COMT inhibitors (entacapone, opicapone)

COMT inhibitors is the name used to describe a type (class) of Parkinson’s drugs.

How do COMT inhibitors work?

Levodopa can boost the supply of dopamine in your brain. COMT inhibitors can block an enzyme (a protein which makes a chemical reaction happen) that breaks down levodopa medication. This helps it to work more effectively.

When are COMT inhibitors used?

COMT inhibitors do not help to manage the symptoms of Parkinson’s on their own – they have to be used with levodopa.

Your specialist might prescribe them if your dose of levodopa is not working for long enough.

It will also help your levodopa medication to work more smoothly in controlling your symptoms.

Benefits of COMT inhibitors

Helping levodopa work smoothly

COMT inhibitors can help when levodopa is not working for long enough and starts to wear off between doses. They can help to reduce your ‘off’ time, when you have more trouble with your Parkinson’s symptoms. And they increase the amount of ‘on’ time, when your symptoms are more controlled.

If you take levodopa for a long time, you may experience end of dose motor fluctuations when your symptoms are poorly controlled before your next dose is due. If this happens you can take COMT inhibitors with your levodopa medication to ease this issue.

Taking less levodopa

In many cases, you will be able to take a lower dose of levodopa and less often.

Risks and side effects of COMT inhibitors

Coloured urine and diarrhoea

COMT inhibitors will colour your urine a bright reddish orange colour, but this isn’t harmful.

You may experience diarrhoea weeks or months after starting co-careldopa and entacapone (Stalevo, Sastravi, Stanek). If this happens, get in touch with your specialist or Parkinson’s nurse for advice.

Worse levodopa side effects

COMT inhibitors strengthen the effects of levodopa. This can make involuntary movements (dyskinesia) and sickness worse.

If this happens, your specialist or Parkinson’s nurse can reduce your dose of levodopa.

Impulsive and compulsive behaviours

This medication can cause impulsive and compulsive behaviours, which can happen with any Parkinson’s drugs.

Other side effects

The patient information leaflet that comes with your medication will tell you about all of the side effects that you may have.

Some of these side effects include:

• sleeping problems
• loss of appetite
• dizziness
• fainting
• falls
• hallucinations
• headaches
• confusion
• dry mouth
• chest pain
• sleepiness.

If you are allergic to peanuts or soya, make sure you tell your specialist and Parkinson’s nurse as you may not be able to take some COMT inhibitors.

Types of COMT inhibitors

Below are the types of COMT inhibitor drugs. Each drug has a generic (unbranded) name and a branded name.

Entacapone

Entacapone is a COMT inhibitor drug used to manage the symptoms of Parkinson’s. The brand name of entacapone is Comtess.

If you’ve had Parkinson’s for some time and your symptoms get worse between each dose of medication, you may be prescribed entacapone (Comtess). It works to increase how well the levodopa medication you are taking works and stops it from being broken down in the body.

Taking entacapone

The most up-to-date information on the medication you are taking will be on your patient information leaflet. You will find it with your medication packet. Always read it carefully before you start your treatment.

Ask your specialist for detailed advice about how to take entacapone so that it works well for your Parkinson’s. Below we have included information on how to take entacapone (Comtess) medication:

• You should take entacapone (Comtess) tablets at the same time as your co-beneldopa or co-careldopa levodopa medication.
• Entacapone increases how well your co-beneldopa or co-careldopa levodopa medication works. But too much levodopa can cause side effects. So when you start taking entacapone, your specialist or Parkinson’s nurse may need to adjust the amount of levodopa that you take.
• You can take your entacapone medication with or without food.
• When you take your entacapone (Comtess) tablets it may help not to take any medicines or vitamin supplements with iron in them. Iron can mean that less entacapone gets into the parts of the body where it is needed. You may be able to take medicines or vitamin supplements with iron in them 2 to 3 hours after taking entacapone. Talk to your specialist, Parkinson’s nurse or pharmacist for more information about this. 

Co-careldopa and entacapone

Sastravi, Stalevo and Stanek are branded versions of co-careldopa and entacapone medication. This means they combine the levodopa medication co-careldopa with entacapone.

The entacapone helps to make the levodopa part of the drug stronger, which helps to control your symptoms.

Using this combination drug also means that it’s easier for people to take.

Taking co-careldopa and entacapone

You may be prescribed co-careldopa and entacapone (Stalevo, Sastravi and Stanek) if levodopa medication alone is not able to control motor fluctuations you experience at the end of your dose. This is when you go from having good control of your movement symptoms to having less control.

The maximum dose of Stalevo, Sastravi and Stanek medication is usually 7 to 10 tablets, depending on the strength you are prescribed.

Your specialist can advise you on when to take your medication and exactly how much to take.

Tolcapone

Tolcapone is a type of COMT inhibitor. Its brand name is Tasmar. There is a risk of serious liver damage. Because of this, you will need regular blood tests to check the health of your liver.

The risk of serious liver damage is rare. But tolcapone is only used if you can’t take entacapone or opicapone, as no risk of liver damage has been seen with these drugs. Because of this we have not included further information about tolcapone here.

Opicapone

Opicapone is a type of COMT inhibitor medication. Its brand name is Ongentys. Opicapone strengthens your levodopa medication to make it work better than when it is taken alone.

Taking opicapone

The most up-to-date and complete information on your specific drug will be on your patient information leaflet that comes with your medication packet. Always read it carefully before you start your treatment.

For detailed information you should follow the advice of your specialist about how to take opicapone (Ongentys) so that it works well for your Parkinson’s.

You should take opicapone once a day at bedtime. You should do this at least an hour before or after your levodopa medication.

Because opicapone is taken with levodopa to make it work well and reduce side effects, your healthcare professional may need to adjust the amount of levodopa you take. You should discuss this with them.