Patients with Restless Legs Syndrome Find Relief with Gabapentin Enacarbil


gabapentin enacarbilGabapentin Enacarbil, CAS number 478296-72-9, is also known as Horizant, which is marketed by GlaxoSmithKline. As a medication approved by the FDA to treat Moderate-to-Severe Primary Restless Legs Syndrome {RLS}, this drug is a welcome relief for patients who suffer from this frustrating neurological condition. RLS is more likely to occur in women, and includes symptoms such as an urge to move the legs, alongside uncomfortable and unpleasant pain sensations in the legs. Symptoms of RLS tend to occur during periods of rest or inactivity, such as nighttime. There is currently no cure for this chronic condition, and the advent of gabapentin enacarbil has offered new hope for patients with RLS.

Approved by the FDA on April 6, 2011, gabapentin enacarbil is the first medication in its class to be approved for the treatment of moderate-to-severe primary Restless Legs Syndrome. The once daily dosing at 5 pm has proven in a variety of clinical trials to be effective and tolerable. One particular trial, sponsored in part by the manufacturer of Horizant, XenoPort Inc., evaluated 220 patients with moderate-to-severe RLS for 12 weeks. The patients were randomized to receive either a placebo or 1200 milligrams of gabapentin enacarbil once daily. Patients used the International Restless Legs Syndrome Severity Scale to rate their relief from gabapentin enacarbil, and indicated considerable improvement in their symptoms after receiving this medication. Side effects are typically mild, with patients finding dizziness and drowsiness to be typical problems.

Patients with pain from RLS reported significant improvement in their pain and discomfort after 3 months of treatment with gabapentin enacarbil. Daniel O. Lee, MD, of East Carolina Neurology, Greenville, N.C., and colleagues conducted a post hoc analysis of data from a phase III trial of gabapentin enacarbil. This trial, which included 279 patients, offered trial participants either 12 weeks of 600 milligrams of gabapentin enacarbil, 1,200 milligrams of gabapentin enacarbil or a placebo. The baseline measured in this randomized trial documented 91% of patients reported experiencing pain. A staggering 57% of these patients also noted their average daily pain scores of four or higher, out of 10. Of the participants who received 1,200 milligrams of gabapentin enacarbil, 69.1% reported a 30% reduction in average daily pain scores, compared with 51.6% of patients who had received a placebo. Patients who were dosed with 600 milligrams of gabapentin enacarbil had similar results, with 67.6% reporting a 30% reduction in pain associated with their RLS symptoms. Currently gabapentin enacarbil is available in tablet form, in doses of 300 and 600 milligrams each, under the brand name Horizant.

Restless Legs Syndrome
Sleep pattern of a restless legs syndrome patient (red) vs. a healthy sleep pattern (blue).

Restless legs syndrome may also known as Willis-Ekbom disease (WED), and is a disruptive neurologic disorder that adversely affects 2-3% of the U.S. population. With many patients experiencing mild symptoms of RLS there is a potential uptick in cases as more patients become aware that RLS may be the cause of their nighttime discomfort. Experts at the RLS Foundation believe that up to 10% of the U.S. adult population may have Restless Leg Syndrome, but are currently undiagnosed. Research and development teams are working tirelessly on generic formulations of gabapentin enacarbil for the expected increase in RLS diagnoses and need for safe and efficacious treatments to combat this debilitating condition. LGM Pharma is a provider of the API gabapentin enacarbil, and offers continual support for clients throughout the R&D process.

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