The 4"-fluoro analogue of the 3R,4S,βS isomer of ohmefentanyl is the most potent opioid yet discovered, possessing an analgesic potency approximately 18,000-fold greater than morphine.[3]

bananax pisze:

p'-fluoroohmfentanyl, ~20k silniejszy od morfiny i kilka/kilkanaście razy silniejszy od karfentanylu i etorfiny

"For whats been discovered, it would without a doubt be the 4-fluoro positional isomer of pharaohfentanyl. (4-fluoro-beta-hydroxy-3-methylfentanyl), with a stereoisomer scoring a proclaimed 18,100x (which means in-vivo reality in a human its probably half that).

In THEORY, a thiofentanyl variant of that may be even more potent, as thiofentanyls are generally more potent than their strictly fentanyl counterpacts (methylfentanyls, hydroxymethylfentanyls, etc.). Although not sure if thats even possible to produce.

I would predict hydroxymethylthiofentanyls would be more potent variants of the hydroxymethylfentanyls structure activity relationships.

Pharaohfentanyl is the positional isomer of Ohmefentanyl only the methyls in the 4 position instead of the 3 position (making it weaker but designer), identical in allother ways (i.e. carries the +30 minute duration increase from beta-hydroxy additions to methylfentanyls verse plain fentanyl).