VYALEV
Clinical safety rating: caution
Comprehensive clinical and safety monograph for VYALEV (VYALEV).
VYALEV (foslevodopa/foscarbidopa) is a combination of a levodopa prodrug (foslevodopa) and a carbidopa prodrug (foscarbidopa). Foslevodopa is converted to levodopa, which is decarboxylated to dopamine in the brain, restoring dopamine levels in the striatum. Foscarbidopa is converted to carbidopa, which inhibits peripheral decarboxylation of levodopa, increasing levodopa availability to the brain.
| Metabolism | Foslevodopa is converted to levodopa by alkaline phosphatase; levodopa is metabolized by aromatic L-amino acid decarboxylase (AAAD) and catechol-O-methyltransferase (COMT). Foscarbidopa is converted to carbidopa, which is metabolized by unidentified pathways. |
| Excretion | Foslevodopa is primarily eliminated renally as metabolites (levodopa and its metabolites, including 3-O-methyldopa and dopamine metabolites). Approximately 70-80% of the dose is excreted in urine, with <10% as unchanged levodopa. Fecal excretion accounts for <5%. Foscarbidopa is hydrolyzed to carbidopa, which is excreted mainly renally (60-70% as unchanged drug and metabolites). Biliary excretion is minimal. |
| Half-life | The terminal elimination half-life of levodopa from foslevodopa/foscarbidopa is approximately 2.5-3 hours. In the context of continuous subcutaneous infusion, steady-state concentrations are maintained without significant peaks and troughs, allowing for constant dopaminergic stimulation. The half-life of carbidopa is similar (2-3 hours). |
| Protein binding | Levodopa: approximately 10-30% bound to plasma proteins (primarily albumin). Carbidopa: approximately 36% bound to plasma proteins. |
| Volume of Distribution | Levodopa: Vd approximately 0.9-1.3 L/kg, indicating distribution into total body water with some tissue binding. Carbidopa: Vd approximately 1.0 L/kg. These values reflect wide distribution but limited CNS penetration of carbidopa. |
| Bioavailability | Subcutaneous administration: Bioavailability of levodopa from foslevodopa is approximately 80-90% relative to intravenous administration. Foscarbidopa is rapidly converted to carbidopa; bioavailability of carbidopa is similar. Continuous subcutaneous infusion provides predictable absorption without first-pass metabolism. |
| Onset of Action | Subcutaneous infusion: Therapeutic effect (improvement in motor symptoms) is typically observed within 30-60 minutes of initiation. A loading dose may provide faster onset. Oral administration: Not applicable; VYALEV is not available orally. |
| Duration of Action | Continuous subcutaneous infusion provides 24-hour coverage. The duration of action is directly related to infusion duration; motor benefits persist as long as the infusion runs. Upon discontinuation, symptoms return within 1-2 hours as drug levels decline. |
Subcutaneous once daily starting dose: foscarbidopa 240 mg/foslevodopa 24 mg, then titrate by 1 mL (60 mg/6 mg) increments, maximum 5 mL (300 mg/30 mg) per day.
| Dosage form | SOLUTION |
| Renal impairment | eGFR ≥30 mL/min: no adjustment. eGFR 15-29 mL/min: reduce dose by 50% and monitor. eGFR <15 mL/min or dialysis: not recommended. |
| Liver impairment | Mild (Child-Pugh A): no adjustment. Moderate (Child-Pugh B): reduce dose by 50%; use with caution. Severe (Child-Pugh C): contraindicated. |
| Pediatric use | Not approved for pediatric use; safety and efficacy not established in patients <18 years. |
| Geriatric use | No specific dose adjustment; monitor renal function and start at low end of dosing range due to age-related renal decline. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for VYALEV (VYALEV).
| Breastfeeding | Levodopa is excreted into human breast milk. The milk-to-plasma ratio for levodopa is approximately 0.26. Carbidopa is likely also excreted. Potential for adverse effects in the nursing infant includes growth retardation and cardiovascular effects. Breastfeeding is not recommended during VYALEV therapy. |
| Teratogenic Risk | VYALEV (foslevodopa/foscarbidopa) is a prodrug combination of levodopa and carbidopa. No human data are available. In animal studies, levodopa caused visceral and skeletal malformations in rabbits at doses similar to human exposure; carbidopa showed no teratogenicity. First trimester exposure carries risk of congenital anomalies. Second and third trimester exposure may be associated with fetal growth restriction and preterm birth. Use only if benefit outweighs risk; consider alternative therapy. |
■ FDA Black Box Warning
None.
| Serious Effects |
["Concurrent use with non-selective monoamine oxidase inhibitors (MAOIs)","History of hypersensitivity to any component","Narrow-angle glaucoma"]
| Precautions | ["Risk of dopamine dysregulation syndrome","Risk of impulse control disorders","Cardiovascular effects including orthostatic hypotension and arrhythmias","Risk of falls due to dyskinesias","Potential for neuroleptic malignant syndrome-like symptoms with abrupt withdrawal","Ocular effects including blurred vision and diplopia","Risk of melanoma development"] |
Loading safety data…
| Fetal Monitoring | Monitor maternal blood pressure, dyskinesias, and hepatic function. Fetal monitoring includes serial ultrasound for growth and anatomy. Consider non-stress testing and biophysical profile in third trimester. Monitor for preterm labor. Postnatal: observe infant for extrapyramidal effects, withdrawal symptoms, and growth parameters. |
| Fertility Effects | Levodopa may affect reproductive function by altering prolactin secretion. In women, levodopa can suppress prolactin, potentially affecting ovulation. In men, levodopa may increase libido but effects on spermatogenesis are unknown. Carbidopa is not expected to have significant fertility effects. VYALEV may impair female fertility via prolactin modulation. |