Dextromethorphan-quinidine should be used with caution for older adults because:

• A. It has limited efficacy for dementia behavioral symptoms and may increase falls and drug interactions, especially in those with heart failure.
• B. It is highly effective for dementia behavioral symptoms and has no cardiac risks.
• C. It is contraindicated in all older adults.
• D. It improves heart function in most patients.

Answer: (C)

Dextromethorphan-quinidine is flagged for older adults because safety concerns greatly outweigh any potential benefit in this population. The quinidine component can cause QT interval prolongation, which can lead to serious, potentially life-threatening heart rhythms, especially in older adults who may have underlying heart disease or who are taking other medications that affect the heart’s rhythm. In addition, older adults are more prone to drug–drug interactions with this combination, along with central nervous system effects such as dizziness, confusion, and delirium, all of which raise the risk of falls and other adverse events. Because these risks are substantial and the benefit for dementia-related behavioral symptoms is limited, many guidelines categorize this therapy as contraindicated in older adults. The other options imply strong efficacy or cardiac benefit, which contradicts the safety profile and is not consistent with how this drug is viewed in Beers Criteria contexts.