Tasmar (tolcapone) for Parkinson’s disease
Fact-checked by What is Tasmar for Parkinson’s disease?
Tasmar (tolcapone) is an approved oral therapy used as an add-on to control the symptoms of Parkinson’s disease in certain people who are experiencing symptom fluctuations on levodopa and carbidopa.
Parkinson’s occurs when nerve cells that produce dopamine, a messenger molecule, gradually die off. This results in a variety of motor and nonmotor symptoms, because dopamine plays a key role in many brain processes.
A standard treatment for Parkinson’s is levodopa, a precursor molecule that’s converted to dopamine inside the brain. Over time, however, the medication often becomes less effective, leading to off episodes in which motor symptoms temporarily worsen — called motor fluctuations — between doses.
To make levodopa more effective, it’s often combined with carbidopa, which blocks the DOPA decarboxylase (DDC) enzyme that normally converts levodopa to dopamine outside the brain. This helps more levodopa reach the brain and exert a therapeutic effect.
If the combination of levodopa and carbidopa is not sufficient for symptom control, doctors may prescribe Tasmar. A COMT inhibitor, Tasmar blocks catechol-O-methyltransferase (COMT), an enzyme that rapidly breaks down circulating levodopa. This helps further increase the amount of levodopa available to the brain, enhancing symptom control.
Brand-name Tasmar is marketed in the U.S. by Bausch Health, while Viatris sells it in the European Union. Generic versions of Tasmar, which contain the same active ingredient, are also available.
Therapy snapshot
| Brand name | Tasmar |
| Chemical name | Tolcapone |
| Usage | Used as an add-on to levodopa and carbidopa therapy to ease symptoms in Parkinson’s |
| Administration | Oral tablets |
Who can take Tasmar?
In the U.S., Tasmar is approved as an add-on to levodopa and carbidopa for the treatment of signs and symptoms of idiopathic Parkinson’s, where the disease has no known cause.
The prescribing information for Tasmar carries a boxed warning for the risk of severe liver injury, including liver failure resulting in death. Because of this risk of Tasmar liver toxicity, it should only be used in patients who are experiencing symptom fluctuations and are not responding satisfactorily to or are not candidates for other add-on therapies.
Tasmar is also contraindicated, or should not be used, by individuals who have:
- preexisting liver disease
- previously discontinued Tasmar due to treatment-related liver injury
- a known allergy to the medication or any of its ingredients
- a history of certain serious reactions potentially related to the medication, including nontraumatic rhabdomyolysis, or muscle tissue breakdown, high fever, and confusion
The medication is also not typically recommended for people who are taking nonselective monoamine oxidase (MAO) inhibitors, a type of antidepressant, or those who have a major psychotic disorder.
Use of Tasmar alongside prescribed MAO-B inhibitors, a type of Parkinson’s medication, is usually safe.
Tasmar is also approved in the EU as an add-on to levodopa plus a DDC inhibitor (carbidopa or benserazide) for people who have not responded to or cannot take other COMT inhibitors.
How is Tasmar administered?
Tasmar is available as oral tablets, taken with or without food. The recommended Tasmar dosage is 100 mg, taken three times daily — the first with the first dose of levodopa and carbidopa, and the second and third about six and 12 hours later.
If this regimen is ineffective, doctors may recommend increasing the dose to 200 mg, taken three times daily, but this should be done cautiously because of the risk of liver injury. If no benefit is observed after three weeks on the higher dosage, Tasmar should be discontinued.
Some individuals may require adjustments to their daily levodopa dose while using Tasmar. The medication is also compatible with both immediate-release and sustained-release formulations of levodopa and carbidopa.
Tasmar in clinical trials
Tasmar’s regulatory approvals were supported by three clinical trials that evaluated the oral therapy as an add-on to levodopa-based regimens. In all three studies, participants were randomly assigned to receive a placebo or Tasmar, at the 100 or 200 mg dose, three times daily.
Two of the studies involved individuals experiencing motor fluctuations despite optimized levodopa therapy, who were treated for three months. Data from these studies showed that relative to the placebo, Tasmar was associated with:
- a decrease in average daily off time, although the more effective dose differed between the two studies
- significant reductions in mean daily levodopa dose
- improvements in certain measures of Parkinson’s symptoms and overall functioning
The third study lasted six months and involved individuals without motor fluctuations who were taking levodopa and carbidopa. The results showed:
- the average daily levodopa dose was increased in the placebo group and decreased with either dose of Tasmar, with the differences being statistically significant
- measures of activities of daily living and motor function were improved significantly with both doses of Tasmar compared with the placebo group
Tasmar side effects
The most common side effects of Tasmar observed in clinical trials were:
- uncontrolled, involuntary movements, known as dyskinesia
- nausea
- diarrhea
- vomiting
- loss of appetite
- a sleep disorder
- urine discoloration
- drowsiness
- hallucinations
- uncontrollable muscle contractions, known as dystonia
- sweating
Dyskinesia is a side effect of levodopa that Tasmar may exacerbate. Adjusting the levodopa dosage can sometimes help resolve or ease these problems. Diarrhea may, in some cases, be severe and require treatment discontinuation.
According to the boxed warning, doctors and patients should follow liver monitoring guidelines while using Tasmar, including the use of regular lab tests. Other signs of liver injury may include persistent nausea, fatigue or lethargy, appetite loss, yellowing of the skin or eyes, dark urine, itching, or pain in the upper right abdomen.
If any of these occur, patients should inform their care provider promptly. Any indicators of liver harm mean the medication should be stopped and usually cannot be restarted.
The prescribing label also includes warnings and precautions for other potentially serious side effects, including:
- excessive drowsiness and falling asleep during daily activities
- low blood pressure, particularly when standing up (orthostatic hypotension), and faintingÂ
- new or worsening hallucinations and psychotic-like behavior, particularly in the first six months
- impulse control challenges and compulsive behavior
The label holds a warning for rare, severe side effects that don’t have a well-established relationship to the medication. These include rhabdomyolysis, bloody urine, fever and confusion with medication withdrawal, and internal scarring. Certain skin cancers may also occur. Doctors may recommend monitoring for signs of these conditions, especially when withdrawing from regular Tasmar use.
COMT is involved in the breakdown of drugs besides levodopa, and these medications may interact with Tasmar. Individuals should inform their healthcare team of all substances they are using.
Parkinson's News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.
