– QAQ dichloride is a photoswitchable compound that blocks voltage-gated Na v and K v channels. Its channel-blocking activity is observed in the trans form of the azobenzene photoswitch, while the cis form does not exhibit this effect. This compound is membrane-impermeant and selectively enters pain-sensing neurons expressing endogenous import channels. QAQ dichloride functions as a light-sensitive analgesic and provides a valuable tool for investigating signaling mechanisms involved in acute and chronic pain [1] [2].