FDA Approves Drug for Restless Legs Syndrome

(National Institute on Aging, NIH)

The U.S. Food and Drug Administration approved Horizant Extended Release Tablets, a once-daily treatment for moderate-to-severe restless legs syndrome (RLS). The drug was developed by Xenoport of Santa Clara, California and GlaxoSmithKline of Research Triangle Park, North Carolina.

Horizant’s compound is gabapentin enacarbil that uses the body’s nutrient transport mechanisms that are believed to help its absorption into the body. Once absorbed, Horizant is converted into gabapentin, which binds to a specific type of calcium channel but does not show an affinity for other common receptors.

Horizant’s effectiveness was studied in two 12-week clinical trials in adults. The trials showed that people taking the medication had an improvement in their RLS symptoms, compared with people taking a placebo.

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

Another caution concerns gabapentin, which Horizant becomes once absorbed into the body. Gabapentin is a drug used to treat seizures in people with epilepsy, and all drugs used to treat epilepsy carry warnings that they may cause suicidal thoughts and actions in a small number of people. Horizant will carry the same warning.

Restless legs syndrome is a neurological disorder characterized by unpleasant sensations in the legs and an uncontrollable, and sometimes overwhelming, urge to move them for relief. Individuals affected with the disorder often describe the sensations as throbbing, polling, or creeping. The sensations range in severity from uncomfortable to irritating to painful.

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