Dextromethorphan/quinidine (trade name Nuedexta) is a combination drug containing dextromethorphan and the class I antiarrhythmic agent quinidine. It is the first FDA-approved drug for the treatment of pseudobulbar affect (PBA). In a 12-week randomized, double-blind trial, amyotrophic lateral sclerosis and multiple sclerosis patients with significant PBA were given either Nuedexta 20/10 mg or placebo. In 326 randomized patients, the PBA-episode daily rate was 46.9% (p < 0.0001) lower for Nuedexta than for placebo.[1] The three deaths in each of the two drug treatment arms and the single death in the placebo arm of the study were believed to be due to the natural course of the disease.[2] Nuedexta was approved in February 2011 and is marketed in the United States by Avanir Pharmaceuticals. Those seemingly unrelated drugs became associated so that low-dose quinidine inhibits dextromethorphan's breakdown. The latter has shown marginal efficacy in pseudobulbar syndrome due to rapid first-pass metabolism that reduces its bioavailability. Common risks and side effects include:[2][3][4] In June 2012, drug discovery and development magazine reported that Avanir Pharmaceuticals plans to test the drug for the treatment of agitation associated with Alzheimer's disease.[5] The drug is also under investigation for the treatment of major depressive disorder.[3][6]

Source:Wikipedia.org