W-18

W-18 is a small molecule research compound originally synthesized in the 1980s at the University of Alberta as part of an academic initiative to discover new analgesics. It was one of 32 compounds (W-1 to W-32) developed for potential pain management. Although early animal studies in mice suggested analgesic activity, the compound was never advanced to clinical trials or commercialized by the pharmaceutical industry. In the 2010s, W-18 re-emerged as a designer drug on the illicit market, where it was frequently mischaracterized as a highly potent synthetic opioid. However, comprehensive pharmacological studies published in 2017 demonstrated that W-18 lacks significant activity at mu, delta, kappa, and nociceptin opioid receptors. Instead, it shows only weak affinity for the Translocator protein (TSPO), formerly known as the peripheral benzodiazepine receptor, and sigma receptors. Due to its presence in the illicit drug market, it has been classified as a controlled substance in several jurisdictions, including Canada.

Other names

4-chloro-N-[1-[2-(4-nitrophenyl)ethyl]-2-piperidinylidene]-benzenesulfonamide