Restless Legs Syndrome and Related Disorders - Medications

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Dopaminergic drugs include dopamine precursors and dopamine receptor agonists.

Dopamine Precursors. The dopamine precursor levodopa (L-dopa) was once a popular drug for severe RLS. Although it can still be useful, most doctors now prefer the newer dopamine agonists (see below). The standard preparations (Sinemet, Atamet) combine levodopa with carbidopa, which improves the action of levodopa and reduces some of its side effects, particularly nausea. Levodopa can also be combined with benserazide (Madopar) with similar results, but Sinemet is almost always used in America. (Levodopa combinations are well tolerated and safe.)

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Patients typically start with a very low dose taken 1 hour before bedtime. The dosage is increased until the patient finds relief. Patients sometimes need to take an extended-release form or to take it again during the night.

Levodopa acts fast, and the treatment is usually effective within the first few days of therapy.

Serious common side effects of L-dopa treatment (and, to lesser extent, of dopamine receptor agonists) are augmentation and rebound. Many studies report that augmentation (worsening of symptoms that occur earlier in the day) occurs in up to 70% of patients who take L-dopa. The risk is highest for patients who take daily doses, especially doses at high levels (greater than 200 mg/day). For this reason, patients should use L-dopa only intermittently (fewer than 3 times per week). The drug should be immediately discontinued if augmentation does occur. Following withdrawal from L-dopa, patients can switch to a dopamine receptor agonist.

The rebound effect causes increased leg movements at night or in the morning as the dose wears off, or as tolerance to the drug builds up.

Dopamine Receptor Agonists. Dopamine receptor agonists (also called dopamine agonists) mimic the effects of dopamine by acting on dopamine receptors in the brain. They are now generally preferred to L-dopa. Because they have fewer side effects than L-dopa, including rebound effect and augmentation, these drugs may be used on a daily basis. About 30% of patients who take dopamine receptor agonists have reported augmentations symptoms. As the newer drugs are taken for longer periods and at higher doses, however, their augmentation rates may become closer to those of L-dopa.