Pain is a commonly associated symptom of restless legs syndrome (RLS), and data presented at SLEEP 2015 and published in the Sleep online supplement suggest Horizant (gabapentin enacarbil) has a positive effect on both pain outcomes and RLS symptoms.

In a pooled analyses from three randomized controlled trials, the researchers found that most patients were joint responders for pain and IRLS total score, and more gabapentin enacarbil (GEn)-treated patients (600 mg and 1,200 mg) had a joint response versus placebo. There were significant correlations between the change from baseline in pain and International Restless Legs Scale (IRLS) total score.

Three hundred sixty-six of 671 patients met analysis entry criteria (placebo, n=133; GEn 600 mg, n=86; GEn 1200 mg, n=147). Most patients were joint responders for pain and IRLS total score (placebo, 40%; GEn 600 mg, 70%; GEn 1200 mg, 67%) and some were not responders in either category (35%; 16%; 18%, respectively). Few patients were responders only for pain (placebo, 16%; GEn 600 mg, 9%; GEn 1200 mg, 12%) or IRLS total score (9%; 5%; 4%, respectively). Differences across all 4 categories were significant between GEn 600 mg vs placebo (Chi Square, P=.0003) and GEn 1200 mg vs placebo (Chi Square, P<.0001). Moderate to strong correlations were observed between IRLS total score and pain score for change from baseline to week 12 (placebo, 0.69; GEn 600 mg, 0.54; GEn 1200 mg, 0.68; all P<.0001). The most common treatment-emergent adverse events in the individual studies were somnolence and dizziness.

These studies and this analysis were conducted by XenoPort Inc, makers of Horizant. Medical writing support was provided by CodonMedical, a division of KnowledgePoint360, and was funded by XenoPort. The abstract is titled “The Effect of Gabapentin Enacarbil (GEn) on Pain Outcomes and Restless Legs Syndrome (RLS) Symptoms in Adults with Moderate-to-Severe Primary RLS: Pooled Analyses from 3 Randomized Controlled Trials.”

Other data presented at the SLEEP meeting and in the supplement suggest RLS symptoms and pain may be clinically related, as most patients had a joint response for pain and RLS symptoms. The abstract is titled “Association Between Pain and Symptoms of Restless Legs Syndrome (RLS) in Adults with Moderate-to Severe Primary RLS in a Combined Treatment Population: Pooled Analyses from 3 Randomized Controlled Trials.”