Dextromethorphan/quinidine for pseudobulbar affect

Author(s): Steven L Dubovsky

Dextromethorphan/quinidine (DM/Q; NUEDEXTA) is approved by the US FDA for the treatment of pseudobulbar affect (PBA) associated with chronic neurological disorders such as multiple sclerosis, stroke, traumatic brain injury and amyotrophic lateral sclerosis. Studies of applications in other illnesses and for behavioral disinhibition are currently underway. The primary active agent is dextromethorphan, with quinidine added to inhibit its metabolism by CYP450 2D6 and increase the bioavailability of dextromethorphan. Published studies suggest reduction of episodes of PBA and improved quality of life with reasonable tolerability. However, the combination has the potential to interact with a number of other medications used by older patients. Some antidepressants may also be helpful in low doses for PBA and are easier to use, but more controlled studies with validated outcome measures are available for DM/Q. This article reviews published studies of DM/Q and addresses its use in clinical practice.