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COMT inhibitors - Parkinson's drugs

Stalevo - combines levodopa, carbidopa and entacaponeCOMT inhibitors are used to treat the symptoms of Parkinson's

COMT inhibitors do not help Parkinson’s on their own – they have to be used with levodopa

COMT inhibitors reduce the symptoms by slowing the destruction of levodopa and prolonging its effect.

The generic drug names and brand names are:

  • Entacapone (Comtess®)
  • Tolcapone (Tasmar®)
  • Levodopa/carbidopa/entacapone (Stalevo®)

Entacapone (Comtess®)

Entacapone (Comtess®) is taken with levodopa or tolcapone.

It is effective from the first dose and the individual should feel the benefit within a day or two.

See the Comtess Medicine Guide for independent, up to date information about this medicine.

Tolcapone (Tasmar®)

Tolcapone was withdrawn from the UK in 1998 due to its effect on liver function. In 2005 prescribing procedures were heavily modified and tolcapone was reintroduced.

To avoid any potential risks, only physicians experienced in the management of advanced Parkinson's will be able to prescribe tolcapone. Patients must also undergo regular medical checks.

See the Tolcapone Medicine Guide for independent, up to date information about this medicine.

Stalevo

Stalevo is a combination drug to treat Parkinson's, which contains levodopa, carbidopa and entacapone in one tablet.

See the Stalevo Medicine Guide for independent, up to date information about this medicine.

Advantages of COMT inhibitors

When used with levodopa, COMT inhibitors can reduce the daily 'off' time and increase the 'on' time. In many cases, the levodopa dose and dosing frequency can also be reduced.

The terms 'on/off' or 'motor fluctuations' refers to the period of time, often years, when people may find that the smooth and even control of symptoms that their drugs once gave them is no longer dependable.

Read more in our motor fluctuations in Parkinson's information sheet

Some disadvantages of COMT inhibitors

These drugs can increase the side effects caused by levodopa, notably dyskinesias (unwanted involuntary movements), nausea and vomiting.

If these side effects increase after starting the drug, people should raise the issue with their healthcare professional as reducing the levodopa dose can often help.

Be aware that other drugs (for Parkinson's or other conditions) can affect the action of COMT inhibitors. The combination of apomorphine and entacapone needs careful supervision.

Other reported side effects of COMT inhibitors include abdominal pain, diarrhoea and discoloured urine.

Read more in our drug treament of Parkinson's booklet

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