Key takeaways
Selegiline (Zelapar) and carbidopa/levodopa (Duopa) are both prescription medications used to treat movement problems associted with Parkinson's disease (PD). However, they belong to different medication classes and have some important differences. Selegiline is a monoamine oxidase type B (MAO-B) inhibitor that helps keep dopamine in the brain longer, while carbidopa/levodopa is a combination of a dopa decarboxylase inhibitor and a dopamine replacement that directly increases dopamine levels. Selegiline is available in oral tablets, capsules, and orally disintegrating tablets (ODT), whereas Duopa is administered through a PEG-J tube using an infusion pump. Selegiline is typically taken once or twice a day, while Duopa is given over 16 hours, beginning in the morning. Common side effects of selegiline include nausea and dizziness, while Duopa can cause nausea, constipation, and issues related to tube placement. Selegiline has many drug interactions, including with other medications that affect serotonin, while Duopa shoud be taken at a different time than any iron-containing products to ensure proper absorption.
