Restless legs syndrome is a common neurological disorder that frequently manifests itself as a sleep disorder. Patients who suffer from RLS experience an irresistible urge to move their legs. This urge is usually accompanied by unpleasant sensations of burning, creeping, tugging or tingling inside the patients’ legs, ranging in severity from uncomfortable to painful.
The placebo-controlled phase II clinical trial enrolled 95 patients diagnosed with RLS who received either placebo, 600mg of XP13512, or 1200mg of XP13512.
According to the test results, 81% of the patients who received 1200mg of XP13512 were “much improved” or “very much improved,” as compared to 48% of patients who received placebo. Treatment with 1200mg of XP13512 was associated with statistically significant improvements in a number of subjective measures of sleep, including overall quality of sleep, the number of awakenings per night due to RLS symptoms and the number of hours awake per night due to RLS symptoms.
Finally, treatment with 1200mg of XP13512, compared to placebo, was associated with a statistically significant reduction in the severity of RLS symptoms in the evening (8 p.m. to midnight) as measured using a 24-hr RLS symptom diary on the final day of treatment.
Clinical effects measured by the above endpoints in patients treated with 600 mg of XP13512 were not statistically different from patients treated with placebo.
Dr Ronald Barrett, chief executive officer for XenoPort, stated, “Importantly, XP13512 dosed once per day at a lower dose than our previous Phase 2a clinical trial led to similar significant improvements in RLS symptoms and sleep performance, as well as favorable patient and investigator reported overall outcomes. The information from this trial will be used to determine the dosing and patient requirements for our Phase III program for XP13512 in RLS patients, which we expect to initiate in the first half of 2006.”