Optimizing extended-release carbidopa/levodopa in Parkinson disease

Purpose of review: To help clinicians optimize the conversion of a patient's Parkinson disease pharmacotherapy from immediate-release carbidopa/levodopa (IR CD/LD) to an extended-release formulation (ER CD/LD). Recent findings: Eleven movement disorders specialists achieved consensus positions on the modification of trial-based conversion guidelines to suit individual patients in clinical practice. Summary: Because the pharmacokinetics of ER CD/LD differ from those of IR CD/LD, modification of dosage and dosing frequency are to be expected. Initial regimens may be based on doubling the patient's preconversion levodopa daily dosage and choosing a division of doses to address the patient's motor complications, e.g., wearing-off (warranting a relatively high ER CD/LD dose, possibly at a lower frequency than for IR CD/LD) or dyskinesia (warranting a relatively low dose, perhaps at an unchanged frequency). Patients should know that the main goal of conversion is a steadier levodopa clinical response, even if dosing frequency is unchanged.