FDA approves gabapentin enacarbil for RLS

April 15, 2011

FDA has approved gabapentin enacarbil (Horizant Extended-Release Tablets, GlaxoSmithKline and XenoPort), a once-daily treatment for moderate-to-severe restless legs syndrome, also known as Ekbom disease. It is the first medication in its class to be approved for this condition.

FDA has approved gabapentin enacarbil (Horizant Extended-Release Tablets, GlaxoSmithKline and XenoPort), a once-daily treatment for moderate-to-severe restless legs syndrome (RLS), also known as Ekbom disease. It is the first medication in its class to be approved for this condition.

RLS is a neurologic disorder that causes a strong urge to move the legs due to unpleasant feelings in the legs. People who have RLS describe feelings of pulling, itching, tingling, burning, or aching in their legs, and moving the legs temporarily relieves these feelings. The urge to move often happens when a person is inactive, and the symptoms typically are worse in the evening and early morning.

According to the RLS Foundation, up to 10% of the US population may have RLS. Many people have a mild form of the disorder, but RLS severely affects the lives of millions of individuals.

“FDA approval of a new medication for RLS is wonderful news for the community of affected individuals,” Georgianna Bell, executive director of the RLS Foundation, told Formulary. “RLS/Ekbom disease may significantly disrupt people’s lives - both physically and emotionally.”

Since symptoms occur or worsen in the evening and are relieved with movement, RLS/Ekbom disease may severely interfere with one’s sleep through the night. In turn, sleep deprivation causes stress and affects relationships, work, and families. The symptoms of RLS/Ekbom disease may also interfere with daily activities such as travel over distances by plane or automobile, concert attendance, concentration upon work or school tasks, and the ability to sit through a business meeting.

“It is our hope that people suffering from RLS/Ekbom disease will benefit from increased awareness of the disease among healthcare providers and from the ability to choose from proven treatments,” Bell added. “We encourage scientists to further identify and develop effective treatments. In addition, the RLS Foundation will continue its work to research the cause of this condition and to identify a cure.”

The effectiveness of Horizant was studied in 2 12-week clinical trials in adults. The trials showed that people taking the medication had an improvement in their RLS symptoms, compared to people taking placebo.

Horizant will be dispensed with an FDA-approved Medication Guide that explains the drug's uses and risks. Horizant may cause drowsiness and dizziness and can impair a person’s ability to drive or operate complex machinery. It is not recommended for patients who are required to sleep during the daytime and remain awake at night.

The recommended dosage of Horizant is 600 mg once daily, taken with food at about 5 p.m. A daily dose of 1,200 mg provided no additional benefit compared with the 600-mg dose, but caused an increase in adverse reactions.

Gabapentin enacarbil is a prodrug of gabapentin, an antiepileptic drug (AED). AEDs carry warnings that they may cause suicidal thoughts and actions in a small number of people. Horizant will have the same warning.

According to Randy Vogenberg, PhD, principal at the Institute for Integrated Healthcare in Sharon, Mass., and executive director of the Biologic Access & Finance program at The Jefferson School of Population Health in Philadelphia, this is an interesting area for medical treatment as well as dealing with benefit coverage.

“One perspective is the medical need that can be effectively addressed and the other is whether this disease category needs to be under coverage or considered more of a lifestyle issue,” said Vogenberg, who is also author of Pharmacy Benefits: Plan Design and Management. “As more information comes out on this drug’s study, it can help answer questions that have been lingering in the market place for awhile among HR and benefit managers.”