Pseudobulbar affect (PBA) occurs in people with brain injury or underlying neurological conditions such as multiple sclerosis, amyotrophic lateral sclerosis and Parkinson’s disease and is characterised by unpredictable and uncontrollable fits of laughing or crying that may not reflect the individual’s underlying mood or may be inappropriate to the situation. Because many people feel embarrassed by their symptoms, PBA can have a significant effect on quality of life since sufferers tend to withdraw from social and professional activities. So far, there has been no specific treatment but, last week, the FDA approved Nuedexta™ as the first treatment of PBA.
Nuedexta™ is a combination of dextromethorphan, a component of some over-the-counter cough mixtures and the antiarrhythmic agent, quinidine, which acts as a metabolic inhibitor, allowing effective concentrations of dextromethorphan to be achieved.
Dextromethorphan acts on sigma-1 and NMDA receptors in the brain, although exactly how it exerts its therapeutic effects in patients with PBA is not known. Nuedexta™ has been shown to be safe and effective in patients with multiple sclerosis and amyotrophic lateral sclerosis but not in other groups of patients who may experience PBA, such as those with Alzheimer’s disease.
Nuedexta™ was developed by Avanir Pharmaceuticals, Inc. and is expected to be available by prescription in the US during the first quarter of 2011.