LARODOPA
Clinical safety rating: caution
Comprehensive clinical and safety monograph for LARODOPA (LARODOPA).
Larodopa is a prodrug of dopamine that crosses the blood-brain barrier and is decarboxylated to dopamine in the brain, thereby restoring dopaminergic neurotransmission in the striatum, compensating for the loss of nigrostriatal dopaminergic neurons in Parkinson's disease.
| Metabolism | Larodopa is extensively metabolized primarily by decarboxylation via aromatic L-amino acid decarboxylase (AADC) and O-methylation via catechol-O-methyltransferase (COMT). Peripheral metabolism is significant, and concomitant administration of a peripheral decarboxylase inhibitor (e.g., carbidopa) is used to increase central availability. |
| Excretion | Renal excretion of metabolites (mainly 3-O-methyldopa, homovanillic acid, dihydroxyphenylacetic acid); <1% unchanged; ~70-80% total eliminated in urine, ~5-10% in feces via bile. |
| Half-life | 1-3 hours (levodopa alone); 1.5-2 hours (with carbidopa); clinical context: short half-life necessitates frequent dosing and contributes to motor fluctuations. |
| Protein binding | ~10-30% (mainly bound to albumin, minimal binding to alpha-1-acid glycoprotein). |
| Volume of Distribution | 0.9-1.6 L/kg; indicates extensive distribution into tissues, including brain (penetrates via L-type amino acid transporter). |
| Bioavailability | Oral (immediate-release with carbidopa): 70-80%; oral (immediate-release alone): 10-30% (due to extensive decarboxylation); oral (extended-release with carbidopa): 50-70%. |
| Onset of Action | Oral (immediate-release): 0.5-2 hours; oral (extended-release): 1-3 hours; IV: 5-15 minutes. |
| Duration of Action | Oral (immediate-release): 4-6 hours; oral (extended-release): 6-8 hours; clinical context: duration shortens with disease progression, leading to wearing-off effects. |
300 mg orally once daily, taken with a low-fat meal in the morning.
| Dosage form | TABLET |
| Renal impairment | No adjustment needed for GFR ≥30 mL/min; not recommended for GFR <30 mL/min. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: 200 mg once daily; Child-Pugh C: not recommended. |
| Pediatric use | Weight-based: 10 mg/kg orally once daily, max 300 mg/day. |
| Geriatric use | Start at 200 mg once daily; increase to 300 mg if tolerated and needed. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for LARODOPA (LARODOPA).
| Breastfeeding | Levodopa is excreted into human breast milk. The milk-to-plasma (M/P) ratio is approximately 0.35. Limited data suggest low concentrations relative to maternal dose. However, potential adverse effects on the nursing infant include changes in dopamine receptor sensitivity. Caution is advised; decision to breastfeed should consider maternal need for therapy and infant monitoring. |
| Teratogenic Risk | Larodopa (levodopa) is classified as FDA Pregnancy Category C. In animal studies, it has been shown to cause visceral and skeletal malformations at doses similar to human therapeutic levels. There are no adequate and well-controlled studies in pregnant women. Potential risks include fetal developmental abnormalities, particularly during the first trimester. Use only if potential benefit justifies potential risk to the fetus. |
■ FDA Black Box Warning
Larodopa may cause severe psychiatric disturbances, including suicidal ideation, psychosis, and severe depression. Patients should be monitored closely for changes in mood, behavior, and suicidal thoughts. Larodopa should be avoided in patients with a history of psychotic disorders or suicide attempts.
| Serious Effects |
Hypersensitivity to larodopa or any component of the formulation. Concurrent use with nonselective monoamine oxidase inhibitors (MAOIs) such as phenelzine or tranylcypromine (risk of hypertensive crisis). Narrow-angle glaucoma. Melanoma (suspected or diagnosed). History of malignant melanoma. Lactation.
| Precautions | May cause dyskinesias, orthostatic hypotension, and gastrointestinal bleeding. Neuroleptic malignant syndrome-like symptoms may occur with rapid dose reduction or withdrawal. Caution in patients with history of myocardial infarction, arrhythmias, or peptic ulcer disease. May cause somnolence and sudden sleep onset. Must not be abruptly discontinued; taper slowly. |
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| Fetal Monitoring | Monitor maternal blood pressure, heart rate, and parkinsonian symptoms. Consider fetal ultrasound for growth and development if used during pregnancy. In newborns, observe for extrapyramidal symptoms or withdrawal effects due to dopamine depletion. |
| Fertility Effects | Animal studies suggest that levodopa may interfere with reproductive function, including decreased fertility and implantation rates. In humans, limited data indicate possible menstrual irregularities and reduced libido. Effects on male fertility are unknown. |