Section 03 · Monograph

Foslevodopa-foscarbidopa

Reviewed Nov 2026FDA label

VyalevDopamine precursor · SC infusion

Indications

Treatment of motor fluctuations in adults with advanced Parkinson's diseaseFDA-labeled

Foscarbidopa and foslevodopa are water-soluble prodrugs of carbidopa and levodopa, enzymatically converted in vivo (via alkaline phosphatase) to carbidopa and levodopa, enabling continuous subcutaneous delivery
Levodopa crosses the blood-brain barrier and is decarboxylated to dopamine, replenishing striatal dopamine deficient in Parkinson's disease
Carbidopa inhibits peripheral aromatic-L-amino-acid decarboxylase, reducing peripheral levodopa metabolism and increasing CNS levodopa availability while limiting peripheral adverse effects (e.g., nausea)
Continuous subcutaneous infusion provides steady-state plasma levodopa/carbidopa concentrations (achieved within ~2 hours with a loading dose), reducing pulsatile dopaminergic stimulation compared with oral dosing
Levodopa elimination half-life ~1.5 hours; carbidopa elimination half-life ~2 hours with this formulation

Continuous subcutaneous infusion via the VYAFUSER pump, administered to the abdomen (avoiding a 2-inch radius around the navel); thigh and upper arm are alternative sites
Dose is individualized: convert the patient's current Total Levodopa Dosage (TLD, immediate-release equivalents, excluding nighttime and rescue doses)
VYALEV daily dose (mg foslevodopa) = TLD x 1.3; daily volume = daily dose ÷ 240 mg/mL concentration; hourly infusion rate = daily volume ÷ number of waking hours (typically ~16 hours)
Optional loading dose at infusion start, calculated from the patient's usual first morning oral dose x 1.3 ÷ 240 (typical range 0.1–3 mL)
Up to five programmable extra (bolus) doses are available (0.1–0.3 mL, ~17–51 mg levodopa equivalent) for breakthrough OFF symptoms; no more than one extra dose per hour
Maximum total daily dose: 3,525 mg foslevodopa (approximately 2,500 mg levodopa equivalent)
Change infusion set/site at least every 3 days; rotate to a new site at least 1 inch from any site used in the prior 12 days
Evaluate and correct vitamin B6 deficiency before initiation
Keep an oral carbidopa-levodopa supply available for infusion interruptions
Do not stop abruptly; taper to avoid withdrawal-emergent hyperpyrexia and confusion

Concurrent use of a nonselective monoamine oxidase (MAO) inhibitor, or use within the preceding 2 weeks, due to risk of hypertensive crisis

Nonselective MAO inhibitors: contraindicated — risk of hypertensive crisis; discontinue ≥2 weeks before starting VYALEV
Selective MAO-B inhibitors (selegiline, rasagiline): increased risk of orthostatic hypotension; monitor blood pressure
Antihypertensive agents: increased risk of symptomatic postural hypotension; antihypertensive dose adjustment may be needed
Dopamine D2-receptor antagonists (e.g., antipsychotics, metoclopramide): may reduce foslevodopa-foscarbidopa efficacy and worsen parkinsonian symptoms
Isoniazid: may reduce therapeutic effect of levodopa
Iron salts/multivitamins containing iron: may reduce levodopa bioavailability via chelation

Infusion site reactions (erythema, pain, edema, nodule, bruising, induration, pruritus, hematoma) — occurred in 62% of patients in clinical trial vs 8% on oral therapy
Infusion site infections, including cellulitis — occurred in 28% vs 3% on oral therapy
Hallucinations (12.2% vs 1.5%) and psychosis (4.1% vs 1.5%)
Dyskinesia (11% vs 6%)
About 22% of patients discontinued therapy due to adverse events, most commonly hallucinations and infusion site reactions/infections

Daily inspection of infusion sites for infection, inflammation, or reaction; rotate sites per schedule
Vitamin B6 levels before initiation and periodically thereafter; supplement if deficient
Blood pressure, particularly during dose escalation or when combined with MAO-B inhibitors/antihypertensives
Screen for daytime somnolence/sudden sleep episodes and counsel on driving/operating machinery
Assess for hallucinations, psychosis, and new or increased impulse control behaviors (gambling, hypersexuality, compulsive eating/shopping) via direct questioning of patient and caregiver
Intraocular pressure in patients with glaucoma
Cardiac status in patients with history of ischemic heart disease

No adequate human pregnancy data; based on animal data (carbidopa-levodopa related visceral/skeletal malformations in rabbits), may pose fetal risk
Levodopa is present in human milk and may decrease prolactin secretion, potentially inhibiting lactation; no data on foscarbidopa/foslevodopa specifically in human milk
Discuss individual risks/benefits of breastfeeding with the patient