Gabapentin

Gabapentin, sold under the brand name Neurontin among others, is an anticonvulsant medication used to treat partial seizures, neuropathic pain, hot flashes, and restless legs syndrome. It is recommended as one of a number of first-line medications for the treatment of neuropathic pain caused by diabetic neuropathy, postherpetic neuralgia, and central neuropathic pain. About 15% of those given gabapentin for diabetic neuropathy or postherpetic neuralgia have a measurable benefit. Gabapentin is taken by mouth. Common side effects include sleepiness and dizziness. Serious side effects include an increased risk of suicide, aggressive behavior, and drug reactions. It is unclear if it is safe during pregnancy or breastfeeding. Lower doses are recommended in those with kidney disease associated with a low kidney function. Gabapentin is a gabapentinoid. It has a molecular structure similar to that of the neurotransmitter γ-aminobutyric acid (GABA) and acts by inhibiting certain calcium channels. Gabapentin was first approved for use in 1993. It has been available as a generic medication in the United States since 2004. The wholesale price in the developing world as of 2015 was about US$10.80 per month; in the United States, it was US$100 to US$200. In 2016, it was the 11th most prescribed medication in the United States, with more than 44 million prescriptions. During the 1990s, Parke-Davis, a subsidiary of Pfizer, began using a number of illegal techniques to encourage physicians in the United States to use gabapentin for unapproved uses. They have paid out millions of dollars to settle lawsuits regarding these activities. Gabapentin is FDA approved to treat seizures and neuropathic pain. It is primarily administered by mouth, with a study showing that 'rectal administration is not satisfactory'. It is also commonly prescribed for many off-label uses, such as treatment of anxiety disorders, insomnia, and bipolar disorder. About 90% of usage is for off-label conditions. There are, however, concerns regarding the quality of the trials conducted and evidence for some such uses, especially in the case of its use as a mood stabilizer in bipolar disorder. Gabapentin is approved for treatment of focal seizures and mixed seizures. There is insufficient evidence for its use in generalized epilepsy. A 2018 review found that gabapentin was of no benefit in sciatica nor low back pain. A 2010 European Federation of Neurological Societies task force clinical guideline recommended gabapentin as a first-line treatment for diabetic neuropathy, postherpetic neuralgia, or central pain. It found good evidence that a combination of gabapentin and morphine or oxycodone or nortriptyline worked better than either drug alone; the combination of gabapentin and venlafaxine may be better than gabapentin alone. A 2017 Cochrane review found evidence of moderate quality showing a reduction in pain by 50% in about 15% of people with postherpetic neuralgia and diabetic neuropathy. Evidence finds little benefit and significant risk in those with chronic low back pain. It is not known if gabapentin can be used to treat other pain conditions, and no difference among various formulations or doses of gabapentin was found.