WASHINGTON — The FDA has approved the restless legs syndrome drug gabapentin enacarbil (Horizant) to treat postherpetic neuralgia.
The drug is administered in one 600 mg dose for the first 3 days of treatment, followed by 600 mg doses twice daily on day four and onward, a statement from makers GlaxoSmithKline and XenoPort said.
Patients with renal impairment should have adjusted doses, the statement added.
Safety and efficacy for the new indication were evaluated in a 12-week principal efficacy trial and two supportive studies of a combined 574 patients.
Adverse events in the studies included somnolence, dizziness, headache, nausea, and fatigue.
Patients taking anti-epileptic drugs, including other gabapentin formulations, may be at increased risk for suicidal ideation and behavior, as well as potentially fatal multi-organ hypersensitivity, symptoms of which include fever, rash, and lymphadenopathy.
The drug should be tapered to once daily for a week before ceasing treatment to reduce risk of withdrawal seizure, the statement said.
The drug was initially approved for the treatment of moderate-to-severe primary restless legs syndrome in April 2011.