What Is Carbidopa Levodopa?

Levodopa helps decrease tremors, muscle stiffness and other symptoms of Parkinson's disease, while carbidopa decreases side effects associated with levodopa. These drugs are combined into one medication called Sinemet, also available in generic form.

Dopamine Deficiency

• Dopamine deficiency in the brain may be responsible for many Parkinson's disease symptoms. Taking dopamine does not help these patients, however, because the substance cannot cross the blood-brain barrier. The body can use levodopa to make dopamine, which can cross this barrier.

Levodopa Side Effects

• Levodopa can cause many negative side effects if it becomes active before reaching the brain. These include nausea and vomiting, uncontrollable twitching or jerking, trembling, heart palpitations, confusion and hallucinations.

Carbidopa Purpose

• Carbidopa delays the conversion of levodopa into dopamine until it reaches the brain, thus reducing side effects.

Complications

• About half the patients taking levodopa on its own or combined with carbidopa develop permanent complications, including involuntary movements. Doctors typically avoid prescribing levodopa until no other drugs are effective at treating the patient's symptoms.

Additional Uses

• In addition to reducing symptoms of Parkinson's disease, a combination of carbidopa and levodopa is effective at treating symptoms similar to that disorder, such as those caused by carbon monoxide poisoning, manganese poisoning or encephalitis.