Cannabidiol inhibits Nav channels through two distinct binding sites

Cannabidiol (CBD), a major non-psychoactive phytocannabinoid in cannabis, is an effective treatment for some forms of epilepsy and pain. At high concentrations, CBD interacts with a huge variety of proteins, but which targets are most relevant for clinical actions is still unclear. Here we show that CBD interacts with Na(v)1.7 channels at sub-micromolar concentrations in a state-dependent manner. Electrophysiological experiments show that CBD binds to the inactivated state of Na(v)1.7 channels with a dissociation constant of about 50 nM. The cryo-EM structure of CBD bound to Na(v)1.7 channels reveals two distinct binding sites. One is in the IV-I fenestration near the upper pore. The other binding site is directly next to the inactivated "wedged" position of the Ile/Phe/Met (IFM) motif on the short linker between repeats III and IV, which mediates fast inactivation. Consistent with producing a direct stabilization of the inactivated state, mutating residues in this binding site greatly reduced state-dependent binding of CBD. The identification of this binding site may enable design of compounds with improved properties compared to CBD itself. Cannabidiol (CBD), the nonpsychoactive component in cannabis, is an effective treatment for epilepsy and pain. Here, authors explored the mode of action of CBD on hNa(v)1.7 channels through two distinct binding sites, suggesting a direct stabilization of the inactivated state of channels.