Indications
Carbidopa is used together with Levodopa (in the same tablet) to treat the symptoms of Parkinson’s disease and parkinsonism, such as shaking (tremor), stiffness and slowness of movement.
How It Works
Parkinson’s disease is linked to a shortage of dopamine, a chemical messenger in the brain. Levodopa is turned into dopamine in the brain. Carbidopa stops Levodopa from being broken down in the rest of the body, so more of it reaches the brain. This means a lower dose of Levodopa can be used and causes less nausea.
Dosage and Administration
The dose is set by the doctor for each person, as prescribed. Treatment is usually started at a low dose, often one tablet of 25 mg carbidopa with 100 mg levodopa three times a day, and adjusted slowly according to response and side effects.
- Take at regular times each day.
- It works best taken about 30 minutes before meals; a large protein-rich meal can reduce its effect. If it upsets your stomach, take it with a light, low-protein snack.
- Do not stop taking it suddenly or change the dose without your doctor.
Interactions
- Older non-selective MAOIs (a type of antidepressant) must not be taken with it, and must be stopped at least 14 days before.
- Antipsychotic medicines such as Haloperidol and Risperidone, and Metoclopramide, can reduce its effect.
- Iron supplements reduce its absorption; take them at a different time.
- Blood pressure medicines can cause a larger fall in blood pressure on standing.
- Selegiline and Rasagiline increase its effect; the doctor may lower the dose.
- Phenytoin and Isoniazid may reduce its effect.
Contraindications
- Allergy to carbidopa, levodopa or any ingredient.
- Taking a non-selective MAOI in the last 14 days.
- Narrow-angle glaucoma.
- Undiagnosed suspicious skin lesions or a history of melanoma (a skin cancer).
Side Effects
Common: nausea, loss of appetite, dizziness on standing, sleepiness, uncontrolled twisting or jerking movements (dyskinesia), vivid dreams, confusion, and dark urine or sweat (harmless).
Some people develop strong urges such as gambling, shopping, eating or sexual urges; tell your doctor if you or your family notice this.
Get urgent medical help for hallucinations or severe confusion, falling asleep suddenly without warning, fainting, chest pain or irregular heartbeat, black stools or vomiting blood, high fever with stiff muscles, or swelling of the face or difficulty breathing.
Pregnancy and Lactation
Pregnancy: there is limited information; use only if the doctor decides the benefit is greater than the risk. Breastfeeding: Levodopa can reduce milk supply and passes into milk, so breastfeeding is generally not advised.
Precautions and Warnings
Do not drive or use machines if you feel sleepy or have had sudden sleep episodes. Stand up slowly. Tell your doctor if you have heart disease, lung disease or asthma, a stomach ulcer, liver or kidney disease, glaucoma, or depression or other mental health problems. Stopping it suddenly can cause a serious reaction with high fever and stiffness. Have regular check-ups, including skin checks.
Overdose
Too much can cause severe uncontrolled movements, agitation, confusion, an irregular heartbeat and low blood pressure. Seek emergency medical help.
Therapeutic Class
Anti-Parkinson medicine (dopamine precursor with a decarboxylase inhibitor).
Storage
Store below 30°C in a dry place, away from light and out of the reach of children.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.