Tasmar (tolcapone) is used in combination with carbidopa and levodopa to treat Parkinson’s disease symptoms such as muscle spasms and stiffness and poor muscle control.

Doctors usually prescribe it to people who are already taking carbidopa and levodopa but whose symptoms have failed to respond to those therapies.

How Tasmar works

It is a dopaminergic medicine — or one that promotes the activity of the neurotransmitter dopamine, which helps regulate movement.

Levodopa relieves Parkinson’s symptoms as it is converted into dopamine, a process that increases dopamine levels in the brain. And Tasmar increases levodopa’s effectiveness.

It does this by keeping levodopa in the blood rather than allowing it to be transformed into the metabolite 3-OMD. A metabolite is a substance produced as a result of metabolism, or the conversion of food to energy. And 3-OMD, or 3-methoxy-4-hydorcy-L-phenylalanine, is one of the main metabolites of levodopa.

The way that Tasmar keeps levodopa in the blood is to block an enzyme named dopa-decarboxylase that is responsible for breaking down levodopa before it reaches the brain. Scientists have linked high blood levels of 3-OMD with levodopa being less effective than it could be in alleviating Parkinson’s symptoms.

Tasmar doubles the amount of levodopa in the blood that can be used to combat Parkinson’s, scientists say.

Tasmar in clinical trials

Tasmar improves the effectiveness of Parkinson’s treatments and reduces the severity of symptoms, according to clinical trials. It also reduces the diseases’s off time by 20-30 percent. Off time is the period when a medication wears off and symptoms reappear. And it increases on time by a similar percentage.

Another clinical trial (NCT00906828) compared Tasmar with Comtan (entacapone) in 150 Parkinson’s patients who were having at least three hours of off time per day while taking oral levodopa.

The primary objective of the study was to see how many patients could increase their on time by at least an hour a day by taking Tasmar.

One of the secondary objectives was to see how many participants achieved moderate or marked improvement in their symptoms. Another secondary objective was to see how many patients achieved both an hour of on and time and improvements in their symptoms.

Forty of the 75 participants who took Tasmar achieved an additional hour or longer of on time, compared with 32 from the Comtan group. The number of those who achieved moderate or marked improvement in symptoms and improvements in both objectives was also greater in the Tasmar group.

Other details

Tasmar must be used in combination with carbidopa and levodopa. It should be taken orally three times a day, with the first dose taken with carbidopa and levodopa. The second dose of Tasmar should be taken six hours later, and the third dose 12 hours later.

It may cause liver damage, so regular blood tests are required to monitor liver function. These should be done every two to four weeks in the first six months of treatment and then as deemed necessary by the doctor.

Getting off Tasmar can lead to withdrawal symptoms, so it should not be stopped suddenly.

Common side effects include drowsiness, mild diarrhea, sleep problems, and more sweating.

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