Antiparkinsonian (dopamine precursor + decarboxylase inhibitor) Pregnancy: There are no or limited data in pregnant women and animal studies have shown reproductive toxicity; co-careldopa is not recommended during pregnancy or in women of childbearing potential not using contraception unless the benefits for the mother outweigh the possible risk to the foetus. Levodopa and possibly its metabolites are excreted in human milk and animal studies show excretion of carbidopa in breast milk — breastfeeding should be discontinued during treatment. There are no data on effects on human fertility.

Co-careldopa (carbidopa + levodopa)

Brand names: Sinemet, Sinemet CR, Sinemet Plus, Caramet CR, Half Sinemet CR

Co-careldopa is a combination of levodopa and carbidopa used to treat the motor symptoms of Parkinson's disease.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: Patients NOT already receiving levodopa: dosage may be best initiated with one tablet of co-careldopa 25 mg/100 mg three times a day (providing 75 mg carbidopa per day); if co-careldopa 10 mg/100 mg or 12.5 mg/50 mg tablets are used, dosage may be initiated with one tablet three or four times a day

Route: Oral

Frequency: Three times a day initially (three or four times a day with the lower-strength tablets); the dose may be increased by one tablet every day or every other day as necessary

Max: Up to a dosage equivalent of eight tablets of co-careldopa 25 mg/100 mg a day (two tablets q.d.s.); if co-careldopa 25 mg/250 mg tablets are substituted, the dosage may be increased by one tablet every day or every other day to a maximum of eight tablets a day. Experience with a total daily dosage greater than 200 mg carbidopa is limited

The optimum daily dosage must be determined by careful titration in each patient; response has been observed in one day and sometimes after one dose, with fully effective doses usually reached within seven days. Peripheral dopa-decarboxylase is fully inhibited (saturated) by carbidopa at doses between 70 and 100 mg a day — patients receiving less than this are more likely to experience nausea and vomiting. Because both therapeutic and adverse effects are seen more rapidly than with levodopa alone, monitor patients carefully during dosage adjustment; involuntary movements, particularly blepharospasm, are a useful early sign of excess dosage. PATIENTS ALREADY RECEIVING LEVODOPA: discontinue levodopa at least 12 hours (24 hours for slow-release preparations) before starting co-careldopa — easiest by giving co-careldopa as the first morning dose after a night without levodopa. The dose of co-careldopa should be approximately 20% of the previous daily dosage of levodopa: patients taking less than 1,500 mg levodopa a day should be started on one tablet of co-careldopa 25 mg/100 mg three or four times a day; the suggested starting dose for most patients taking more than 1,500 mg levodopa a day is one tablet of co-careldopa 25 mg/250 mg three or four times a day. MAINTENANCE: individualise and adjust gradually according to response — when a greater proportion of carbidopa is required each 10 mg/100 mg tablet may be replaced with a 25 mg/100 mg or 12.5 mg/50 mg tablet; when more levodopa is required, substitute 25 mg/250 mg tablets at one tablet three or four times a day. PATIENTS RECEIVING LEVODOPA WITH ANOTHER DECARBOXYLASE INHIBITOR: discontinue at least 12 hours before starting co-careldopa and begin with a dosage providing the same amount of levodopa. Other antiparkinsonian agents (other than levodopa alone) may be continued, although their dosage may have to be adjusted. Abrupt dosage reduction or withdrawal must be carefully observed (neuroleptic malignant-like syndrome reported). If a tablet breaks on removal from the packaging, only consume it if the whole dose can be taken — administration of a partial dose may worsen symptoms. PAEDIATRIC: the safety of co-careldopa in patients under 18 years of age has not been established and its use below the age of 18 is not recommended. HEPATIC IMPAIRMENT: administer cautiously and titrate the dose individually. ELDERLY: the recommendations above reflect wide clinical experience in elderly patients. Source: eMC SPC for Co-Careldopa 12.5 mg/50 mg tablets (§4.2).

Dose adjustments

Renal

The impact of renal function on levodopa/carbidopa clearance is limited; co-careldopa should be administered cautiously to patients with renal impairment and the dose should be titrated individually.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to the active substances or to any of the excipients
Non-selective MAO inhibitors and selective MAO type A inhibitors — contraindicated for concomitant use and must be discontinued at least two weeks before starting co-careldopa (co-careldopa may be given with the recommended dose of a selective MAO type B inhibitor such as selegiline)
Narrow-angle glaucoma
Suspicious undiagnosed skin lesions or a history of melanoma (levodopa may activate a malignant melanoma)
Conditions in which adrenergics are contraindicated, e.g. phaeochromocytoma, hyperthyroidism, Cushing's syndrome, severe cardiovascular disease
Severe psychoses

Side effects

Dyskinesias including choreiform, dystonic and other involuntary movements — the most common reactions, usually diminished by dosage reduction; muscle twitching and blepharospasm may be early signs to consider dosage reduction
Nausea and vomiting; dry mouth, bitter taste; constipation, diarrhoea, sialorrhoea, dysphagia
Hallucinations, confusion, dizziness, nightmares, sleepiness, fatigue, insomnia, depression with very rare suicide attempts; somnolence with very rare excessive daytime somnolence and sudden sleep onset episodes
Bradykinetic 'on-off' episodes appearing months to years after starting levodopa, which may require adaptation of dose schedule and dose intervals
Orthostatic hypotension, inclination to faint, syncope; palpitations and irregular heartbeat
Impulse control disorders — pathological gambling, increased libido, hypersexuality, compulsive spending or buying, binge eating and compulsive eating; dopamine dysregulation syndrome

Interactions

Non-selective MAO inhibitors and selective MAO type A inhibitors — contraindicated; discontinue at least two weeks before starting (SPC §4.3)
MAO type B inhibitors (e.g. selegiline hydrochloride) — may be given concomitantly at the manufacturer's recommended dose (SPC §4.3)
Other medicinal products which may cause orthostatic hypotension — co-careldopa may induce orthostatic hypotension, so give cautiously (SPC §4.4)
Neuroleptics — abrupt dosage reduction or withdrawal of co-careldopa in patients also receiving neuroleptics requires careful observation (neuroleptic malignant-like syndrome) (SPC §4.4)
Standard antiparkinsonian drugs other than levodopa alone may be continued, although their dosage may have to be adjusted (SPC §4.2)
Full eMC §4.5 was not captured in the fetched source — verify the complete interaction section

Clinical monograph

How it works

Levodopa is decarboxylated to dopamine within the central nervous system to replace deficient striatal dopamine, while carbidopa inhibits peripheral dopa-decarboxylase, increasing the proportion of levodopa reaching the brain and reducing peripheral adverse effects.

Prescribing in practice

Do not withdraw abruptly, as this can precipitate a neuroleptic malignant syndrome-like reaction.
Chronic therapy is associated with motor fluctuations and dyskinesias that may necessitate adjustment of dose or timing.
Dopaminergic therapy can cause impulse-control disorders and sudden onset of sleep.

Monitoring

Monitor motor symptom control, development of dyskinesias or end-of-dose deterioration, and behavioural effects including impulse-control disorders and somnolence.

Counselling the patient

Do not stop the medicine suddenly; contact the team before making any changes.
Report compulsive behaviours such as gambling, increased sexual urges or compulsive spending or eating.
Some people experience sudden drowsiness, so take care when driving.

Evidence & guidelines

Levodopa with a dopa-decarboxylase inhibitor is the most effective symptomatic treatment for Parkinson's disease and is recommended by NICE.

Reference: SmPC Sinemet; NICE NG71 (Parkinson's disease 2017); MDS Movement Disorders Guidelines; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways