Tolcapone Review Article
Tolcapone (Tasmar) is used to treat patients with Parkinson’s disease. Tasmar is a medicine that contains the active substance tolcapone.
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Tolcapone is available as hexagonal tablets (pale yellow: 100 mg; yellow-orange: 200 mg).
What is Tolcapone (Tasmar) used for?
Tasmar is used to treat patients with Parkinson’s disease. Parkinson’s disease is a progressive brain disorder that causes shaking, slow movement and muscle stiffness. Tasmar is used together with other standard treatments for Parkinson’s disease (either a combination of levodopa and benserazide or a combination of levodopa and carbidopa) when the patients have ‘fluctuations’ towards the end of the period between two doses of their standard combination. Fluctuations are linked with a reduction in the effects of levodopa, when the patient experiences sudden switches between being ‘on’ and able to move, and being ‘off’ and immobile. Tasmar is only used when patients do not respond, or cannot take other medicines of the same type.
How is Tasmar used?
Tasmar treatment should only be prescribed and supervised by a doctor who has experience in the management of advanced Parkinson’s disease. Tasmar is always given with levodopa and benserazide or with levodopa and carbidopa. The recommended dose is 100 mg three times a day. The tablets should be swallowed whole. When patients add Tasmar to their existing anti-Parkinson’s disease medication, they need to be made aware that they may experience some of the side effects of levodopa, although these can often be reduced by lowering the dose of levodopa. The dose of Tasmar may be increased to 200 mg three times a day but only when the benefit expected outweighs the risk of liver injury. If after three weeks, no substantial benefit has been seen, treatment with Tasmar should be stopped. Doctors should check the patient’s liver before starting treatment with Tasmar and then regularly during treatment. Treatment should be stopped in patients who develop liver problems.
How does Tasmar work?
In patients with Parkinson’s disease, the cells in the brain that produce the neurotransmitter dopamine begin to die and the amount of dopamine in the brain decreases. The patients then lose their ability to control their movements reliably. The active substance in Tasmar, tolcapone, works to restore the levels of dopamine in the parts of the brain that control movement and co-ordination. It only works when it is taken with levodopa, a copy of the neurotransmitter dopamine that can be taken by mouth. Tolcapone blocks an enzyme that is involved in the breakdown of levodopa in the body called catechol-O-methyl transferase (COMT). As a result, levodopa remains active for longer. This helps to improve the signs and symptoms of Parkinson’s disease, such as stiffness and slowness of movement.
How has Tasmar been studied?
Tasmar was originally studied in a total of 594 patients, in two 13-week studies and one six-week study. All of the studies compared the effectiveness of adding Tasmar with that of adding placebo (a dummy treatment) to the patient’s existing medication (levodopa and either carbidopa or benserazide). The main measure of effectiveness was how long the patients spent in the ‘off’ or in the ‘on’ state. Tasmar has also been studied in a ‘switch’ study in 150 patients. These patients were already receiving a combination of levodopa and entacapone (another medicine that blocks COMT). The study compared the effectiveness of continuing with entacapone or switching to Tasmar. The main measure of effectiveness was the number of patients with an increase in ‘on’ time of one hour or more, during the three weeks following the switch.
What benefit has Tasmar shown during the studies?
The initial studies showed that Tasmar was more effective than placebo. There was a reduction of about 20 to 30% in ‘off’ time in patients taking Tasmar. In the switch study, more patients responded to Tasmar (53%; 40 out of 75) than to entacapone (43%; 32 out of 75).
What is the risk associated with Tasmar?
The most common side effects with Tasmar (seen in more than 1 patient in 10) are nausea (feeling sick), loss of appetite, diarrhoea, dyskinesia (uncontrollable movements), dystonia (muscle spasms), headache, dizziness, sleep disorders, excessive dreaming, somnolence (sleepiness), confusion, hallucination (seeing things that are not there) and orthostatic complaints (dizziness on standing). Tasmar can cause liver injury, which can be fatal in rare cases. Doctors should monitor patients very carefully during treatment. For the full list of all side effects reported with Tasmar, see the Package Leaflet. Tasmar should not be used in patients who may be hypersensitive (allergic) to tolcapone or any of the other ingredients. It must not be used in patients with:
signs of liver disease or increased liver enzymes;
phaeochromocytoma (a tumour of the adrenal gland);
a history of neuroleptic malignant syndrome (a dangerous nervous disorder usually caused by antipsychotic medicines), rhabdomyolysis (breakdown of muscle fibres) or hyperthermia (heat stroke);
Why has Tasmar been approved?
The Committee for Medicinal Products for Human Use (CHMP) decided that Tasmar’s benefits are greater than its risks in combination with levodopa/benserazide or levodopa/carbidopa for use in patients with levodopa-responsive idiopathic Parkinson’s disease and motor fluctuations, who failed to respond to or are intolerant of other COMT inhibitors. The Committee recommended that Tasmar be given marketing authorisation.
Tolcapone Review Article