A Long-Term Extension Trial From Late Phase II of SPM 962 in Patients With Restless Legs Syndrome

Inclusion Criteria: * Subject completed the preceding trial 243-07-003 (NCT00666965) Exclusion Criteria: * Subject discontinued from the preceding trial 243-07-003 (NCT00666965) * Subject had a serious adverse event which association with the investigational drug is not ruled out during trial 243-07-003 * Subject had a persistent serious adverse event at the baseline, which was observed and association with the investigational drug is ruled out during trial 243-07-003. * Subject had persistent hallucination or delusion during trial 243-07-003. * Subject had psychiatric conditions such as confusion, excitation, delirium, abnormal behaviour at the baseline. * Subject had orthostatic hypotension or a systolic blood pressure (SBP) ≤ 100 mmHg and had a decrease of SBP from spine to standing position ≥ 30 mmHg at baseline. * Subject had a history of epilepsy, convulsion etc. during trial 243-07-003. * Subject developed serious ECG abnormality at the baseline. * Subject had QTc-interval ≥ 500 msec at the baseline or subject had an increase of QTc-interval ≥ 60 msec from the baseline in the trial 243-07-003 and had a QTc-interval \> 470 msec in female or \> 450 msec in male at the baseline. * Subject had a serum potassium level \< 3.5 mEq/L at the end of the taper period in trial 243-07-003. * Subject had a total bilirubin ≥ 3.0 mg/dL or AST(GOT) or ALT(GPT) greater than 2.5 times of the upper limit of the reference range (or ≥ 100 IU/L) at the end of the period in trial 243-07-003. * Subject had BUN ≥ 30 mg/dL or serum creatinine ≥ 2.0 mg/dl at the end of the taper period in trial 243-07-003. * Subject who planned pregnancy during the trial. * Subject was judged to be inappropriate for this trial by the investigator for the reasons other than above.