Nuedexta, developed and commercialized by Avanir Pharmaceuticals, is a treatment approved by the U.S. Food and Drug Administration (FDA) to treat involuntary episodes of crying or laughing, known as the pseudobulbar affect (PBA). People with multiple sclerosis (MS), as well as those with other neurological disorders, can experience PBA.

How Nuedexta works

Nuedexta is composed of dextromethorphan and quinidineAlthough the mechanism of action of Nuedexta is not fully understood, researchers think dextromethorphan affects the way signals are transmitted between brain cells via chemicals called neurotransmitters, which control emotions. By normalizing the activity of these neurotransmitters, Nuedexta helps regulate the uncontrollable emotional outbursts seen in MS patients with PBA.

Quinidine helps increase the amount of dextromethorphan available in the blood, enhancing its therapeutic effect.

Nuedexta in clinical trials

The safety and effectiveness of Nuedexta were assessed in a Phase 3 trial (NCT00050232) in 150 MS patients with PBA. The results of the trial, published in the journal Annals of Neurology, showed that patients receiving Nuedexta had greater reductions in Center for Neurologic Study-Lability Scale (CNS-LS) scores compared to those receiving placebo. The CNS-LS is a self-administered questionnaire used by professionals to identify and measure symptoms suggestive of PBA.

Moreover, the number of crying or laughing episodes, quality of life, quality of relationships, and pain intensity scores were all better in patients who received Nuedexta compared to those who received placebo. Overall, Nuedexta was well-tolerated among all patients with only dizziness occurring with greater frequency in the Nuedexta-treated group than the placebo-treated group.

Another Phase 3 study (NCT00573443) evaluated the safety, effectiveness, and pharmacokinetics (movement in the body) of two doses of Nuedexta in the treatment of PBA patients with MS and ALS (amyotrophic lateral sclerosis). The results were published in the journal Annals of Neurology and showed that the number of PBA episodes in people receiving Nuedexta was nearly half that of people receiving placebo across the 12 weeks of the study. Additionally, patients treated with Nuedexta presented better secondary outcomes like CNS-LS, the likelihood of PBA remission and, measures of social functioning and mental health compared to those given placebo.

Avanir also evaluated the safety, tolerability, and effectiveness of three doses of Nuedexta for the treatment of central neuropathic pain in MS patients in a Phase 2 trial called PRIME (NCT01324232). The primary effectiveness goal of this trial was the numeric pain rating scale (NPRS) as recorded in patient diaries. Secondary assessments included measures of fatigue, the impact of MS on daily life, sleep quality, and cognition (thinking ability), and depression.

The results of the trial showed that patients experienced a reduction in the levels of pain, but without differences between the treatment and placebo arms of the study. Avanir stated that a higher-than-expected placebo response negatively impacted the results of the study. 

Other details

Some side effects of Nuedexta are diarrhea, dizziness, cough, vomiting, weakness, and swelling of the feet and ankles.

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