Dopamine precursors and agonists for restless legs syndrome
Examples
Dopamine precursors
Generic Name levodopa Dopamine agonists
Generic Name bromocriptine mesylate (Parlodel) cabergoline (Dostinex) pramipexole (Mirapex) ropinirole hydrochloride (Requip) How It Works
Dopamine precursors are drugs that the brain converts to dopamine, a chemical (neurotransmitter) involved in controlling movement. Dopamine is involved in movement, sleep, emotions, alertness, and addictive behaviour.
Dopamine agonists directly stimulate nerves in the brain that are not naturally being stimulated by dopamine.
Why It Is Used
Dopamines are generally prescribed to treat Parkinson's disease. However, there seems to be a relationship between restless legs syndrome and abnormalities in how the body produces or uses dopamine. A doctor may prescribe medication as treatment for continuous symptoms that frequently disturb sleep, in which case dopamine agonists are usually the first choice.
How Well It Works
The dopamine agents that are effective and well studied in treating restless legs syndrome and involuntary or jerking leg movements (periodic limb movements) are levodopa, pramipexole, and ropinirole.1
Studies have shown that these drugs have helped some people control or improve their symptoms and have reduced the number of sleep disturbances.2 Although they may seem to help at first, in some people these medications seem to make symptoms worse later by a process called augmentation. Because this undesired outcome is most associated with regular use of levodopa, most patients who require daily medicine will need a dopamine agonist.
Side Effects
Side effects that may occur with levodopa, a dopamine precursor, include:
- Nausea and vomiting.
- Headache, dizziness, or fainting.
- Numbness, weakness, and grinding of teeth.
- Insomnia, agitation, anxiety, malaise, fatigue, and euphoria.
The most common side effects of dopamine agonists are:
- Nausea.
- Nasal congestion.
- Fatigue.
- Fluid retention.
- Unwanted sleepiness.
These side effects can sometimes be relieved by combining dopamine with other medications, such as domperidone or carbidopa. Certain rare side effects, called impulse control disorders (such as pathological gambling) have also occured in a few restless legs syndrome patients.
See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)
What To Think About
If you begin experiencing symptoms in the daytime as a result of these drugs, you may also be prescribed opioids or benzodiazepines.
More study is needed to discover the full range of side effects.
Problems related to the dosing of dopamine precursors and agonists can occur, such as:
- Rebound. This occurs when symptoms become worse at the end of a dosing period, usually late at night or in the morning.3
- Augmentation, which means that symptoms generally get worse. Symptoms begin to be noticed progressively earlier in the day, often in the afternoon or evening. Augmentation is most often a side effect of long-term dopamine use and usually becomes worse with increasing dosage. People with severe augmentation experience symptoms constantly. The discomfort may intensify and spread to the torso or the arms. Discontinuing the medication will usually return symptoms to the premedication level, even though at first they may temporarily get worse.3
To prevent rebound or augmentation, it may be helpful to split or lower the dosage or change the usual time the dose is taken.
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| Author: | Kathe Gallagher, MSW Cynthia Tank | Last Updated: May 24, 2007 |
| Medical Review: | Adam Husney, MD - Family Medicine Karin M. Lindholm, DO - Neurology Andrew Swan, MD, CCFP, FCFP - Family Medicine | |
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| Topic Contents | |
| Examples | |
| How It Works | |
| Why It Is Used | |
| How Well It Works | |
| Side Effects | |
| What To Think About | |
| References | |