W-18 (drug)

W-18 is an extremely potent synthetic opioid analgesic that emerged on the illicit drug market in the 2010s. It is structurally distinct from other common opioid analgesics such as morphine, fentanyl, and heroin, belonging to a class of compounds known as adamantyl benzamides.

W-18 was originally synthesized in 1984 by researchers at the University of Alberta, who were investigating non-addictive opioid analgesics. While its analgesic properties were recognized, it was not pursued for pharmaceutical development due to its potential for abuse and the availability of other, less problematic pain relievers.

The resurgence of W-18 occurred when it began to be manufactured and distributed illicitly as a "research chemical" and later as a cutting agent in other drugs, particularly heroin and fentanyl. Its high potency posed a significant risk of overdose, as even small amounts could be lethal, especially when users were unaware of its presence. Unlike fentanyl and some of its analogs, W-18 is not responsive to naloxone in some individuals.

The effects of W-18 are similar to those of other opioids, including pain relief, euphoria, sedation, and respiratory depression. However, due to its potency, the risk of respiratory depression and overdose is significantly elevated.

W-18 has been subject to legislative action in many countries, including Canada and the United States, where it has been classified as a Schedule I controlled substance, meaning it has a high potential for abuse and no currently accepted medical use. Testing for W-18 is not commonly included in standard drug screenings, further complicating its detection and contributing to the challenge of managing its use and preventing overdoses.