Dextromethorphan/quinidine

Dextromethorphan/quinidine is a combination drug that contains dextromethorphan and quinidine. It is used primarily for the treatment of Pseudobulbar affect, a condition characterized by uncontrollable episodes of crying and/or laughing, or other emotional displays.

Pharmacology

Dextromethorphan is a noncompetitive NMDA receptor antagonist and also acts as a serotonin-norepinephrine reuptake inhibitor. The primary purpose of quinidine in this combination is to inhibit the metabolism of dextromethorphan, thereby increasing its systemic availability and prolonging its effects.

Clinical Use

Dextromethorphan/quinidine is approved by the FDA for the treatment of pseudobulbar affect (PBA). PBA is a neurological condition characterized by uncontrollable episodes of crying and/or laughing, or other emotional displays. It is often seen in people with certain neurological conditions or injuries, such as amyotrophic lateral sclerosis, multiple sclerosis, or Parkinson's disease.

Side Effects

Common side effects of dextromethorphan/quinidine include dizziness, cough, vomiting, peripheral edema, diarrhea, and urinary tract infection. Serious side effects may include thrombocytopenia, hepatotoxicity, serotonin syndrome, and cardiac arrhythmia.

Contraindications

Dextromethorphan/quinidine is contraindicated in patients with a history of hypersensitivity to dextromethorphan or quinidine, in patients with a history of thrombocytopenia or other hematological disease due to quinidine, and in patients taking other drugs that are potent inhibitors of CYP2D6.

See Also

• Dextromethorphan
• Quinidine
• Pseudobulbar affect
• NMDA receptor antagonist
• Serotonin-norepinephrine reuptake inhibitor