Co-careldopa (carbidopa + levodopa)

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.