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Home > Drug Category > Parkinson's Disease, Dopamine Agonists > Tasmar and Equivalent

Tasmar (Tolcapone) Information

Tasmar (tolcapone) is a catechol-O-methyltransferase (COMT) inhibitor. It is indicated as an adjunct therapy for the treatment of Parkinson's disease (PD), used only in combination with levodopa and carbidopa. Tolcapone is reserved for patients experiencing motor fluctuations who have not responded adequately to other adjunctive therapies, due to its risk of hepatotoxicity. It works to smooth out the "wearing off" periods that occur when the effect of a levodopa dose begins to fade. Tasmar is taken orally and must always be used alongside levodopa/carbidopa—it is not effective as a standalone treatment.

The mechanism of action of tolcapone involves prolonging levodopa's (the precursor to dopamine) activity in the brain. When levodopa is taken, much of it is broken down in the bloodstream by the enzyme COMT before it can cross the blood-brain barrier. Tolcapone blocks the COMT enzyme in the peripheral bloodstream, preventing the premature breakdown of levodopa. This allows a greater and more sustained amount of levodopa to reach the brain, where it is converted into dopamine. By extending levodopa's half-life, tolcapone increases the "on" time (period of good motor function) for the Parkinson's patient. Tolcapone is unique among COMT inhibitors because it also acts centrally (in the brain) to block the enzyme.

Tasmar Side Effects

Tasmar can cause a range of side effects, many of which are related to its mechanism of action, which increases dopamine levels. Common side effects include excessive involuntary movements (dyskinesia), which may require a reduction in the levodopa dose. Other frequent effects are nausea, vomiting, diarrhea, dizziness, orthostatic hypotension (a drop in blood pressure upon standing), and sleep disturbances such as somnolence or insomnia. The diarrhea associated with Tasmar can be severe and persistent, often leading to discontinuation of the drug. Patients should also be warned about the potential for sudden sleep onset.

However, more serious side effects can occur, necessitating stringent monitoring. If any of the following symptoms are experienced, the patient should stop taking the medication and seek immediate medical attention:

• Hepatotoxicity (Severe Liver Failure) (Boxed Warning): Tasmar has been associated with rare but potentially fatal acute fulminant liver failure. Due to this risk, liver function tests (LFTs) must be monitored frequently (every 2–4 weeks) for the first year of treatment and periodically thereafter.

• Neuroleptic Malignant Syndrome (NMS): A potentially fatal syndrome that can occur, characterized by high fever, severe muscle rigidity, altered mental status, and autonomic instability. This is often associated with the sudden dose reduction or withdrawal of dopaminergic medications like Tasmar.

• Orthostatic Hypotension (Severe): A potentially severe drop in blood pressure upon standing, leading to fainting (syncope), especially at the start of therapy or during dose increases.

• Rhabdomyolysis: Muscle breakdown that can lead to kidney damage, which is rare but has been reported, sometimes occurring in association with NMS.

• Worsening of Dyskinesia: An increase in levodopa effectiveness can lead to severe or debilitating involuntary movements, often requiring immediate adjustment of the levodopa dose.

Tasmar Precautions

Due to the risk of severe, potentially fatal liver injury, Tasmar carries a Boxed Warning and is generally reserved for patients with motor fluctuations who have failed to respond to other adjunctive therapies. Baseline and frequent monitoring of liver enzymes (ALT and AST) is mandatory for all patients taking Tasmar. If liver enzyme levels exceed twice the upper limit of normal, the medication must be discontinued. Tasmar is contraindicated in patients with liver disease, a history of NMS, or non-traumatic rhabdomyolysis. It must be used with caution in patients with severe dyskinesia, as it may worsen the movements; the levodopa/carbidopa dosage usually requires reduction upon initiation of Tasmar. Tasmar has numerous drug interactions with medications metabolized by COMT, and concomitant use with non-selective MAO inhibitors (e.g., phenelzine) is contraindicated due to the risk of hypertension. Abrupt discontinuation of Tasmar should be avoided, as it can precipitate symptoms resembling NMS.

Do I need a prescription to order Tasmar?

Yes, a prescription is required from your physician to order Tasmar.