DUOPA
Clinical safety rating: caution
Comprehensive clinical and safety monograph for DUOPA (DUOPA).
DUOPA is a combination of carbidopa and levodopa. Levodopa is a precursor of dopamine that crosses the blood-brain barrier and is converted to dopamine in the brain, replenishing depleted dopamine stores in the striatum. Carbidopa inhibits peripheral decarboxylation of levodopa, increasing the availability of levodopa for transport to the brain.
| Metabolism | Levodopa is metabolized primarily by aromatic L-amino acid decarboxylase (AADC) and catechol-O-methyltransferase (COMT) in the peripheral tissues. Carbidopa inhibits peripheral AADC. |
| Excretion | Renal: carbidopa ~50% unchanged, levodopa minimal; fecal: ~30% of levodopa metabolites; biliary: minor |
| Half-life | Levodopa 1-2 h; carbidopa 1-2 h; clinical context: short t1/2 requires frequent dosing; extended-release formulation prolongs |
| Protein binding | Levodopa ~10% bound to albumin; carbidopa ~36% bound to albumin |
| Volume of Distribution | Levodopa 1.5-2 L/kg, indicating extensive tissue distribution; carbidopa 0.3-0.4 L/kg |
| Bioavailability | Oral: levodopa 70-80% with carbidopa (reduces peripheral metabolism); enteral suspension: ~99% absorbed |
| Onset of Action | Oral: levodopa 0.5-1 h; clinical effect within 1 h |
| Duration of Action | Oral: 4-6 h for immediate-release; longer with Duopa (carbidopa/levodopa enteral suspension) continuous infusion over 16 h |
| Action Class | Analgesic & Antipyretic-PCM |
| Brand Substitutes | Alice 650mg Tablet, Cofamol 650mg Tablet, Algina 650 Tablet, PUC 650 Tablet, Paracip 650 Tablet, Calpol 500mg Tablet, Dolo 500 Tablet, Pacimol 500 Tablet, T-98 Tablet, Parazex 500mg Tablet, Infemol 250mg/5ml Suspension, Chilmol 250mg/5ml Suspension, Pedmol 250mg/5ml Suspension, Unflem 250mg/5ml Suspension, Nicetamol 250mg/5ml Suspension, Flumol 125mg/5ml Suspension, Arden 125mg/5ml Suspension, Pinkbery 125mg/5ml Suspension, Polymol Suspension, Parpol 125mg/5ml Suspension |
One capsule orally, once daily at bedtime. Dose strengths available: 23.75 mg/9.5 mg (carbidopa/levodopa), 36.25 mg/14.5 mg, 48.75 mg/19.5 mg, 61.25 mg/24.5 mg. Titrate based on efficacy and tolerability; maximum dose 61.25 mg/24.5 mg.
| Dosage form | SUSPENSION |
| Renal impairment | No specific guidelines; use with caution in renal impairment. GFR <30 mL/min: not recommended due to lack of data. For GFR 30-60 mL/min: monitor for orthostatic hypotension and neuropsychiatric effects. |
| Liver impairment | Child-Pugh Class A or B: no adjustment needed. Child-Pugh Class C: not recommended (no data). |
| Pediatric use | Safety and efficacy not established in pediatric patients (<18 years). |
| Geriatric use | Elderly patients may require lower initial doses due to increased sensitivity. Start at lowest available strength (23.75 mg/9.5 mg) and titrate slowly. Monitor for hypotension, hallucinations, and dyskinesias. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for DUOPA (DUOPA).
| Breastfeeding | Excretion into human milk unknown; M/P ratio not determined. Levodopa appears in rat milk. Caution advised; consider alternative therapies or avoid breastfeeding due to potential adverse effects in nursing infants. |
| Teratogenic Risk | DUOPA (carbidopa/levodopa enteral suspension) is Pregnancy Category C. First trimester: Limited human data; animal studies show fetal malformations at high doses. Second and third trimesters: May cause fetal harm; avoid unless benefit outweighs risk. Risk of fetal levodopa exposure unknown. |
■ FDA Black Box Warning
None
| Serious Effects |
["Concomitant use with nonselective monoamine oxidase (MAO) inhibitors","Known hypersensitivity to carbidopa, levodopa, or any component of the formulation","Narrow-angle glaucoma (relative; use only if benefit outweighs risk)","History of melanoma or undiagnosed skin lesions"]
| Precautions | ["May cause or exacerbate dyskinesia","Risk of falling asleep during daily activities","Risk of hypotension, especially orthostatic hypotension","May impair mental and/or physical abilities required for driving","Risk of melanoma; periodic skin examinations recommended","May cause hallucinations, psychosis, or impulse control disorders","May cause or worsen glaucoma; monitor intraocular pressure","Contains sulfites; may cause allergic reactions in susceptible individuals"] |
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| Fetal Monitoring |
| Monitor maternal blood pressure, dyskinesias, and psychiatric symptoms. Fetal monitoring: ultrasound for growth and development; consider non-stress test if maternal complications arise. Monitor for premature labor due to uterine contractions reported with levodopa. |
| Fertility Effects | Reproductive toxicity data limited. In animal studies, high-dose levodopa impaired fertility and caused estrous cycle disruption. Human effects on fertility unknown; may inhibit prolactin secretion, potentially affecting ovulation. |