Dopamine agonists: Uses, common brands, and safety info

Dopamine agonists, also known as dopamine receptor agonists, are medications prescribed to treat Parkinson’s disease, a neurodegenerative disease that is believed to be caused by low levels of dopamine. Dopamine agonists mimic dopamine in the brain and central nervous system (CNS) to help treat symptoms of Parkinson’s disease, such as involuntary movements or shaking. These medications can also be used to treat restless legs syndrome and hyperprolactinemia, as well as other medical conditions. 

Continue reading to learn more about dopamine agonists, how they work, what they’re used for, and their most common side effects.

Other dopamine agonists

• Dopergin (lisuride)

• Trivastal (piribedil)

• Permax (pergolide mesylate) [discontinued from US market]

What are dopamine agonists?

Dopamine agonists are prescription medications that are mainly used to treat Parkinson’s disease and other movement disorders. They are often used as an alternative to levodopa, a dopamine precursor that helps improve movement-related symptoms of Parkinson’s. While levodopa therapy is an effective treatment of Parkinson’s disease, it can cause involuntary movement side effects (dyskinesia). Dopamine agonists were originally developed to treat Parkinson’s in combination with levodopa, but they are now recommended to be used as initial monotherapy for early Parkinson’s disease due to levodopa’s side effects. As the disease progresses, levodopa therapy may be added on top of treatment with a dopamine agonist. 

Dopamine agonists are often a first-line treatment for Parkinson’s disease and restless legs syndrome. The most commonly prescribed dopamine agonists in the US are pramipexole and ropinirole. Other antiparkinsonian agents include monoamine oxidase B inhibitors, anticholinergics, cholinesterase inhibitors, and amantadine. 

Dopamine agonists come in several different formulations such as oral tablets, extended-release tablets, transdermal patches, and subcutaneous injections. Pramipexole and ropinirole are available as immediate-release and extended-release tablets. Older dopamine agonists like bromocriptine and cabergoline can be given as oral tablets. For those who have trouble taking an oral medication, rotigotine is available as a transdermal patch. Apomorphine is administered as a subcutaneous injection for certain situations, such as “off” periods of motor fluctuations. 

How do dopamine agonists work?

Low dopamine levels are the primary cause of symptoms of Parkinson’s disease. Dopamine is a neurotransmitter involved with several functions of the pancreas, kidney, gastrointestinal tract, and other parts of the body. It is important for sending chemical signals to nerve cells throughout the body, and it works by binding to dopamine receptors on neurons to transmit chemical signals. This neurotransmitter is involved with processes like voluntary muscle movements, blood vessel dilation, inflammation, mood, and memory formation, as well as the regulation of prolactin production and secretion from the pituitary gland.

Dopamine is also heavily involved with the reward system of the brain. Dopamine is linked to feelings of pleasure and motivation, and it can reinforce reward-seeking and compulsive behaviors such as those associated with love, sex, drugs, and gambling. 

There are two types of dopamine receptors: 

1. D1-like dopamine receptors, which include the D1 and D5 receptor subtypes

2. D2-like dopamine receptors, which include the D2 and D3 receptor subtypes, as well as the D4 receptor subtype. 

Dopamine agonists can bind to D1-like and D2-like dopamine receptors and mimic the actions of dopamine. The D1 and D2 receptors are the dopamine receptors primarily involved with movement-related symptoms (tremors) of Parkinson’s disease. D2 receptors are also involved with psychotic symptoms of bipolar disorder and schizophrenia. 

What are dopamine agonists used for?

• Parkinson’s disease

• Restless legs syndrome

• Hyperprolactinemia

Types of dopamine agonists

Ergoline derivatives

The early dopamine agonists used to treat Parkinson’s disease were ergoline derivatives. These ergot-derived dopamine agonists primarily act on D1 and D2 receptors, as well as serotonergic, adrenergic, and other neurotransmitter receptors. They are rarely used to treat Parkinson’s disease today because of an increased risk of scarring in the lungs (pulmonary fibrosis) and heart valves (cardiac valvular fibrosis). Pergolide has been discontinued from the U.S. market because of an increased risk of valvular fibrosis. Examples of ergoline derivatives include cabergoline, bromocriptine, and lisuride. 

Non-ergoline derivatives

Non-ergoline, or non-ergot derived, dopamine agonists are a newer generation of dopamine agonists. They primarily bind to D2 and D3 receptors to help treat movement disorders like Parkinson’s disease and restless legs syndrome. Non-ergoline derivatives are preferred as first-line treatments over ergoline derivatives. Examples of non-ergoline derivatives include pramipexole, ropinirole, apomorphine, rotigotine, and piribedil. 

Who can take dopamine agonists?

Adults

Adult men and women are often prescribed a dopamine agonist for the treatment of Parkinson’s disease or restless legs syndrome. Pramipexole or ropinirole are often recommended as first-line treatments for early or severe Parkinson’s disease. They’re prescribed to manage symptoms and improve quality of life, as well as delay the need for levodopa therapy. Dopamine agonists are also a first-line treatment for restless legs syndrome and hyperprolactinemia in adults. 

Seniors

The incidence of Parkinson’s disease increases with age with only 4% of people diagnosed with Parkinson’s disease before age 50. Therefore, dopamine agonists are often prescribed in older adults. However, the risk of adverse effects may be high in elderly patients, especially if they have kidney or liver problems. Those with kidney problems may not be able to clear the drug as fast from their body, which can increase levels of the drug in the body and increase the risk of side effects. Older people taking dopamine agonists should be monitored for side effects like increased drowsiness, blood pressure changes, and falls. Dosing adjustments may need to be made in older patients. 

Children

The most common dopamine agonists have not been studied for effectiveness or safety in children. However, they may be prescribed off-label by a healthcare provider. For example, dopamine agonists are a first-line treatment for children with hyperprolactinemia. 

Are dopamine agonists safe?

Dopaminergic drugs are typically safe and effective treatments when used as prescribed. The risk of side effects depends on the dosing of the medication. Non-ergoline derivatives are the safest type of dopamine agonists. A healthcare provider that specializes in neurology will be able to help determine whether dopamine agonists may be right for you.

Recalls

No current recalls as of August 2021. 

Restrictions

You should tell your healthcare provider about any medical conditions, especially if you have a history of low blood pressure, sleep disorders, muscle movement disorders, and kidney or liver problems before starting treatment with a dopamine agonist. 

Women who are pregnant or breastfeeding should also consult a healthcare provider before taking a dopamine agonist. Dopamine agonists may affect an unborn baby or transfer into breast milk. 

Alcohol should be avoided while taking a dopamine agonist due to an increased risk of sleepiness. 

Those with a history of pulmonary or valvular fibrosis should not take ergoline derivative dopamine agonists. Those who are allergic to any ingredients in dopamine agonist medicines should avoid taking any dopamine agonist.  

You should also tell your doctor about other medications you may be taking, including prescription medicines, over-the-counter medicines, and herbal supplements. Certain drugs may increase the risk of adverse effects when combined with a dopamine agonist. Monoamine oxidase inhibitors (MAOIs) should not be used with dopamine agonists, and they should be discontinued for at least 14 days before starting a dopamine agonist. Because dopamine agonists can lower blood pressure, they should be used with caution with antihypertensive medicines. Consult a healthcare provider for other possible drug interactions. 

Are dopamine agonists controlled substances?

No, dopamine agonists are not controlled substances.

Common dopamine agonists side effects

The most common side effects of dopamine agonists include:

• Nausea

• Vomiting

• Excessive daytime sleepiness or somnolence

• Sudden sleep episodes, or sleep attacks

• Orthostatic hypotension

• Headache

• Dizziness

• Heart rhythm problems (arrhythmias)

• Constipation

The risk of side effects depends on the daily dose prescribed. Higher doses of dopamine agonists are more likely to cause side effects than lower doses. For this reason, doses are usually titrated, or increased slowly, over time. 

Serious side effects of dopamine agonists may include pulmonary fibrosis, stomach ulcers, swelling in the hands or legs, psychosis, and hallucinations.

Impulse control disorder is another serious side effect of dopamine agonists, and it is often identified by pathological gambling, hypersexuality, binge eating, or compulsive shopping sprees. 

Consult a healthcare provider for other possible side effects.

How much do dopamine agonists cost?

Dopamine agonists are typically available in brand-name and generic forms. Medicare and prescription drug plans will usually cover the most commonly prescribed dopamine agonists. However, you should check with your insurance provider or pharmacist to determine your exact copay for your prescription. Those who are uninsured also have several options to save on dopamine agonist prescriptions. For example, SingleCare provides a prescription discount card that can be used by both insured and uninsured patients to save on their medications.