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Original Investigation
January 7, 2019

Assessment of Use of Combined Dextromethorphan and Quinidine in Patients With Dementia or Parkinson Disease After US Food and Drug Administration Approval for Pseudobulbar Affect

Author Affiliations
  • 1Program On Regulation, Therapeutics, And Law (PORTAL), Division of Pharmacoepidemiology and Pharmacoeconomics, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
  • 2Eliot Phillipson Clinician Scientist Training Program, Department of Medicine, University of Toronto, Toronto, Ontario, Canada
JAMA Intern Med. Published online January 7, 2019. doi:10.1001/jamainternmed.2018.6112
Key Points

Question  After US Food and Drug Administration approval for treatment of pseudobulbar affect based on clinical trials conducted in patients with multiple sclerosis and amyotrophic lateral sclerosis, what patients received combined dextromethorphan hydrobromide and quinidine sulfate?

Findings  In this population-based cohort study of 12 858 patients in 2 commercial insurance databases who filled a prescription for the medication, most had a diagnosis of dementia and/or Parkinson disease. Reported Medicare spending on dextromethorphan-quinidine increased from $3.9 million in 2011 to $200.4 million in 2016; the number of patients receiving the medication increased from 3296 to 50 402 in the same period.

Meaning  Dextromethorphan-quinidine appears to be primarily prescribed for patients with dementia and/or Parkinson disease, although its preapproval studies of efficacy were performed in patients with other diagnoses.

Abstract

Importance  In 2010, the US Food and Drug Administration (FDA) approved a combination of dextromethorphan hydrobromide and quinidine sulfate for the treatment of pseudobulbar affect after studies in patients with amyotrophic lateral sclerosis (ALS) or multiple sclerosis (MS). This medication, however, may be commonly prescribed in patients with dementia and/or Parkinson disease (PD).

Objective  To investigate the prescribing patterns of dextromethorphan-quinidine, including trends in associated costs.

Design, Setting, and Participants  This population-based cohort study of patients prescribed dextromethorphan-quinidine used data from 2 commercial insurance databases, Optum Clinformatics Data Mart and Truven Health MarketScan. The Medicare Part D Prescription Drug Program data set was used to evaluate numbers of prescriptions and total reported spending by the Centers for Medicare & Medicaid Services. Patients were included if they were prescribed dextromethorphan-quinidine from October 29, 2010, when the drug was approved, through March 1, 2017, for Optum and December 31, 2015, for Truven. Data were analyzed from December 1, 2017, through August 1, 2018.

Main Outcomes and Measures  The proportion of patients prescribed dextromethorphan-quinidine with a diagnosis of MS, ALS, or dementia and/or PD, as well as the number of patients with a history of heart failure (a contraindication for the drug).

Results  In the commercial health care databases, 12 858 patients filled a prescription for dextromethorphan-quinidine during the study period. Mean (SD) age was 66.0 (18.5) years, 66.7% were women, and 13.3% had a history of heart failure. Combining results from both databases, few patients had a diagnosis of MS (8.4%) or ALS (6.8%); most (57.0%) had a diagnosis of dementia and/or PD. In the Medicare Part D database, the number of patients prescribed dextromethorphan-quinidine increased 15.3-fold, from 3296 in 2011 to 50 402 in 2016. Reported spending by Centers for Medicare & Medicaid Services on this medication increased from $3.9 million in 2011 to $200.4 million in 2016.

Conclusions and Relevance  Despite approval by the FDA for pseudobulbar affect based on studies of patients with ALS or MS, dextromethorphan-quinidine appears to be primarily prescribed for patients with dementia and/or PD.

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    1 Comment for this article
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    What is the thrust of this article?
    Robert Wang, Ph.D., M.D. | Primary practice
    The facts reviewed in this article appear accurate within the limitations of the available data. The trends described, the financial considerations, and the potential risks are consistent with the experience of clinicians who practice in this field.

    However, the thrust of the article appears to be more concerned about the health of our regulatory process, rather than the care of the patients in this functionally debilitated class.

    Yes, this medication is being prescribed to those with labile behavior associated with brain disease of many kinds. It is being used because it is somewhat clinically effective in
    the experience of clinicians in the field. Yes, it has adverse drug risks, but those risks appear much less severe than behavioral interventions such as neuroleptics, benzodiazepines, and probably anti-epileptics, certainly than most antihistamines. So rather than concentrate on the regulation of prescribing this medication because it is newer, and data bases allow easy data collection, why not insist that efficacy studies be pursued immediately, especially since you quote a price of 69 cents for the generic medication dosing.

    Article such as this should not be directed to suppressing clinical benefit, but to improving the regulatory process and access to low cost generics which add to public health, not subtract from it.
    CONFLICT OF INTEREST: None Reported
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