A 55-year-old man with Parkinson's disease on levodopa/carbidopa 6 times daily has 3-4 hours of 'off' time per day despite optimized levodopa dosing. He has developed dyskinesias in 'on' state. Which add-on therapy is most appropriate to extend 'on' time without worsening dyskinesia?
- A Rasagiline (MAO-B inhibitor)
- B Amantadine
- C Ropinirole (dopamine agonist)
- D Opicapone (COMT inhibitor) ✓
Explanation
Opicapone, a once-daily peripheral COMT inhibitor, extends the plasma half-life of levodopa by inhibiting catechol-O-methyltransferase, thereby smoothing levodopa plasma levels and reducing 'off' time. It does not itself cause dyskinesia enhancement (unlike increasing levodopa dose). In patients who already have levodopa-induced dyskinesia, amantadine (NMDA antagonist) is specifically indicated to reduce dyskinesias without worsening motor fluctuations. Since the question asks about 'off' time extension WITHOUT worsening dyskinesia, opicapone is optimal. MDS 2020 evidence-based review rates opicapone as efficacious for reducing 'off' time.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.