(Brand names in India: Pramipex, Pramipex ER, Ropark, Ropark XL)
How do dopamine agonists work?
These chemicals are imitators.
They look just like Dopamine itself. They attach themselves to the same sites that Dopamine usually attaches itself. Therefore, they produce similar effects in the brain as Dopamine and relieve the symptoms of Parkinson’s disease.
- “Extended-release” / 24-hour preparations: The main advantage is that these medications have “extended-release preparations” that gradually dissolve in the stomach so that they keep gradually entering the blood and then the brain for the entire day. Therefore the effects of a single tablet taken in the morning can last for 24 hours. This infrequent dosing is very convenient! But even more importantly in patients who have Predictable-wearing-OFF or other motor fluctuations with levodopa, these long-acting medications can maintain good movement throughout the day, to “smoothen out the day”.
- They may produce less dyskinesias than levodopa. They may therefore be used to start treatment in younger patients (e.g. below 45) or may be added to the treatment of a person who cannot tolerate high doses of levodopa due to dyskinesias.
- These medications are not as strong as levodopa. When given in smaller doses, they may not relieve all the symptoms of Parkinson’s disease.
- When given in higher doses, they can produce troublesome side-effects including excessive daytime sleepiness, impulse control problems such as gambling and rarely, sleep disturbances & hallucinations. In particular, the excessive sleepiness during the day often limits their use – restricting their use to smaller doses.
While good in theory, it is difficult to use these medications in practice. They are sometimes used for the treatment of very young patients with Parkinson’s disease. Also, the fact that 24 hour preparations are available make these medications useful in certain niche situations such as predictable-wearing OFF.
Dr. Kharkar is a Neurologist, Epilepsy specialist & Parkinson’s disease specialist in Mumbai, Maharashtra, India.
He has trained in the best institutions in India, US and UK including KEM hospital in Mumbai, Johns Hopkins University in Baltimore, University of California at San Francisco (UCSF), USA & Kings College in London.
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