Which medications in the drug class Dopamine Agonists are used in the treatment of Parkinson Disease?

Updated: Jan 24, 2019
  • Author: Robert A Hauser, MD, MBA; Chief Editor: Selim R Benbadis, MD  more...
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Answer

Dopamine Agonists

Dopamine agonists are effective as monotherapy in early PD and as adjuncts to levodopa/PDI (peripheral decarboxylase inhibitor) in moderate to advanced disease. Dopamine agonists directly stimulate postsynaptic dopamine receptors to provide antiparkinsonian benefit. All available dopamine agonists stimulate D2 receptors, an action that is thought to be clinically beneficial. The role of other dopamine receptors is currently unclear.

Dopamine agonists are effective to treat motor features of early PD, and they cause less development of motor fluctuations and dyskinesia than levodopa. For patients with motor fluctuations on levodopa/PDI, the addition of a dopamine agonist reduces off time, improves motor function, and allows lower levodopa doses.

Carbidopa/levodopa (Sinemet, Sinemet CR, Rytary, Duopa)

Carbidopa/levodopa is approved for the treatment of symptoms of idiopathic PD, postencephalitic parkinsonism, and symptomatic parkinsonism that may follow injury to the nervous system by carbon monoxide and/or manganese intoxication. Levodopa, combined with a peripheral decarboxylase inhibitor (PDI) such as carbidopa, is the criterion standard of symptomatic treatment for PD; it provides the greatest antiparkinsonian efficacy in moderate to advanced disease with the fewest acute adverse effects. When administered alone, levodopa causes a high incidence of nausea and vomiting due to the formation of dopamine in the peripheral circulation. Carbidopa inhibits the decarboxylation of levodopa to dopamine in the peripheral circulation thereby reducing nausea and allowing for greater levodopa distribution into the CNS. Carbidopa does not cross the blood-brain barrier.

Sustained-release capsules (Rytary) may improve drug delivery for patients unable to swallow effectively. The capsule may be either swallowed whole or opened and sprinkled on a small amount of applesauce for immediate consumption.

An enteral suspension (Duopa) is administered by a portable pump into the jejunum over a 16-hr period to improve on-time and decrease off-time in patients with motor fluctuations with advanced Parkinson disease.

Levodopa inhaled (Inbrija)

Powder for inhalation is systemically absorbed via lungs, and therefore bypasses GI absorption, which may be variable in patients with PD. Levodopa, the metabolic precursor of dopamine, crosses the blood-brain barrier and is converted to dopamine in the brain. It is indicated for intermittent treatment of "off" episodes in patients with Parkinson disease who are taking oral carbidopa/levodopa.

Apomorphine (Apokyn)

Apomorphine is a nonergoline dopamine agonist indicated for the acute, intermittent treatment of hypomobility "off" episodes ("end-of-dose wearing off" and unpredictable "on/off" episodes) associated with advanced PD. It is administered by a subcutaneous injection. Although the exact mechanism by which apomorphine exerts its therapeutic effects in PD is unknown, it is thought to occur via activation of postsynaptic D2 receptors in the striatum.

Pramipexole (Mirapex, Mirapex ER)

Pramipexole is approved as monotherapy in early disease and as adjunctive therapy to levodopa/PDI in more advanced stages. The mechanism of action of pramipexole as a treatment for PD is unknown, although it is believed to be related to its ability to stimulate D2 dopamine receptors in the striatum. It is available as an immediate-release and an extended-release tablet.

Ropinirole (Requip and Requip XL)

Ropinirole is approved as monotherapy in early disease and as adjunctive therapy to levodopa/PDI in more advanced disease. Ropinirole is a nonergot dopamine agonist that has high relative in vitro specificity and full intrinsic activity at the D2 subfamily of dopamine receptors; it binds with higher affinity to D3 than to D2 or D4 receptor subtypes. The mechanism of action of ropinirole is stimulation of dopamine D2 receptors in striatum. It is available as an immediate-release and an extended-release tablet.

Amantadine (Gocovri)

Amantadine is approved for the treatment of idiopathic PD, postencephalitic parkinsonism, and symptomatic parkinsonism, which may follow injury to the nervous system by carbon monoxide intoxication. The extended-release capsule is indicated for dyskinesia in patients with PD. Amantadine is available as a syrup, tablet, capsule, and an extended-release capsule. The exact mechanism of amantadine for the treatment of PD and dyskinesia associated with PD is unknown. Amantadine is a weak, noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist.

Rotigotine (Neupro)

Dopamine agonist stimulating D3, D2, and D1 receptors. Improvement in Parkinson-related symptoms thought to be its ability to stimulate D2 receptors within the caudate putamen in the brain. Indicated for the treatment of the signs and symptoms of idiopathic Parkinson disease (PD). Dosage ranges differ for early-stage PD and advanced-stage PD. Available as transdermal patch that provides continuous delivery for 24 h


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