Data Presented at the American Academy of Neurology Show XP13512/GSK1838262 Significantly Improved Symptoms of Moderate-to-Severe Primary Restless Leg...(ommercially-available gabapentin. Abs...),Health

Absorption of commercially-available gabapentin is limited to a narrow region in the intestinal tract and can saturate at normal clinical doses. Once saturation occurs, additional gabapentin can not be absorbed. In addition, absorption rates can vary from patient to patient. In contrast, studies with both the immediate-release and the sustained-release formulations indicated that XP13512 was well-absorbed, converted rapidly to gabapentin and provided high bioavailability (>70 percent) and dose-proportional exposure.

"XP13512 is absorbed by high-capacity nutrient transporters located throughout the intestinal tract," said Ken Cundy, Ph.D., senior vice president, Preclinical Development for XenoPort. "The unique absorption mechanism of this compound overcomes the pharmacokinetic limitations of commercially-available gabapentin and allows for sustained, dose-proportional exposure to gabapentin."

About PIVOT RLS I (Study XP052)

PIVOT RLS I, a 12-week, multicenter, randomized, double-blind, placebo- controlled clinical trial of XP13512 was designed to assess efficacy and tolerability in adults with moderate-to-severe primary RLS. The study included 220 patients randomized to receive either XP13512 1200 mg (n=112) or placebo (n=108) once-daily at 5:00 p.m. with food. Co-primary endpoints in the study were mean change from baseline in the International Restless Legs Syndrome (IRLS) Scale total score and the proportion of responders (defined as ratings of 'very much improved' or 'much improved') on the investigator-rated Clinical Global Impression of Improvement (CGI-I) Scale at Week 12. Adverse events, vital signs and laboratory tests were used to assess tolerability.

Study results showed that the unadjusted mean change from baseline in IRLS Scale total score at Week 12 was significantly greater for XP13512 (-13.2) compared to placebo (-8.8) with an adjusted mean treatment difference of -4.0, 95% CI: (-6.
'/>"/>