co-beneldopa
Dopaminergic antiparkinsonian agent· Brands: MadoparPO
Mechanism of action
Co-beneldopa combines levodopa, a dopamine precursor, with benserazide, a peripheral aromatic L-amino acid decarboxylase inhibitor. Levodopa crosses the blood-brain barrier and is converted to dopamine centrally, compensating for the dopaminergic deficit in the basal ganglia. Benserazide blocks peripheral decarboxylation of levodopa, reducing systemic side effects and increasing the amount of levodopa available to the brain.
Pharmacokinetics
Levodopa is absorbed from the proximal small intestine via active transport, with peak plasma concentrations occurring about 1 hour after an oral dose. It is then converted to dopamine by aromatic L-amino acid decarboxylase, but benserazide inhibits this enzyme peripherally, so the main metabolism occurs in the brain. The elimination half-life of levodopa is about 1 to 2 hours. Benserazide is rapidly metabolized and does not significantly penetrate the brain.
Indications & dosing
Parkinson's disease
Doses quoted as levodopa component. Titrate slowly to response.
- adult · PO: 50–200 mg TID · Doses quoted as levodopa component. Titrate slowly to response.
Restless legs syndromeoff-label
Off-label. Doses quoted as levodopa component. Usually given at bedtime.
- adult · PO: 50–100 mg Nocte · Off-label. Doses quoted as levodopa component. Usually given at bedtime.
Contraindications & precautions
- Hypersensitivity to levodopa, benserazide, or any excipient · Risk of anaphylaxis; do not use.
- Narrow-angle glaucoma · Levodopa can increase intraocular pressure.
- Concurrent use of non-selective MAOIs · Wait at least 2 weeks after stopping MAOI before starting co-beneldopa.
- Pheochromocytoma · Increased risk of hypertensive crisis.
- Severe hepatic impairment · Caution; may need dose adjustment or avoidance.
- Severe renal impairment · Caution; monitor renal function.
- Pregnancy · Only if benefit outweighs risk; use contraception.
- Take with food to reduce gastrointestinal upset; however, high-protein meals may reduce levodopa absorption and affect efficacy.
- Do not stop treatment abruptly; withdrawal can cause neurological malignant syndrome-like symptoms.
- Caution in patients with a history of psychotic disorders or dementia, as psychiatric effects may be exacerbated.
- Caution in patients with cardiovascular disease, as arrhythmias and orthostatic hypotension may occur; monitor blood pressure.
- Caution in patients with a history of peptic ulcer disease or gastrointestinal bleeding.
- Caution in patients with diabetes, as blood glucose control may be affected; monitor glucose levels.
Adverse effects
- Nausea and vomiting
- Dyskinesias (involuntary movements)
- Orthostatic hypotension
- Psychiatric effects (confusion, hallucinations, agitation)serious
- Cardiac arrhythmiasserious
- Blood dyscrasias (e.g., agranulocytosis)serious
Interactions
- metoclopramidecontraindicatedDo not prescribe metoclopramide to patients taking co-beneldopa. If antiemetic treatment is required, consider using an alternative antiemetic such as domperidone, which does not cross the blood-brain barrier and is less likely to worsen Parkinson's disease. Alternatively, other antiemetics such as cyclizine may be considered, but always consult current prescribing guidance and specialist advice. Monitor for any deterioration in motor function if an interaction is suspected.
- prochlorperazinecontraindicatedAvoid co-prescription. If an antiemetic is needed, choose a non-dopamine antagonist such as ondansetron or domperidone. For Parkinson's patients, consider specialist advice. Do not use prochlorperazine in patients receiving levodopa-containing products.
Renal & hepatic adjustment
- eGFR 30+: No dose adjustment required for mild to moderate renal impairment.
- eGFR 0–29: Use with caution; consider reducing the dose, as clearance of levodopa and its metabolites may be reduced in severe renal impairment.
- Hepatic impairment (mild): No specific dose adjustment required.
- Hepatic impairment (moderate): Use with caution; no specific dose adjustment has been established.
- Hepatic impairment (severe): Avoid in severe hepatic impairment due to lack of data and potential altered metabolism. (avoid)
Monitoring, pregnancy & toxicity
- Motor response (including dyskinesias and on-off fluctuations) · Regularly, particularly after dose adjustments
- Blood pressure (supine and standing) · Periodically, especially in the elderly or if hypotensive symptoms
- Psychiatric status (e.g., hallucinations, confusion, depression) · At each review
- Full blood count and liver function tests · Periodically during long-term treatment
- Pregnancy: Use only if the potential benefit justifies the potential risk to the fetus. There are insufficient human data; animal studies with levodopa have shown fetal abnormalities. If treatment is essential, use the lowest effective dose. Stopping levodopa in a mother with Parkinson's disease may cause rebound worsening of symptoms, so decisions should be individualized with specialist advice.
- Toxicity: Nausea, vomiting, and orthostatic hypotension · Supportive care, including IV fluids and monitoring of blood pressure. Consider an antiemetic such as domperidone; avoid phenothiazines which may worsen parkinsonism.
- Toxicity: Dyskinesias, agitation, and hallucinations · Reduce or temporarily stop the co-beneldopa. For severe agitation or hallucinations, a benzodiazepine may be used; avoid dopamine antagonists.
- Toxicity: Cardiac arrhythmias (e.g., tachycardia) · Monitor ECG and treat arrhythmias according to standard protocols; correct any electrolyte disturbances.
- Toxicity: Seizures · Standard anticonvulsant treatment with a benzodiazepine (e.g., diazepam) if seizures are prolonged.
Clinical notes
Co-beneldopa is used in the treatment of Parkinson's disease and parkinsonism. It is titrated slowly to avoid adverse effects, which include anorexia, nausea, orthostatic hypotension, and involuntary movements. Dopaminergic effects may also cause hallucinations and confusion, particularly in elderly patients. It should be given with care in patients with cardiac disease, peptic ulcer, or psychiatric symptoms. Interactions with monoamine oxidase inhibitors, iron supplements, and high-protein foods may affect absorption or efficacy. Abrupt withdrawal may cause neuroleptic malignant syndrome.
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BNF; local formulary