Drugs Home > Dextromethorphan and Quinidine

Drug Interactions

Dextromethorphan and quinidine may react with a number of other medications (see Drug Interactions With Dextromethorphan and Quinidine).

What If I Overdose on This Medication?

An overdose with dextromethorphan and quinidine can be dangerous, as it may cause potentially serious heart rhythm problems. If you happen to overdose on this medication, seek immediate medical attention.
(Click Nuedexta Overdose for more information.)

What Should I Do If I Forget a Dose?

If you forget to take your dose of dextromethorphan and quinidine, simply skip your missed dose and continue with your regular schedule. Do not take a double dose of this medicine or take more than two capsules in a day.

How Does It Work?

The exact way dextromethorphan and quinidine works to treat pseudobulbar affect is unknown. Dextromethorphan, one of the active ingredients in the medicine, is known to work in the brain. It is commonly found in cough and cold products, because it has actions in the "cough center" of the brain, where it suppresses coughing.
Dextromethorphan blocks N-methyl-D-aspartate receptors (more commonly called NMDA receptors), preventing the action of glutamate, an excitatory brain chemical. It also binds to sigma receptors. The role of sigma receptors in the brain is not clearly established, but researchers believe they may play a role in certain neurological conditions.
Quinidine, the other active ingredient in the drug, slows down the rate at which the body breaks down dextromethorphan. This increases dextromethorphan blood levels, increasing dextromethorphan's effect in the body.
Written by/reviewed by:
Last reviewed by: Kristi Monson, PharmD;
Last updated/reviewed:
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