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What is the most important information I should know about carbidopa?

Carbidopa is only used in combination with levodopa. It has no effect if it is used on its own.

Use caution when driving, operating machinery, or performing other hazardous activities. Carbidopa may cause dizziness or drowsiness. If you experience dizziness or drowsiness, avoid these activities.

What is carbidopa?

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.

What should I discuss with my healthcare provider before taking carbidopa?

Do not take this medication without first talking to your doctor if you have

• taken a monoamine oxidase inhibitor (MAOI) such as isocarboxazid (Marplan), tranylcypromine (Parnate), or phenelzine (Nardil) in the past 2 weeks;

• narrow-angle glaucoma (angle closure glaucoma); or

• malignant melanoma (a type of skin cancer).

Before taking this medication, tell your doctor if you have

• heart disease, high blood pressure, arteriosclerosis, hardening of the arteries, a previous heart attack, or an irregular heartbeat;

• respiratory disease, including asthma and chronic obstructive pulmonary disease (COPD);

• liver disease;
• kidney disease;

• an endocrine (hormonal) disease;

• a stomach or intestinal ulcer;

• wide-angle glaucoma; or

• depression or any other psychiatric disorder.

You may need a dosage adjustment or special monitoring during treatment if you have any of the conditions listed above.

It is not known whether carbidopa will be harmful to an unborn baby. Do not take carbidopa without first talking to your doctor if you are pregnant or could become pregnant during treatment. It is also not known whether carbidopa will be harmful to a nursing infant. Do not take carbidopa without first talking to your doctor if you are breast-feeding a baby.

How should I take carbidopa?

Take carbidopa exactly as directed by your doctor. If you do not understand these directions, ask your pharmacist, nurse, or doctor to explain them to you.

Take each dose with a full glass of water.

Carbidopa must be taken with levodopa to have an effect.

It is important to take carbidopa regularly to get the most benefit.

Your doctor may want you to have blood tests or other medical evaluations during treatment with carbidopa to monitor progress and side effects.

Store carbidopa at room temperature away from moisture and heat.

What happens if I miss a dose?

Take the missed dose as soon as you remember. However, if it is almost time for the next dose, skip the missed dose and only take the next regularly scheduled dose. Do not take a double dose of this medication.

What happens if I overdose?

Seek emergency medical attention if an overdose is suspected.

Symptoms of a carbidopa overdose include muscle spasms or weakness, spasms of the eyelid, nausea, vomiting, diarrhea, an irregular heartbeat, confusion, agitation, hallucinations, and unconsciousness.

What should I avoid while taking carbidopa?

Use caution when driving, operating machinery, or performing other hazardous activities. Carbidopa may cause dizziness or drowsiness. If you experience dizziness or drowsiness, avoid these activities.