Carbidopa

Carbidopa is used with another medicine called levodopa to treat the symptoms of Parkinson's disease (stiffness, tremors, spasms, poor muscle control). Symptoms of Parkinson's disease may be caused by low levels of a chemical called dopamine (DOE pa meen) in the brain.

Levodopa is converted to dopamine in the brain. Carbidopa helps prevent the breakdown of levodopa before it can reach the brain and take effect.

Carbidopa is only used in combination with levodopa. Carbidopa has no effect when used alone.

Carbidopa is also used with levodopa to treat muscle symptoms similar to Parkinson's disease that are caused by certain drugs such as chlorpromazine (Thorazine), fluphenazine (Prolixin), perphenazine (Trilafon), and others.

Carbidopa may also be used for purposes not listed in this medication guide.

You should not use carbidopa if you have narrow-angle glaucoma.

Do not use carbidopa with levodopa if you have used an MAO inhibitor in the past 14 days. A dangerous drug interaction could occur. MAO inhibitors include isocarboxazid, linezolid, methylene blue injection, phenelzine, rasagiline, selegiline, tranylcypromine, and others.

You should not use carbidopa if you are allergic to it, or if you have:

• narrow-angle glaucoma.

Do not use carbidopa with levodopa if you have used an MAO inhibitor in the past 14 days. A dangerous drug interaction could occur. MAO inhibitors include isocarboxazid, linezolid, methylene blue injection, phenelzine, rasagiline, selegiline, tranylcypromine, and others.

To make sure carbidopa is safe for you, tell your doctor if you have:

• a history of depression, mental illness, or psychosis;
• a history of suicidal thoughts or actions; or
• if you also take blood pressure medication.

FDA pregnancy category C. It is not known whether carbidopa will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using this medicine.

It is not known whether carbidopa passes into breast milk or if it could harm a nursing baby. You should not breast-feed while using this medicine.

Carbidopa is not approved for use by anyone younger than 18 years old.

Avoid taking iron supplements or eating a diet that is high in protein (protein sources include meat, eggs, and cheese). These things can make it harder for your body to digest and absorb carbidopa and levodopa. Talk with your doctor or nutrition counselor about the best foods to eat while you are taking this medication.

This medicine may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert. Avoid getting up too fast from a sitting or lying position, or you may feel dizzy. Get up slowly and steady yourself to prevent a fall.

Other drugs may interact with carbidopa, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using.

Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended.

Take both carbidopa and levodopa at the same time.

If you already take levodopa but have never taken carbidopa before, start taking both medicines at least 12 hours after you last took levodopa by itself.

Use carbidopa with levodopa regularly to get the most benefit. Get your prescription refilled before you run out of medicine completely.

While using this medicine, you may need frequent blood tests. Your heart, kidney function, and liver function may also need to be checked.

It may take up to several weeks of using carbidopa with levodopa before your symptoms improve. For best results, keep using the medication as directed. Talk with your doctor if your symptoms do not improve after a few weeks of treatment. Also tell your doctor if the effects of this medication seem to wear off quickly in between doses.

Do not stop using carbidopa suddenly, or you could have unpleasant withdrawal symptoms. Ask your doctor how to safely stop using this medicine.

This medicine can cause unusual results with certain medical tests. Tell any doctor who treats you that you are using carbidopa with levodopa.

Store at room temperature away from moisture and heat.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

No reports of overdose with LODOSYN have been received. Management of overdosage with carbidopa is the same as that with levodopa or carbidopa-levodopa preparations.

In the event of overdosage, general supportive measures should be employed, along with immediate gastric lavage. Intravenous fluids should be administered judiciously, and an adequate airway maintained. Electrocardiographic monitoring should be instituted and the patient carefully observed for the development of arrhythmias; if required, appropriate antiarrhythmic therapy should be given. The possibility that the patient may have taken other drugs as well as LODOSYN should be taken into consideration. To date, no experience has been reported with dialysis; hence, its value in overdosage is not known. Pyridoxine is not effective in reversing the actions of LODOSYN.

Based on studies in which high doses of levodopa and/or carbidopa were administered, a significant proportion of rats and mice given single oral doses of levodopa of approximately 1500-2000 mg/kg are expected to die. A significant proportion of infant rats of both sexes are expected to die at a dose of 800 mg/kg. A significant proportion of rats are expected to die after treatment with similar doses of carbidopa. The addition of carbidopa in a 1:10 ratio with levodopa increases the dose at which a significant proportion of mice are expected to die to 3360 mg/kg.

Carbidopa is used with levodopa to treat Parkinson's disease. Parkinson's disease is believed to be related to low levels of a chemical called dopamine (DOE pa meen) in the brain. Levodopa (Dopar, Larodopa) is turned into dopamine in the body. Carbidopa is used with levodopa to prevent the breakdown (metabolism) of levodopa before it can reach the brain and take effect. Carbidopa is only effective if it is taken with levodopa. It has no effect if it is used alone.

Carbidopa is used with levodopa to treat the stiffness, tremors, spasms, and poor muscle control of Parkinson's disease. These medications are also used to treat the same muscular conditions when they are caused by drugs such as chlorpromazine (Thorazine), fluphenazine (Prolixin), perphenazine (Trilafon), and others.

Carbidopa may also be used for purposes other than those listed in this medication guide.

Usual Adult Dose for Parkinsonian Tremor:

Patients on carbidopa-levodopa therapy requiring additional carbidopa:
Initial dose: 25 mg orally with the first dose of carbidopa-levodopa each day
Maintenance dose: Additional doses of 12.5 mg or 25 mg may be given with each dose of carbidopa-levodopa
Maximum dose: 200 mg orally per day

Patients requiring individual titration of carbidopa and levodopa:
Initial dose: 25 mg orally three to four times a day, given at the same time as levodopa
Maximum dose: 200 mg orally per day

Comments:
-In patients already on levodopa, allow 12 hours between the last dose of levodopa and the initiation of therapy with carbidopa and levodopa.

Uses: With carbidopa-levodopa or with levodopa in the treatment of symptoms of idiopathic Parkinson's disease (paralysis agitans), postencephalitic parkinsonism, and symptomatic parkinsonism

For all patients taking carbidopa:

• If you have an allergy to carbidopa or any other part of this medicine.
• If you are allergic to any drugs like this one, any other drugs, foods, or other substances. Tell your doctor about the allergy and what signs you had, like rash; hives; itching; shortness of breath; wheezing; cough; swelling of face, lips, tongue, or throat; or any other signs.
• If you have glaucoma.
• If you have taken certain drugs used for low mood (depression) like isocarboxazid, phenelzine, or tranylcypromine or drugs used for Parkinson's disease like selegiline or rasagiline in the last 14 days. Taking carbidopa within 14 days of those drugs can cause very bad high blood pressure.
• If you are taking another drug that has the same drug in it.
• If you are breast-feeding or plan to breast-feed.

Children:

• If the patient is a child. Do not give this medicine to a child.

This is not a list of all drugs or health problems that interact with carbidopa.

Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take this medicine with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.

If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

May be taken with meals to decrease GI upset.

Store at room temperature of 25°C (77°F); excursions permitted to 15°C to 30°C (59°F to 86°F).

False-positive reaction for urinary glucose with Clinitest®; false-negative reaction using Clinistix®; false-positive urine ketones with Acetest®, Ketostix®, Labstix®

Adverse reactions are associated with concomitant administration with levodopa.

Cardiovascular: Cardiac arrhythmia, chest pain, edema, flushing, hypertension, hypotension, myocardial infarction, orthostatic hypotension, palpitation, phlebitis, syncope

Central nervous system: Abnormal dreams, abnormal gait, agitation, anxiety, ataxia, confusion, decreased mental acuity, delusions, dementia, depression (with or without suicidal tendencies), disorientation, dizziness, drowsiness, euphoria, extrapyramidal reaction, falling, fatigue, glossopyrosis, hallucination, headache, Horner's syndrome, impulse control disorder, insomnia, malaise, memory impairment, nervousness, neuroleptic malignant syndrome, nightmares, numbness, on-off phenomenon, paranoia, paresthesia, pathological gambling, peripheral neuropathy, psychosis, seizure (causal relationship not established), trismus

Dermatologic: Alopecia, bulla, diaphoresis, discoloration of sweat, skin rash

Endocrine & metabolic: Abnormal lactate dehydrogenase, glycosuria, hot flash, hyperglycemia, hypokalemia, increased libido (including hypersexuality), increased uric acid, weight changes

Gastrointestinal: Abdominal distress, abdominal pain, anorexia, bruxism, constipation, diarrhea, discoloration of saliva, duodenal ulcer, dysgeusia, dyspepsia, dysphagia, flatulence, gastrointestinal hemorrhage, heartburn, hiccups, nausea, sialorrhea, sore throat, vomiting, xerostomia

Genitourinary: Priapism, proteinuria, urinary frequency, urinary incontinence, urinary retention, urinary tract infection, urine discoloration

Hematologic & oncologic: Abnormal Coombs' test, agranulocytosis, anemia, decreased hematocrit, decreased hemoglobin, hemolytic anemia, leukopenia, malignant melanoma, thrombocytopenia

Hepatic: Abnormal alanine aminotransferase, abnormal alkaline phosphatase, abnormal aspartate transaminase, abnormal bilirubin levels, abnormal lactate dehydrogenase

Hypersensitivity: Angioedema, hypersensitivity reaction (bulla, IgA vasculitis, pruritus, urticaria)

Neuromuscular & skeletal: Back pain, dyskinesia (including choreiform, dystonic, and other involuntary movements), leg pain, muscle cramps, muscle twitching, shoulder pain, tremor, weakness

Ophthalmic: Blepharospasm, blurred vision, diplopia, mydriasis, oculogyric crisis (may be associated with acute dystonic reactions)

Renal: Increased blood urea nitrogen, increased serum creatinine

Respiratory: Cough, dyspnea, hoarseness, upper respiratory tract infection

A decision should be made to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother. Excreted into human milk: Unknown The effects in the nursing infant are unknown.