National Stroke Foundation


The following drug information is obtained from various newswires, published medical journal articles, and medical conference presentations.


Approval Status:

October 19, 1999

Specific Treatments:

For Parkinson's patients being treated with levodopa therapy who experience end-of-dose "wearing off"

Therapeutic Areas

General Information

This new treatment in the management of idiopathic Parkinson's Disease helps prolong the effects of the levodopa/carbidopa preparations, such as improved motor performance and increased amounts of "on" time (periods of good function and mobility in which a patient is able to perform common daily activities such as walking, speaking, and writing).
Comtan belongs to a class of therapeutic treatments called COMT inhibitors which block the COMT enzyme. When taken with the prescribed levodopa/carbidopa treatment, the inhibitor reduces the breakdown of levodopa before it reaches the brain. As a result, the effects of each levodopa dose are extended and enhanced.

Clinical Results

The effects of Comtan were tested on nearly 700 patients in worldwide, multi-center trials. Compared to a placebo, patients with Parkinson's who took Comtan demonstrated improved motor performance and had significantly increased amounts of "on" time each day. Several important Phase III studies indicated that the benefits were salient for patients who showed deteriorating response to levodopa/carbidopa, particularly in important activities of daily living such as speaking, handwriting, walking and dressing.

Side Effects

Comtan is generally well-tolerated and doesn't require any specific safety monitoring. The most commonly reported side-effects were dyskinesia, nausea, diarrhea, abdominal pain and urine discoloration. A very small percentage of participants in the trials also experienced hallucinations. Dopaminergic side effects like dyskinesia often improved after adjustment of the levodopa dosage.

Mechanism of Action

Entacapone inhibits COMT and alters the plasma pharmokinetics of levodopa. When entacapone is given in conjunction with levodopa and an aromatic amino acid decarboxylase inhibitor, such as carbidopa, plasma levels of levodopa are greater and more sustained than after administration of levodopa and an aromatic amino acid decarboxylase inhibitor alone. It is believed that at a given frequency of levodopa administration, these more sustained plasma levels of levodopa result in more constant dopaminergic stimulation in the brain, leading to greater effects on the signs and symptoms of Parkinson's disease. The higher levodopa levels also lead to increased levodopa adverse effects, sometimes requiring a decrease in the dose of levodopa. (FDA Label)

Additional Information

For more information about Comtan, call 1-888-669-6682.
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