This article is more than 5 years old. Information may no longer be current.
Dextromethorphan-quinidine: What PCPs need to know
Click Here to Manage Email Alerts
The FDA approved combined dextromethorphan hydrobromide and quinidine sulfate for the treatment of pseudobulbar affect, a condition characterized by inappropriate and involuntary laughing or crying, in 2010.
The approval was based on studies that evaluated the drug combination in patients with amyotrophic lateral sclerosis or multiple sclerosis.
Since the approval of dextromethorphan-quinidine, however, there has been limited uptake in prescribing the combination agent, and a significant amount of inappropriate prescribing. Healio Internal Medicine spoke with a researcher who has studied the use of dextromethorphan-quinidine about his research and how primary care physicians can best implement the medication.
The combination of dextromethorphan hydrobromide and quinidine sulfate may often be prescribed in patients with dementia and/or Parkinson’s disease despite no known benefits, according to a group of researchers led by Michael Fralick, MD, SM, research fellow in the division of pharmacoepidemiology and pharmacoeconomics and the Program On Regulation, Therapeutics And Law (PORTAL) at Brigham and Women’s Hospital in Boston.
Fralick and colleagues conducted a population-based cohort study, which was published in JAMA Internal Medicine, to examine the prescribing patterns of dextromethorphan-quinidine among patients with amyotrophic lateral sclerosis, MS, dementia, Parkinson’s disease or a history of heart failure — a known contraindication for the medication. The researchers analyzed data from two commercial insurance databases and the Medicare Part D Prescription Drug Program.
A total of 12,858 patients (mean age, 66 years; 66.7% women) in the commercial health care databases filled a prescription for combined dextromethorphan hydrobromide and quinidine sulfate between Oct. 29, 2010, and Mar. 1, 2017. Of these patients, few had a diagnosis of MS (8.4%) or amyotrophic lateral sclerosis (6.8%), but many had a diagnosis of dementia and/or Parkinson’s disease (57%). Additionally, 13.3% of patients who filled a prescription of the drug had a history of heart failure.
Among patients in the Medicare Part D database, there was a 15-times increase in the number of prescriptions of dextromethorphan-quinidine from 2011 (n = 3,296) to 2016 (n = 50,402).
Healio Internal Medicine spoke with Fralick to discuss how physicians can prescribe dextromethorphan-quinidine more appropriately. – by Alaina Tedesco
Question: What do PCPs need to know to use dextromethorphan-quinidine more appropriately?
Answer: It is important that physicians realize this medication was primarily studied in patients with amyotrophic lateral sclerosis and MS. There are very little data to support its use in patients who do not have either condition. The medication is associated with significant side effects including falls, UTIs and confusion.
Most patients with amyotrophic lateral sclerosis or MS do not need, or will not benefit from, this medication. It should only be considered in a small subset of patients who also have significant pseudobulbar affect.
Q: What is the PCP’s role in administering dextromethorphan-quinidine?
A: The medication is a pill that combines two ingredients: dextromethorphan (the active ingredient in cough syrup) and quinidine (used to increase the concentration of dextromethorphan). I would recommend extreme caution in prescribing this medication because of the adverse events associated with it.
Q: What do physicians need to consider when prescribing dextromethorphan-quinidine?
A: This medication should not be used in patients with a history of heart failure or patients on certain medications that may interact with it. Since the medication can be quite sedating, it is important to warn patients about this and avoid using it in patients who already have an altered level of consciousness.
Q: Why is there a lack of uptake of the medication in patients with pseudobulbar affect? What can be done about it?
A: The exact uptake in patients with pseudobulbar affect is hard to quantify using insurance claims database as we have done, since some physicians might not have specifically noted the patient has pseudobulbar affect.
Q: Since dextromethorphan-quinidine is not necessary in patients with amyotrophic lateral sclerosis, MS, dementia or Parkinson’s disease, what can be done to reduce prescriptions of the medication in these patients?
A: To clarify, this medication is approved for patients who have pseudobulbar affect. If this is related to a diagnosis of amyotrophic lateral sclerosis or MS then some patients may benefit from this medication. As a physician, I would not recommend this medication be used in patients with dementia or Parkinson’s disease because the risks outweigh the benefits.
Reference:
Fralick M, et al. JAMA Intern Med. 2019;doi:10.1001/jamainternmed.2018.6112.
Disclosure: Fralick reports no relevant financial disclosures. Please see study for all other authors’ relevant financial disclosures.