Dopamine agonist drugs are one of the main ways to treat Parkinson's symptoms.
Dopamine agonist drugs act like dopamine to stimulate your nerve cells.
How do dopamine agonists work?
Dopamine is a chemical messenger made in the brain. The symptoms of Parkinson’s appear when dopamine levels become too low.
This is because many of the cells in your brain that produce dopamine have died or are dying.
Unfortunately, taking dopamine as a drug doesn’t help, as it can’t cross into your brain where it’s needed. Doctors can get around this by using other treatments.
One treatment option is to use levodopa, which is converted into dopamine in the brain. Another approach is to use dopamine agonist drugs, which act like dopamine to stimulate your nerve cells.
When are dopamine agonists used?
Dopamine agonists are used at all stages of Parkinson’s.
You might take them on their own or alongside levodopa to help the levodopa work better.
Treatment with dopamine agonists has to be started carefully. The dose is gradually increased until you and your specialist or Parkinson’s nurse are happy that your symptoms are under control.
What types of dopamine agonists are there?
Some dopamine agonists are now available as one-a-day tablets, which can be a convenient option for people.
- Mirapexin (tablets)
- Mirapexin prolonged release (prolonged release tablets)
- Unbranded (tablets)
- Adartrel (tablets)
- Ralnea XL (prolonged release tablets)
- Requip (tablets)
- Requip XL (prolonged release tablets)
- Spiroco XL (prolonged release tablets)
- Ipinnia XL (prolonged release tablets)
- Neupro (skin patch)
- APO-go PEN (pre-filled pen for intermittent injection)
- APO-go PFS (pre-filled syringe for infusion. Can be used with a continuous infusion pump)
- Unbranded (tablets)
- Parlodel (tablets, capsules)
- Unbranded (tablets)
- Cabaser (tablets)
- Unbranded (tablets)
What are prolonged release drugs?
Controlled or prolonged release drugs let the dopamine agonists enter your body slowly instead of all at once.
What is a skin patch (Neupro)?
A skin patch (Neupro) may be useful if you have trouble swallowing tablets.
The patch should be held in place for 30 seconds, but left on for 24 hours.
It may cause a skin reaction, such as reddening or itching, but this is usually mild or moderate. It should only affect the area of skin where the patch has been and will normally disappear a few hours when you remove the patch. Moving the patch to a different part of your body every day will help to avoid irritation.
Some, but not all, patches may need to be stored in a refrigerator – check the instructions included with your medication or speak to your pharmacist.
How do injections and infusion pumps (Apomorphine) work?
Apomorphine is a strong dopamine agonist that is given by injection or infusion pump.
It is saved for people with more advanced Parkinson’s who do not respond as well to oral drug treatments, or when most oral drug treatments become less effective or stop working. If you continue to have unpredictable changes in your symptoms that aren’t controlled by other Parkinson’s medications, apomorphine may help.
Apomorphine injections are taken in a similar way to insulin for diabetes. There is a ready-to-use injection pen that works within 5-10 minutes and is often used as a ‘rescue’ measure. This is very useful if you have a sudden ‘off’ period.
If you need more than 7-10 injections a day, you may be changed to a syringe driver. This is a small, battery-driven pump that delivers a continuous dose of medication from a syringe through a needle under the skin.
Ideally, apomorphine will be started in hospital, under the guidance of a specialist or Parkinson’s nurse. Once you are settled on this treatment, you and your carer (if you have one) can be trained in how to use it. If you or a carer are unable to do this, district nurses will be able to help you with this treatment.
APO-go nurse advisors can also start you on treatment. They are registered general nurses with specialist experience in APO-go injections and infusions, as well as the general management of Parkinson’s.
Benefits of dopamine agonists
Delaying levodopa treatment
Dopamine agonists may be an effective treatment for several years when used alone. However, this will not be the case for everyone.
Lowers levodopa needs
Taking dopamine agonists may mean you can take lower doses of levodopa as your condition progresses. This can reduce the risk of experiencing involuntary movements (dyskinesia) or reduce how severe they are.
Fewer movement problems
Your symptoms may be controlled for longer than is usually the case with levodopa. You may also be less prone to long-term side effects such as dyskinesia.
Helping levodopa work better
Dopamine agonists can also be taken with levodopa, at all stages of Parkinson’s. They can help when the effect of levodopa wears off or doesn’t work as well.
Dopamine agonists may help to smooth out the ‘on/off’ effect that you may have with levodopa.
Fewer tablets to take (in some cases)
There are now some once-daily preparations that could make a big difference by reducing the number of tablets you need to take. But this option may not suit everyone.
Positive effects on non-movement symptoms
Risks and side effects of dopamine agonists
Some of the older dopamine agonists increase the risk of heart problems. As a group, these are known as the ‘ergot’ types and they include bromocriptine, pergolide and cabergoline. Because of this risk, these Parkinson’s drugs are not commonly used.
All newer dopamine agonists are non-ergot in type. These are apomorphine, pramipexole, ropinirole and rotigotine. They have not been associated with an increased risk of heart damage. Doctors prefer to use these if possible.
Sleepiness and fainting
Dopamine agonist drugs can make you feel very sleepy, faint or dizzy. This is most likely to happen when you start taking the drugs. Once a stable dose is reached, this effect often wears off.
Sudden onset of sleep, without any warning, has been reported. If this happens, it’s important that you tell your specialist or Parkinson’s nurse.
If you are having apomorphine injections, soreness or nodules can develop at the place where the needle enters your skin.
If this happens, do not stop the treatment, but make sure you get advice from your specialist or Parkinson’s nurse.
It is important to change the injection site each time to give your skin a chance to heal. Simple massage, silicone gel patches or ultrasound can help to reduce any nodules that form.
other side effects
The patient information leaflet that comes with your medication will tell you the full range of side effects that you may experience.
Some of the possible side effects include:
- nausea - Apomorphine can cause severe short-term nausea, so you may also be given an anti-sickness drug called domperidone (Motilium). It needs to be started at least two days before your apomorphine treatment begins, and may be gradually reduced over time
- impulsive and compulsive behaviour
- low blood pressure (hypotension)
- psychological problems
- movement problems
Find out more about the side effects of Parkinson's drugs.