The anti-seizure drug Retigabine, also known as Potiga, originally developed by Valeant Pharmaceuticals and subsequently licensed to Glaxo was approved by the FDA in June 2011; it won regulatory approval in the EU a several months earlier in January. The FDA deemed it a controlled substance, requiring a delay for the U.S. DEA to classify the drug.
Retigabine is a new class of drugs that acts on neurons’ potassium channels rather than the more typical sodium or chloride channels. It is a KCNQ/Kv7 potassium channel activator which functions by enhancing potassium currents via stabilizing the open conformation of the Kv7.2-7.3 channels. Retigabine has been shown to accelerate the activation of neuronal resting potentials while slowing deactivation of these currents. Studies also indicate that the compound can act as a GABA enhancer by amplifying the production of GABA in cortical neurons.
Development of Retigabine began with a screening campaign in the 1980s. Three randomized Phase III studies involving a total of 1,239 patients were required to gain approval. In all three trials, the drug demonstrated a meaningful decrease in seizure frequency compared to placebo.
The novel mechanism of action makes for a nice add-on drug. But like the many approvals before it, Retigabine is unlikely to aid the one-third of patients resistant to treatment.
We now have an arsenal of some 20 anti-epileptic drugs, yet that same patient population remains underserved. It is time to take a hard look at our standard preclinical models- they obviously do not represent these seizure types.
There is money to be made for those who succeed. The epilepsy drug market in 2009 weighed in at $8.1 billion according to Thomson Reuters.