Pharmacology · Dopaminergic antiparkinson agents (levodopa and amantadine)
Levodopa + benserazide !
The other levodopa combination, common outside the US. Benserazide plays the same role as carbidopa: it stops levodopa being wasted outside the brain.
Updated 2026-11-01
Also called: Co-beneldopa
The figure shows carbidopa, which acts like benserazide, bound to pig DOPA decarboxylase; both inhibitors block this enzyme outside the brain.
Mechanism of action
As with carbidopa, benserazide inhibits aromatic L-amino acid decarboxylase in the periphery without entering the brain. More levodopa crosses into the brain and is converted to dopamine in the striatum, with less nausea and hypotension from dopamine made in the blood.
- Benserazide blocks DOPA decarboxylase outside the brain
- More levodopa crosses the blood-brain barrier
- Striatal dopamine is restored; movement improves
Pharmacokinetics
- Absorption
- Capsules, slow-release capsules and dispersible tablets; protein, iron and antacids can reduce absorption
- Onset and duration
- Effect begins after the first dose; full effect can take a few weeks
Indications
- Motor symptoms of Parkinson disease (tremor, slowness, stiffness) Parkinson disease →
Adverse effects
Common
- Nausea, vomiting and loss of appetite
- Dizziness on standing
- Insomnia and taste change
- Dyskinesias, more with long use or high doses
- Discoloured urine, saliva or teeth (harmless)
Contraindications
- Hypersensitivity to levodopa or benserazide
- Not usually given to people under 25
- Caution: glaucoma, melanoma, psychosis, heart disease, peptic ulcer, liver or kidney disease
Key interactions
- Nonselective MAO inhibitors (tranylcypromine, phenelzine, isocarboxazid)
- Dangerous rise in blood pressure; avoided, including within two weeks
- Antipsychotics (haloperidol, risperidone) and antiemetics (metoclopramide, prochlorperazine)
- Block dopamine and reduce the effect
- Iron supplements and antacids
- Change absorption
- Antihypertensives
- More dizziness on standing
What is monitored
- Motor response, dyskinesias and off periods
- Mood, hallucinations, impulse control and daytime sleep
- Blood pressure lying and standing
- Skin checks for melanoma
Administration and safety
- Given at the same times each day
- Never stopped suddenly; the team plans how to continue it around surgery
- Standard, slow-release and dispersible forms are not interchangeable
Nursing care
- Give doses on time in hospital: missed doses cause off periods
- Check orthostatic blood pressure and falls
- Ask about gambling, shopping, eating or sexual changes and craving for extra doses
- Explain that coloured urine or saliva is harmless
Pregnancy and breastfeeding
Rarely used in pregnancy because information is limited; it may be used when benefits outweigh risks.
Test yourself
Think of the answer, then tap the question to see it.
What is the role of benserazide in levodopa + benserazide?
It inhibits peripheral DOPA decarboxylase, like carbidopa, so more levodopa reaches the brain.
Which antiemetics should be avoided with levodopa + benserazide?
Dopamine blockers such as metoclopramide and prochlorperazine.
What is dopamine dysregulation syndrome?
Compulsive craving for more levodopa than is needed to control symptoms.
Related drugs
Related conditions
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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: About co-beneldopa (NHS, 2025); Side effects of co-beneldopa (NHS, 2025); Who can and cannot take co-beneldopa (NHS, 2025); Taking co-beneldopa with other medicines and herbal supplements (NHS, 2025).
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Representative model, for educational purposes only.