Simulated Driving Study in Restless Legs Syndrome
Condition: Restless Legs Syndrome
MeSH terms: Psychomotor Agitation; Restless Legs Syndrome; Syndrome
Intervention: XP13512; Diphenhydramine; Placebo
Intervention description: XP13512 once daily for 16 days; one 50 mg dose of diphenhydramine (DPH) on day 16; XP13512 placebo once daily for 16 days
Intervention MeSH terms: Diphenhydramine; Promethazine; Gabapentin
Phase: Phase 2
Study type: Interventional
Primary purpose: Treatment
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Participant, Investigator)
Enrollment: 130.0
Sex: All
Minimum age: 21 Years
Maximum age: 65 Years
Healthy volunteers: No

Summary:

      This study was a multi center, randomized, double blind, active and placebo controlled,
      parallel group study to assess simulated driving performance in XP13512 treated subjects with
      Restless Legs Syndrome (RLS). Eligible subjects were randomized to receive a once daily dose
      of placebo (2 groups), XP13512 1200 mg, or XP13512 1800 mg for 16 days. On Day 16, one of the
      placebo groups also received one 50 mg dose of diphenhydramine (DPH) to assess the effects of
      an agent known to have sedative properties, while the other 3 groups received a DPH placebo.
    

Eligibility criteria:

        Inclusion Criteria:

          -  Men or women who were 21 through 65 years of age and fluent in English;

          -  Subjects with RLS, based on the IRLSSG Diagnostic Criteria;

          -  Currently a licensed and experienced driver who has driven an average of 3 or more
             times/week for the past 3 years;

          -  Able to successfully complete the 5 minute practice simulated driving test at
             Screening;

          -  History of RLS symptoms at least 15 nights in the prior month or, if on treatment,
             this frequency of symptoms before treatment was started;

          -  Total RLS severity score of 15 or greater on the IRLS Rating Scale;

          -  Documented RLS symptoms for at least 4 of the 7 consecutive evenings/nights
             Discontinuation of treatments for RLS (e.g., opioids, benzodiazepines, dopamine
             agonists and/or gabapentin) at least 2 weeks prior to Screening; -

          -  Body Mass Index of 34 or below;

          -  Estimated creatinine clearance of at least 60 mL/min;

          -  Agreed to maintain abstinence from alcohol and smoking throughout the entire study
             period;

          -  Agreed to maintain abstinence from caffeine from midnight of the day prior to and
             until the end of each Visit (Visits 2 to 4).

        Exclusion Criteria:

          -  A sleep disorder (e.g., sleep apnea) other than RLS that may significantly affect the
             assessment of RLS;

          -  Current use of a sleeping medication or sedating medication;

          -  Current use of CNS stimulants;

          -  Neurologic disease or movement disorder;

          -  Other medical conditions which could affect RLS assessments;

          -  Significant medical history that may impair psychomotor coordination;

          -  Subjects who had clinically significant or unstable medical conditions;

          -  Serum ferritin level below 20 ng/mL;

          -  Subjects currently suffering from moderate or severe depression using the Diagnostic
             and Statistical Manual of Mental Disorders and Treatment IV (DSM IV TR);

          -  Subjects with a history of substance abuse (alcohol or drugs) or substance dependence
             within 12 months prior to enrollment;

          -  Shift workers or subjects who were not on normal day/night sleep cycles;

          -  Subjects who had smoked an average of greater than one half pack of cigarettes (or
             nicotine equivalent) per day within 30 days of the Screening Visit;

          -  Subjects who had consumed an average of >5 cups (i.e., 40 ounces) of caffeinated
             beverages per day within 20 days of the Screening Visit;

          -  Subjects with a history of allergy to gabapentin, diphenhydramine, or XP13512
             excipients