FDA clears GlaxoSmithKline's Horizant for PHN

The US Food and Drug Administration (FDA) has approved UK Pharma giant GlaxoSmithKline’s (LSE: GSK) Horizant (gabapentin enacarbil) extended-Release Tablets for the management of postherpetic neuralgia (PHN) in adults.

The drug is the subject of a 2007 collaboration with USA-based XenoPort (Nasdaq: XNPT), worth a potential $640 million to the latter firm. Horizant is not approved or licensed outside the USA for PHN, but it was approved for the treatment of moderate-to-severe primary Restless Legs Syndrome (RLS) in adults in the USA in April 2011. 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 the UK company.

However, XenoPort's shares fell as much as 13% on concerns that a contractual dispute between the two companies over Horizant could now take longer to resolve, noted RBC Capital analyst Michael Yee, quoted by the Chicago Tribune.