BMA Concise Guide to Medicine & Drugs

Levodopa/Co-Beneldopa/Co-Careldopa

Brand names None

Used in the following combined preparations Duodopa, Madopar, Madopar CR, Sinemet, Sinemet CR, Stalevo

QUICK REFERENCE

Drug group Drug for parkinsonism

Overdose danger rating Medium

Dependence rating Low

Prescription needed Yes

Available as generic Yes

GENERAL INFORMATION

The treatment of Parkinson’s disease underwent dramatic change in the 1960s with the introduction of levodopa. Since the body can transform levodopa into dopamine, a chemical messenger in the brain the absence or shortage of which causes Parkinson’s disease, rapid improvements in control were obtained. These improvements were not a cure but a marked relief of symptoms.

It was found, however, that, while levodopa was effective, it produced severe side effects, such as nausea, dizziness, and palpitations. Even when treatment was initiated gradually, it was difficult to balance the benefits against the adverse reactions.

Today the drug is prescribed, in combination form, with carbidopa (as co-careldopa) or benserazide (as co-beneldopa), both of which enhance the effects of levodopa in the brain, in addition to helping to reduce the side effects of levodopa. The drug is taken by mouth and, in severe cases, can be administered in the form of intestinal gel.

INFORMATION FOR USERS

Your drug prescription is tailored for you. Do not alter dosage without checking with your doctor.

How taken/used Tablets, dispersible tablets, capsules, intestinal gel.

Frequency and timing of doses 2–6 x daily with food or milk.

Adult dosage range 125–500mg initially, increased until benefits and side effects are balanced.

Onset of effect Within 1 hour.

Duration of action 2–12 hours.

Diet advice None.

Storage Keep in original container at room temperature out of the reach of children. Store intestinal gel in a refrigerator. Protect from light.

Missed dose Take as soon as you remember. If your next dose is due within 2 hours, take a single dose now and skip the next.

Stopping the drug Do not stop taking the drug without consulting your doctor; stopping the drug may lead to severe worsening of the underlying condition.

Exceeding the dose An occasional unintentional extra dose is unlikely to cause problems. Larger overdoses may cause vomiting or drowsiness. Notify your doctor.

POSSIBLE ADVERSE EFFECTS

Adverse effects are related to the dosage level. At the start of treatment, on a low dosage, side effects are likely to be mild, but they may become more severe as the dosage is increased. Common adverse effects include dark urine, digestive disturbances, abnormal movements, nervousness or agitation, confusion, and hallucinations. Rarer adverse effects include dizziness, fainting, fatigue, sudden sleepiness, and compulsive behaviour. All adverse effects should be discussed with your doctor.

INTERACTIONS

Antidepressant drugs Levodopa may interact with monoamine oxidase inhibitors (MAOIs) to cause a dangerous rise in blood pressure. It may also interact with tricyclic antidepressants.

Iron Absorption of levodopa may be reduced by iron.

Antipsychotic drugs Some of these drugs may reduce the effect of levodopa.

SPECIAL PRECAUTIONS

Be sure to tell your doctor if:

· You have heart problems.

· You have long-term liver or kidney problems.

· You have epilepsy.

· You have had glaucoma.

· You have a peptic ulcer.

· You have diabetes or any other endocrine disorder.

· You have any serious mental illness.

· You are taking other medicines.

Pregnancy Unlikely to be required. Safety not established. Discuss with your doctor.

Breast-feeding Unlikely to be required. May suppress milk production. Discuss with your doctor.

Infants and children Not normally used in children (and rarely given to patients under 25 years).

Over 60 No special problems.

Driving and hazardous work Your underlying condition, as well as the possibility of levodopa causing fainting, dizziness, and sudden sleep episodes, may make such activities inadvisable. Discuss with your doctor.

Alcohol No known problems, although levodopa may enhance the sedative effects of alcohol.

PROLONGED USE

Effectiveness usually declines with time, necessitating increased dosage. Also, the adverse effects become severe at the end of one dose and the onset of another, so that the dosage, frequency, or formulation must be fine-tuned for each individual. Ultimately, other antiparkinsonian drugs may need to be substituted.