydrobromide and quinidine sulfate is approved for the treatment of pseudobulbar affect (a neurologic disorder characterized by episodes of emotional displays such as crying), and there is evidence suggesting a potential benefit of these drugs for agitation. Jeffrey L. Cummings, M.D., Sc.D., of the Cleveland Clinic Lou Ruvo Center for Brain Health, Las Vegas, and colleagues randomly assigned 220 patients to receive dextromethorphan-quinidine (n = 93) or placebo (n = 127) in stage 1. In stage 2, patients receiving dextromethorphan-quinidine continued; those receiving placebo were stratified by response and re-randomized to dextromethorphan-quinidine (n = 59) or placebo (n = 60). The 10 week trial was conducted at 42 study sites.
A total of 194 patients (88 percent) completed the study. Analysis combining stages 1 (all patients) and 2 (re-randomized placebo nonresponders) showed significantly reduced measures of agitation (occurrence and severity of symptoms). Patients treated with only dextromethorphan-quinidine had an average 51 percent reduction in the measure of agitation from baseline to week 10, compared with 26 percent for those treated with only placebo.