W-18
Last August, Canadian police seized 110 illegal fentanyl pills at a home in Alberta province. Yesterday, Global News reported that some of the pills have tested positive for an extremely potent opioid called W-18.
This is certainly a disturbing development, since W-18 is a μ-receptor agonist 100 times more potent than fentanyl. According to B.C. Centre for Disease Control, W-18 is one of a series of 32 synthetic opioids discovered in the 1980s at the University of Alberta. W1 thru W19 are pure μ-receptor agonists; W20 thru W32 are agonist-antagonists (as is buprenorphine.)  W-18 seems to be the most powerful agonist of the group.
The ‘W’ compounds have never been used clinically, and there has been virtually no scientific study of their actions, adverse effects, or reve…