(By Balaseshan) XenoPort Inc. (NASDAQ:XNPT) and GlaxoSmithKline plc (NYSE:GSK) said they received the United States Food and Drug Administration (FDA) approval for Horizant (gabapentin enacarbil) Extended-Release Tablets to manage postherpetic neuralgia in adults.
Postherpetic neuralgia is a neuropathic (nerve) pain syndrome that may result in disability in some people. PHN follows the healing of an outbreak of herpes zoster, commonly known as shingles. About 1 million people in the U.S. develop shingles each year. Of these, about 10% develop PHN.
The efficacy and safety of Horizant for the management of PHN was evaluated in a single 12-week principal efficacy trial, plus two supportive studies that all met their respective primary endpoints. The three clinical studies involved 574 adult patients from the U.S., Canada and Germany.
The recommended dosage for the management of PHN in adults is 600 mg twice daily. Treatment should be initiated at a dose of 600 mg in the morning for three days followed by 600 mg twice daily (1,200 mg/day) beginning on day four.
Doses must be adjusted in patients with impaired renal function. In the 12-week, controlled study in patients with PHN, somnolence and dizziness were the most frequently reported side effects.
Somnolence was reported in 10% of patients treated with 1,200 mg of Horizant per day compared with 8% of patients receiving placebo. Dizziness was reported in 17% of patients receiving 1,200 mg of Horizant per day compared with 15% of patients receiving placebo.
In association with GSK's first commercial sale of the product after approval for PHN, XenoPort is entitled to a milestone payment of $10 million from GSK.
XNPT closed Wednesday's regular session down 1.14% at $6.07, while GSK ended up 1.51% at $44.38.