Discovered by XenoPort, gabapentin enacarbil, previously known as XP13512, is a patented new chemical entity that utilizes naturally-occurring, high-capacity nutrient transporters in the gastrointestinal tract to generate active, efficient absorption into the body. Once absorbed, gabapentin enacarbil is rapidly converted into gabapentin, which binds to specific proteins that regulate neuronal activity, and is thereby thought to inhibit unnecessary excitatory neurological activity.

We have licensed rights to develop and commercialize gabapentin enacarbil to Astellas Pharma Inc. in Japan and five Asian countries and to GlaxoSmithKline in the United States. In the United States, gabapentin enacarbil is being developed as a potential treatment for patients with post-herpetic neuralgia. In Japan, gabapentin enacarbil is being developed as a potential treatment for patients with restless legs syndrome.

Neuropathic Pain

Neuropathic pain is pain that results from damage to nerves. The damage may result from a variety of causes, including injury or illnesses such as diabetes, HIV and shingles. Gabapentin enacarbil is being developed in the United States as a potential treatment for patients with one form of chronic neuropathic pain called post-herpetic neuralgia (PHN). PHN is a complication of shingles, a painful outbreak of rash or blisters on the skin caused by a reactivation of the same virus that causes chicken pox. PHN is often characterized as constant stabbing, burning or electric shock-like sensations in the area affected by shingles after the rash has cleared. Approximately 10% to 15% of all patients with shingles develop PHN, which can persist for many years.

Restless Legs Syndrome

Restless legs syndrome is a neurological condition that causes an irresistible urge to move the legs. This urge is usually accompanied by unpleasant sensations of burning, creeping, tugging or tingling inside the patients’ legs, ranging in severity from uncomfortable to painful. These symptoms typically begin or worsen during periods of rest or inactivity, particularly when lying down or sitting, and may be temporarily relieved by movement, such as walking or massaging the legs. Symptoms often worsen at night, and disturbed sleep is a common result of restless legs syndrome. Left untreated, restless legs syndrome may cause exhaustion, daytime fatigue, inability to concentrate and impaired memory. Gabapentin enacarbil is being developed in Japan by our partner, Astellas, as a potential treatment for restless legs syndrome.