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Dopamine Agonists

These medications stimulate the parts of the human brain influenced by dopamine A chemical messenger (neurotransmitter) that regulates movement and emotions.. In effect, the brain is tricked into thinking it is receiving the dopamine it needs. In general, dopamine agonist A class of medications used to treat Parkinson's disease. Agonists enhance the activity of a neurotransmitter – in this case, dopamine. Ropinirole (Requip), pramipexole (Mirapex), rotigotine (Neupro) and apomorphine (Apokyn) are common dopamine agonists. are not as potent as carbidopa A medication used together with levodopa to enhance its effects. When carbidopa is added to levodopa, the dose of levodopa you take can be smaller while still getting the same benefits, with fewer side effects./levodopaThe medication most commonly given to control the movement symptoms of Parkinson’s, usually with carbidopa. It is converted in the brain into dopamine. and may be less likely to cause dyskinesiasAbnormal, involuntary body movements that can appear as jerking, fidgeting, twisting and turning movements; frequently caused by dopaminergic medications to treat Parkinson’s..

Dopamine agonists can be taken alone or in combination with medications containing levodopa. The two most commonly prescribed oral pill agonists in the U.S. are pramipexole (Mirapex) and ropinirole (Requip). A third, rotigotine transdermal system (Neupro®), was re-approved after several years of being off the market. Bromocriptine (Parlodel®) is available, but is less common.

One dopamine agonist, apomorphine (Apokyn), is a powerful and fast-acting injectable medication that promptly relieves symptoms of PD within minutes, but only provides 30 to 60 minutes of benefit. With training provided by the PD specialist, people with PD, spouses and family members can be taught to administer the agent, using a pre-filled syringe system. Its main advantage is its rapid effect. It is used for people who experience sudden wearing-off spells when their PD medication abruptly stops working, leaving them unexpectedly immobile. Apomorphine may cause severe nausea, and so people using this agent must take an antiemetic agent. In addition, apomorphine can provoke dyskinesias and other side effects associated with dopamine drugs.

Consult a doctor before taking any of the following to avoid possible interactions: alcohol, anti-psychotics, medications that lower blood pressure, Navane® (thiothixene), Taractan® (chlorprothixene), Haldol® (haloperidol), Reglan® (metoclopramide), phenothiazines, thiozanthenes, cimetidine, phenothiazines, butyrophenones, Cipro® and benzodiazepines.

What Are the Facts?

  • Dopamine agonists are a different class of drugs than levodopa.
  • While levodopa is converted in the brain into dopamine, dopamine agonists actually mimic the effects of dopamine without having to be converted.
  • Apart from carbidopa/levodopa, dopamine agonists are often the first medication prescribed to treat PD, but can also be used in later stages of PD with carbidopa/levodopa.

What are the side effects?

  • Excessive daytime sleepiness A chronic condition characterized by difficulty staying awake or paying attention; may be due to underlying sleep disorders, depression or some medications. or sudden sleep attacks
  • Visual hallucinationsSomething you see, hear, smell, taste or feel that is not actually there.
  • Confusion
  • Swelling of the ankles
  • Dyskinesia (not as common)
  • Compulsive behaviors (such as uncontrolled shopping, gambling, eating, and sexual urges)

Note: Pergolide and Bromocriptine are no longer available in the U.S. as treatment for Parkinson's.

Caution: PD medications may have interactions with certain foods, other medications, vitamins, herbal supplements, over the counter cold pills and other remedies. Anyone taking a PD medication should talk to their doctor and pharmacist about potential drug interactions.

APOKYN™ Injection (Apomorphine Hydrochloride)

Available Doses: .02 mL – .06 mL

Initial Dosing: .02 mL during “off” periods

Side Effects*: Nausea, vomiting, low blood pressure, sleepiness, dyskinesias, hallucinations, chest pain

Indications: Adjunct levodopa therapy to treat “off” periods

Interactions: 5HT3 agonists (for example, Zofran®, Kytril®) antihypertensives (for example Norvasc® and Zestril®)

Bromocriptine (Parlodel®)

Available Doses: 2.5 mg – 5 mg

Initial Dosing: 2.5 mg 3X/day

Side Effects*: Low blood pressure, nausea, edema, confusion, dry mouth, depression A mood disorder whose symptoms can include a persistent sad or empty mood, feelings of hopelessness or pessimism, irritability and loss of interest or pleasure in previously enjoyable activities., headaches

Indications: First course of treatment alone or with levodopa; mimics dopamine to manage major symptoms

Interactions: Alcohol, anti-psychotics, blood pressure lowering medications

Rotigotine Transdermal System (Neupro®)

Available Doses: 2mg/24hrs; 4 mg/24hrs; 6 mg/24hrs; 8 mg/24hrs

Initial Dosing: One 2 mg patch a day

Side Effects*: Nausea, application site reactions, somnolence, dizziness, headache, vomiting, sleep attacks, insomnia, impulse control disorder.

Indications: First course of treatment alone or with levodopa in early-stage idiopathicDescribes a disease or condition for which the cause is unknown. PD; for advanced stage idiopathic PD; mimics dopamine to manage major symptoms.

Interactions: May cause allergic-type reactions including anaphylactic symptoms especially in people sensitive to sulfites, including those with asthma.

Pramipexole (Mirapex®)

Available Doses: .125 mg; .25 mg; .5 mg; 1 mg; 1.5 mg

Initial Dosing: Taken two to six times a day for a maximum of 4.5 mg

Side Effects*: Arthritis, chest pain, nausea, low blood pressure, sleep disturbances, sedation, impulse control disorder

Indications: First course of treatment alone or with levodopa; mimics dopamine to manage major symptoms

Interactions: Sedatives and tranquilizers; metocipramide, thiozanthenes, cimetidine, phenothiazines, butyrophenones

Pramipexole Dihydrochloride Extended-Release (Mirapex ER®)

Available Doses: .375 mg; .75 mg.; 1.5 mg; 3 mg; 4.5 mg

Initial Dosing: Taken two to six times a day for a maximum dose of 4.5 mg; Dose may be increased gradually, not more frequently than every five to seven days, first to 0.75 mg per day and then by 0.75 mg increments up to a maximum recommended dose of 4.5 mg per day.

Side Effects*: Somnolence (sleepiness), nausea, constipation, dizziness, fatigue, hallucinations, dry mouth, muscle spasms, peripheral edema, impulse control disorder

Indications: For the treatment of the signs and symptoms of early PD

Interactions: Dopamine antagonists 

Ropinirole (Requip®)

Available Doses: .25 mg; .5 mg; 1 mg; 2 mg; 3 mg; 4 mg; 5mg

Initial Dosing: Taken two to six times a day for a maximum dose of 24 mg

Side Effects*: Abdominal pain, sleep disturbances, nausea, low blood pressure, sedation, impulse control disorder

Indications: First course of treatment alone or with levodopa; mimics dopamine to manage major symptoms

Interactions: Alcohol, anti-depressants, Cipro®, anti-psychotics, benzodiazipines

Ropinirole Extended-Release Tablets (Requip® XL™)

Available Doses: (All doses taken once a day); 2 mg; 4 mg; 6 mg; 8 mg; 10 mg; 12 mg; 14 mg; 16 mg; 18 mg; 20 mg; 22 mg; 24 mg

Initial Dosing: Taken two to six times a day for a maximum dose of 24 mg

Side Effects*: Nausea, dizziness, drowsiness, or sleepiness, headache, sudden uncontrolled movements (dyskinesia), abdominal pain/discomfort, hallucination, constipation and increase or decrease in blood pressure and heart rate. Patients should also tell their doctor if they experience new or increased gambling, sexual, or other intense urges while taking Requip XL. Requip XL may increase the side effects of levodopa.

Indications: First course of treatment alone or with levodopa; mimics dopamine to manage major symptoms. 24-hours continuous delivery of the medicine to provide smooth blood levels

Interactions: Inhibitors (e.g., ciprofloxacin, fluvoxamine) or inducers (e.g., omeprazole or smoking) of CYP1A2 higher doses of estrogen, usually associated with hormone replacement therapy (HRT), dopamine antagonists, such as neuroleptics Drugs that block dopamine receptors, usually prescribed to treat psychiatric symptoms. Because they block dopamine they cause Parkinson’s symptoms to worsen and should not be prescribed for someone with PD. (e.g., phenothiazines, butyrophenones, thioxanthenes) or metoclopramide.

* Please note that the side effects listed in the tables that accompany each class of medication are the most commonly experienced. Not all individuals will experience such side effects. For many people who experience side effects, they can often be effectively limited or eliminated with careful adjustments to dosage.

Speak to the treating physician immediately if any side effects are experienced. For a complete description of each drug and its possible side effects, please request a “package insert” from your pharmacist for each drug used. It is recommended that all prescriptions be filled at the same pharmacy to avoid interactions between medications. Interactions can be dangerous and even life-threatening, so make sure the pharmacist knows of all medications and supplements being taken, including over-the-counter medications and supplements.

Page reviewed by Dr. Chauncey Spears, Movement Disorders Fellow at the University of Florida, a Parkinson’s Foundation Center of Excellence.

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