Section 03 · Monograph
Carbidopa-levodopa ER
Reviewed Nov 2026FDA label
RytaryDopamine precursor · ER
- Forms
- ER cap: 23.75/95, 36.25/145, 48.75/195, 61.25/245mg
- Dose
- Start 23.75/95mg TID x3 days, then 36.25/145mg TID; titrate to effect
- MOA
- Extended-release levodopa/carbidopa
Indications
- Parkinson's disease, post-encephalitic parkinsonism, and symptomatic parkinsonism following carbon monoxide or manganese intoxication (covers Rytary and Crexont extended-release capsules)FDA-labeled
Mechanism of Action
- Levodopa (dopamine precursor) with carbidopa (peripheral decarboxylase inhibitor); capsules combine immediate-release granules with extended-release pellets for longer-lasting plasma levodopa levels
Full Dosing
Adult / usual
- Not substitutable 1:1 with immediate-release carbidopa-levodopa — use each product's conversion table
- Rytary: levodopa-naive patients start 23.75/95mg TID for 3 days, then 36.25/145mg TID; titrate to response; capsule may be opened and sprinkled on applesauce
- Crexont: up to four times daily; maximum 525mg carbidopa/2100mg levodopa per day; swallow whole (do not chew, divide or crush)
- Rytary to Crexont conversion is about 1:1 on levodopa content
- Do not abruptly discontinue; taper
Contraindications
- Nonselective MAO inhibitors (or within 2 weeks)
- Known hypersensitivity
Drug Interactions
- Nonselective MAOIs contraindicated
- Dopamine antagonists and iron salts reduce effect
- High-protein meals reduce absorption
Adverse Effects
- Nausea, dyskinesia, orthostatic hypotension
- Sudden sleep onset, hallucinations or psychosis, impulse control disorders
- Withdrawal-emergent hyperpyrexia and confusion if stopped abruptly
Monitoring Parameters
- Motor fluctuations (OFF time) and dyskinesia
- Blood pressure
- Mental status and impulse-control behaviors
Pregnancy & Lactation
- Limited human data; use only if benefit justifies risk
- Levodopa can suppress lactation; present in milk