ohmefentanyl

As with other 3-substituted fentanyl derivatives such as ohmefentanyl, the stereoisomerism of lofentanil is very important, with some stereoisomers being much more potent than others.

Other opioid analogues even more potent still than 3-MF are known, such as carfentanil and ohmefentanyl, but these are significantly more difficult to manufacture than 3-methylfentanyl and have not been so well accepted as street drugs.

The 4"-fluoro analogue (i.e. substituted on the phenethyl ring) of the 3R,4S,βS isomer of ohmefentanyl is one of the most potent opioid agonists yet discovered, possessing an analgesic potency approximately 18,000-fold greater than morphine.