To perform a pilot study assessing possible efficacy, safety, and optimal dosage of pramipexole in essential tremor.
Twenty-nine patients with essential tremor were enrolled into this 16-week-long study. After recording baseline condition, 2 different dosages of immediate-release formulation of pramipexole were evaluated (1.05 mg/d and 2.1 mg/d in 3 identical dosages). Subsequently, immediate- and extended-release formulations were compared. The Fahn-Tolosa-Marin Tremor Rating Scale, Activities of Daily Living, the EuroQol instrument for detecting health-related outcome, and Clinical Global Impression of Improvement Scale were obtained. After completing the study, a rater blinded to the treatment reassessed the tremor rating scales based on video recordings.
Twenty-four patients (82.6%) completed the study. Causes for discontinuation were adverse effects of pramipexole: intolerable nausea (n = 3), daytime sleepiness (n = 1), and anxiety (n = 1). Twenty-one patients had a score of less than 3 on the Clinical Global Impression of Improvement Scale (treatment responders, 72.4%). All the major outcome values demonstrated significant improvement. The severity of tremor was reduced by 52.0% (43.7 vs 20.8 points, Fahn-Tolosa-Marin Tremor Rating Scale), and the EuroQol instrument for detecting health-related outcome score improved from 0.69 to 0.91 (P < 0.01). The dose of 2.1 mg was more effective than that of 1.05 mg; however, both the immediate- and extended-release formulations were equally efficacious. After completion of the study, 15 patients (51.7% of the enrolled patients) wanted to remain on pramipexole treatment.
This pilot study suggests that pramipexole may be effective in the treatment of essential tremor. However, further controlled studies are required.