Drugging the undruggable: gabapentin, pregabalin and the calcium channel α2δ subunit.

In the post-genomic era, the idea of using the sequence of a protein to determine its potential role as a drug target has gained currency. The goal of this approach to drug discovery is to use the sequence of a protein that is known to bind a specific ligand or drug, along with the known structure of the ligand binding site, to predict other similar proteins that are also "druggable". Gabapentin (Neurontin) and pregabalin (Lyrica) are drugs currently in the clinic that were developed based on the hypothesis that generating non-hydrolyzable analogs of GABA would lead to the development of antiepileptic agents. While these compounds are indeed good anticonvulsants, their activity is surprisingly not due to activity in the GABAergic system. By purifying the protein to which gabapentin bound, and determining its identity as the alpha(2)delta(1) subunit of voltage gated calcium channels, it was possible to make progress in developing new compounds with similar activities to gabapentin, including pregabalin. The recognition of the alpha(2)delta(1) subunit as the receptor for these drugs also meant that related proteins, such as alpha(2)delta(3), may be interesting targets for novel pain therapeutics.