The Effect of Horizant (Gabapentin Enacarbil) on Augmentation

Not Applicable

Completed

Brief Summary: Restless Legs Syndrome (RLS) is a common neurological disorder. Augmentation is the main complication during long-term DA treatment of RLS. This study aims to examine effect of Horizant (Gabapentin Enacarbil) on Augmentation in RLS patients.

Detailed Description: This is an Open label single arm study. The purpose of the study is to demonstrate the efficacy of Horizant in patients with RLS who exhibit augmentation while on Dopaminergic therapy. Adult patients (age 18-85 years) with diagnosis of primary RLS (diagnosed by study investigators) with augmentation on dopaminergic therapy will be screened for participation in the study. RLS diagnosis will be made by the study investigators using International RLS study group criteria. Patients with augmentation on dopaminergic therapy as defined by NIH 2007 with ASRS of 5 to 15 will be offered to participate in the study. Inclusion and exclusion criteria are listed below. The study will be performed after approval of the Institutional Review Board of the University of Missouri.

A total of 50 subjects will be entered into the study over a period of 1 year. Written consent will be obtained from all patients. After pre-participation evaluation for eligibility, subjects will be selected and enrolled in the study and followed for a total of 6 follow up visits (Days 0, 30, 90, 120, 180, 360). Subjects Enrollment period will last up to 12 months. The total duration of study will be 24 months.

Recruitment & Eligibility

Inclusion Criteria

Adult patients with diagnosis of RLS for more than one year.
Patients who are on DA therapy for 6 months or longer.
Patients who developed Augmentation (on stable dose of DA) lasting for 3 months or longer.
Augmentation severity rating scale of 5 to 15.
Both males and females
Age range = 18-85 year

Exclusion Criteria

Known Hypersensitivity to Horizant or Gabapentin products
Peripheral neuropathy
Radiculopathy
Peripheral vascular disease
Uremia [abnormal blood urea nitrogen (BUN) or Creatinine on Comprehensive Metabolic Panel (CMP)]
Anemia
Patients who are currently pregnant
Patients who currently take opioids, lithium, anti-nausea medications (e.g. metoclopramide), dopaminergic antagonists (e.g. Haloperidol), 1st generation antihistamines (e.g. diphenhydramine, pseudoephedrine), anti-psychotic medications and iron therapy.
Subjects with impaired decision making capability.

Arm && Interventions

Group	Intervention	Description
open-label	Horizant	open-label single arm study Horizant, 600 mg oral once daily at 5 pm for 360 days.

Primary Outcome Measures

Name	Time	Method
Change in Augmentation Severity From Day 0 to Day 90	From Day 0 (Baseline) to Day 90	Augmentation severity rating scale; 0-24, 0 is better, 24 is worst

Secondary Outcome Measures

Name	Time	Method
Change in Augmentation Severity Rating Scale Form Day 0 to Day 360 (270 Days After Discontinuation pf Dopaminergic Medication)	Day 0 to day 360 (270 days after discontinuing dopaminergic medication)	Numeric Scale to assess degree of augmentation; Range 0-24; 0 is better, 24 is worst. We compared the Augmentation severity scale on day 0 to day 360 (which is 270 days after this decrease of dopaminergic medication)