SEATTLE, WA—Treatment with gabapentin enacarbil at both the 600mg and 1200mg doses “led to a greater number of adult patients who met the criteria for a combined pain and International Restless Legs Scale (IRLS) total score response” compared to placebo, a study presented at SLEEP 2015 confirmed.

A team of researchers led by Aaron Ellenbogen, DO, from the Michigan Institute for Neurological Disorders, Farmington Hills, MI, conducted a pooled analysis to explore whether adults with moderate-to-severe primary RLS experienced improved pain and RLS symptoms after treatment with gabapentin enacarbil. They assessed the relationship with treatment and the Pain and International Restless Legs Scale (IRLS) total score.

Data from three randomized, 12-week, double-blind trials comparing gabapentin enacarbil 600mg, 1200mg, and placebo were compiled. Pain responders included in the analysis had a baseline IRLS total score ≥15 and pain score ≥4. Patients had a ≥30% pain score improvement on a numeric rating scale, typically considered a notable improvement. Of the total 671 patients identified, 366 met the inclusion criteria, 133 from the placebo arm, 86 from the gabapentin enacarbil 600mg arm, and 147 from the gabapentin enacarbil 1200mg arm.

At 12 weeks, response for pain and IRLS total score was observed in 40% of the placebo group, 70% of the gabapentin enacarbil 600mg group, and 67% of the gabapentin enacarbil 1200mg group. Non-responders in either category were seen in 35%, 16%, and 18% of the groups, respectively. Dr. Ellenbogen noted that few patients were responders only for pain: 16% of the placebo group, 9% of the gabapentin enacarbil 600mg group, and 12% of the gabapentin enacarbil 1200mg group, or IRLS total score alone,  9%, 5%, and 4% of the groups, respectively.

The differences across all categories were significant between gabapentin enacarbil 600mg vs. placebo (P=0.0003) as well as gabapentin enacarbil 1200mg vs. placebo (P<0.0001).

“These data further highlight the integral role of pain in RLS as seen by the shift in the concomitant response to both pain and IRLS in the majority of patients, compared with response to either pain or IRLS alone,” Dr. Ellenbogen stated. “This analysis also confirms that pain scores correlate with RLS symptoms.”

The most common treatment-emergent adverse effects were somnolence and dizziness.