Augmentation and tolerance with long-term pramipexole treatment of restless legs syndrome (RLS)

Dopaminergic agents have become first-line treatments for restless legs syndrome (RLS). The most common serious complications of L-Dopa treatment of RLS are "augmentation", in which RLS symptoms appear earlier during the day, and tolerance, in which medication effectiveness wanes over time. The aims of this study were to assess rates of augmentation and tolerance, and their interrelationship, with pramipexole treatment of RLS.

Retrospective assessment of all patients (N=59) treated for RLS with pramipexole for at least 6 months (mean duration=21.2+/-11.4 months) by the senior author. Pramipexole dosing and clinical follow-up were performed in a standardized fashion. L-Dopa was discontinued and other medications for RLS were tapered as tolerated. Rates of augmentation (need for earlier administration of the same dose of pramipexole) and tolerance (need for an increase in pramipexole dose) were determined.

Augmentation developed in 32% (19/59), and tolerance occurred in 46% (27/59), of patients. These two complications were statistically related (P<0.05). The only clinical predictors of these complications were previous augmentation or tolerance to L-Dopa.

Augmentation and tolerance are more common with extended pramipexole treatment of RLS than has been previously reported in preliminary studies. However, these complications are generally manageable by earlier dosing or small dose increases of this agent, and only rarely require medication discontinuation.