Flupirtine

# Overview
Flupirtine is an aminopyridine that functions as a centrally acting non-opioid analgesic. It first became available in Europe in 1984, and is sold mainly under the names Katadolon, Trancolong, Awegal, Efiret, Trancopal Dolo, and Metanor. Flupirtine is sold by Intas Pharma under the brand name Pruf in India. Like nefopam, it is unique among analgesics in that it is a non-opioid, non-NSAID, non-steroidal centrally acting analgesic. In 2010 the chemically related drug (the difference being that the pyridine group in flupirtine is replaced with a phenyl group) retigabine (INN; ezogabine ) was approved by the FDA as an anticonvulsant for the treatment of refractory partial-onset seizures in treatment-experienced patients. Retigabine also works by opening the neuronal KCNQ/Kv7 potassium channel, just like flupirtine.

# History
Flupirtine was originally developed by Asta Medica, with the synthesis of the compound and the development of the drug described in patents from the 1970s to the 2000s.
It was approved for the treatment of pain in 1984 in Europe. However, it has never been introduced to the United States market for any indication. In 2008, Adeona Pharmaceuticals, Inc. (now called Synthetic Biologics, Inc.) obtained an option to license issued and patent pending applications relating to flupirtines use in the treatment of ophthalmic indications, particularly retinitis pigmentosa.

# Mechanism of Action
Flupirtine is a selective neuronal potassium channel opener that also has NMDA receptor antagonist and GABAA receptor modulatory properties.

# Uses
Flupirtine is used as an analgesic for acute and chronic pain, in moderate-to-severe cases. Its muscle relaxant properties make it popular for back pain and other orthopedic uses, but it is also used for migraines, in oncology, postoperative care, and gynecology.
Flupirtine has been noted for its neuroprotective properties, and it is being investigated for possible use in CreutzfeldtJakob disease, Alzheimer's disease, and multiple sclerosis. It has also been proposed as a possible treatment for Batten disease.
Flupirtine underwent a clinical trial as a treatment for multiple sclerosis and fibromyalgia. Flupirtine showed promise for fibromyalgia due to its different action than the three approved by U.S. FDA drugs: Lyrica (pregabalin), Savella (milnacipran), and Cymbalta (duloxetine). Additionally, there are case reports regarding flupirtine as a treatment for fibromyalgia. Adeona Pharmaceuticals (now called Synthetic Biologics) sub-licensed its patents for using flupirtine for fibromyalgia to Meda AB in May 2010.

# Side Effects
The most serious side effect is frequent hepatotoxicity which prompted regulatory agencies to issue several warnings and restrictions.
Flupirtine is devoid of negative psychological or motor function effects, or effects on reproductive function.

# Abuse and Dependence
Although some studies have reported flupirtine has no addictive properties, there was suggestion that it may possess some abuse potential and liability. There were at least two registered cases of flupirtine abuse. Drug tolerance does not develop in most cases; however, tolerance may develop in single cases.