Gabapentin enacarbil is also in development for treating postherpetic neuralgia.
FDA approved XenoPort and U.S. partner GlaxoSmithKline’s (GSK) Horizant™ (gabapentin enacarbil) extended-release tablets for the treatment of moderate-to-severe primary restless legs syndrome in adults. Regulatory clearance in the U.S. was based on data from two 12-week studies. XenoPort claims the drug is the first in its class to be approved for the treatment of moderate-to-severe restless legs syndrome.
XenoPort and GSK are separately carrying out Phase II development of gabapentin enacarbil in the U.S. for the treatment of post-herpetic neuralgia. The drug is being developed in Japan and other Asian countries for the restless legs syndrome indication by Astellas. Regulatory review in Japan is in progress.
Under an amendment to the Horizant deal with GlaxoSmithKline, XenoPort now has the right to pursue development of the drug for certain other indications in the U.S. GSK remains responsible for commercialization of Horizant in the U.S. for all indications. In addition, XenoPort has reacquired all non-U.S. rights to the gabapentin enacarbil that were previously granted to GSK, excluding the Astellas territory.