Binding Characteristics and Analgesic Effects of Mirogabalin, a Novel Ligand for the α2δ Subunit of Voltage-Gated Calcium Channels

Mirogabalin ([(1R,5S,6S)-6-(aminomethyl)-3-ethylbicyclo[3.2.0]hept-3-en-6-yl]acetic acid), a novel ligand for the α₂δ subunit of voltage-gated calcium channels, is being developed to treat pain associated with diabetic peripheral neuropathy and postherpetic neuralgia. In the present study, we investigated the in vitro binding characteristics and in vivo analgesic effects of mirogabalin compared with those of pregabalin, a standard α₂δ ligand. Mirogabalin showed potent and selective binding affinities for the α₂δ subunits, while having no effects on 186 off-target proteins. Similar to pregabalin, mirogabalin did not show clear subtype selectivity (α₂δ-1 vs. α₂δ-2) or species differences (human vs. rat). However, in contrast to pregabalin, mirogabalin showed greater binding affinities for human α₂δ-1, human α₂δ-2, rat α₂δ-1, and rat α₂δ-2 subunits; further, it had a slower dissociation rate for the α₂δ-1 subunit than the α₂δ-2 subunit. Additionally, in experimental neuropathic pain models, partial sciatic nerve ligation rats and streptozotocin-induced diabetic rats, mirogabalin showed more potent and longer lasting analgesic effects. In safety pharmacological evaluations, mirogabalin and pregabalin inhibited rota-rod performance and locomotor activity in rats; however, the safety indices of mirogabalin were superior to those of pregabalin. In conclusion, mirogabalin shows potent and selective binding affinities for the human and rat α₂δ subunits, and slower dissociation rates for the α₂δ-1 subunit than the α₂δ-2 subunit. It shows potent and long-lasting analgesic effects in rat models of neuropathic pain, and wider safety margins for side effects of the central nervous system. These properties of mirogabalin can be associated with its unique binding characteristics.