Dextromethorphan/Quinidine: in pseudobulbar affect

Pseudobulbar affect (a very unfriendly medical term) describes the uncontrollable and inappropriate laughing and/or crying that occurs in some people with advanced MS. The laughing and crying is typically unrelated to, or out of proportion to, the emotions felt. PwMS and their families find this problem very embarrassing and it often leads to social withdrawal.

This publication reviews the evidence of Dextromethorphan and quinidine as treatment for this problem. The top line results: there was a significantly greater decrease in the rate of pseudobulbar affect episodes per day with Dextromethorphan/quinidine 20 mg/10 mg twice daily compared to placebo.

Why the quinidine? Quinidine inhibits the breakdown of Dextromethorphan which results in higher levels and a longer period of exposure to the drug. A potential downside is that the combination may be associated with a rare cardiac side effect, called QTc prolongation (another unfriendly medical term) and therefore use of this combination will require mandatory ECG or EKG monitoring.

“Healthcare professionals usually underestimated the social impact of pseudobulbar affect; having another treatment for this problem will help. Spread the hope is my motto.”

Garnock-Jones, CNS Drugs. 2011 May 1;25(5):435-45.

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