Dextromethorphan-quinidine mainly prescribed for dementia, Parkinson's

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Takeaway

  • 57% of patients prescribed the combination of dextromethorphan hydrobromide and quinidine sulfate (Nuedexta) have dementia and/or Parkinson’s disease.

Why this matters

  • Combination's approval by FDA for treatment of pseudobulbar affect in 2010 was based on studies in patients with amyotrophic lateral sclerosis (ALS) or multiple sclerosis (MS).

 Key results

  • Diagnoses in 12,858 commercially insured patients filling prescription for dextromethorphan-quinidine:
    • MS: 8.4%.
    • ALS: 6.8%.
    • Dementia and/or Parkinson’s disease: 57.0%.
  • Patients with contraindications/contraindication indicators:
    • 13.3% had history of heart failure.
    • 38.3% filled prescription for QT-prolonging medication within 30 days.
  • Prescribing providers:
    • General internists: 25.4%.
    • Neurologists: 22.8%.
    • Family practitioners: 17.5%.
    • Psychiatrists: 9.8%.
    • Geriatricians: 5.1%.
    • Nurse practitioners: 4.8%.
    • Physician assistants: 2.5%.
  • Based on Medicare Part D, Centers for Medicare & Medicaid Services data for 2011-2016:
    • Number of patients prescribed medication increased 15.3-fold (from 3296 to 50,402).
    • Spending on medication increased 51.4-fold (from $3.9 million to $200.4 million).

Study design

  • Population-based cohort study using data from 2 commercial insurance databases, Medicare Part D, Centers for Medicare & Medicaid Services.
  • Main outcomes: diagnoses; heart failure history.
  • Funding: Laura and John Arnold Foundation; others.

Limitations

  • Reasons for prescribing unknown.
  • Possible underestimation of prescribing to patients with dementia/Parkinson’s disease.
  • Rebates, discounts not reflected in costs.