Gabapentin enacarbil (Horizant () (), Regnite (in

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

)) is an

anticonvulsant Anticonvulsants (also known as antiepileptic drugs, antiseizure drugs, or anti-seizure medications (ASM)) are a diverse group of pharmacological agents used in the treatment of epileptic seizures. Anticonvulsants are also used in the treatme ...

and

analgesic An analgesic drug, also called simply an analgesic, antalgic, pain reliever, or painkiller, is any member of the group of drugs used for pain management. Analgesics are conceptually distinct from anesthetics, which temporarily reduce, and in s ...

drug of the

gabapentinoid Gabapentinoids, also known as α2δ ligands, are a class of drugs that are chemically chemical derivative, derivatives of the inhibitory neurotransmitter gamma-Aminobutyric acid (GABA) (i.e., GABA analogues) which Voltage-dependent calcium cha ...

class, and a

prodrug A prodrug is a pharmacologically inactive medication or compound that, after intake, is metabolized (i.e., converted within the body) into a pharmacologically active drug. Instead of administering a drug directly, a corresponding prodrug can be ...

gabapentin Gabapentin, sold under the brand name Neurontin among others, is an anticonvulsant medication primarily used to treat neuropathic pain and also for partial seizures of epilepsy. It is a commonly used medication for the treatment of neuropath ...

. It was designed for increased oral

bioavailability In pharmacology, bioavailability is a subcategory of absorption and is the fraction (%) of an administered drug that reaches the systemic circulation. By definition, when a medication is administered intravenously, its bioavailability is 100%. H ...

over gabapentin, and human trials showed it to produce extended release of gabapentin with almost twice the overall bioavailability, especially when taken with a fatty meal. Gabapentin enacarbil has passed human

clinical trial Clinical trials are prospective biomedical or behavioral research studies on human subject research, human participants designed to answer specific questions about biomedical or behavioral interventions, including new treatments (such as novel v ...

s for the treatment of

restless legs syndrome Restless legs syndrome (RLS), also known as Willis–Ekbom disease (WED), is a neurological disorder, usually chronic, that causes an overwhelming urge to move one's legs. There is often an unpleasant feeling in the legs that improves temporaril ...

, and initial results have shown it to be well tolerated and reasonably effective. Gabapentin enacarbil was denied approval by the U.S.

Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respo ...

(FDA) in February 2010, citing concerns about possible increased cancer risk shown by some animal studies. Similar concerns had been raised about gabapentin itself in the past, but were felt to be outweighed by its clinical utility as an anticonvulsant, whereas the treatment of restless legs syndrome was not seen to justify the same kind of risk. On April 6, 2011, Xenoport received FDA approval for Horizant (gabapentin enacarbil) for the treatment of moderate-to-severe restless legs syndrome. On June 7, 2012, the FDA approved Horizant for the treatment of

postherpetic neuralgia Postherpetic neuralgia (PHN) is neuropathic pain that occurs due to damage to a peripheral nerve caused by the reactivation of the varicella zoster virus ( herpes zoster, also known as shingles). PHN is defined as pain in a dermatomal distributi ...

in adults.

References

External links

* {{Portal bar , Medicine Anticonvulsants Analgesics Calcium channel blockers GABA analogues Gamma-Amino acids Prodrugs Drugs developed by GSK plc Cyclohexanes Carbamates Isobutyrate esters