Yes, FENTANYLS is a Scrabble word!

Letter values in Scrabble US: F 4, E 1, N 1, T 1, A 1, N 1, Y 4, L 1, S 1.

Is it a valid word?

FENTANYLS is a valid word in the official Scrabble dictionary (US) and the UK Scrabble Dictionary, but not in Words with Friends (ENABLE).

trade names of a narcotic analgesic that can be inhaled and that acts on the central nervous system and may become addictive; used as a veterinary anesthetic and with other drugs before, during, and after surgery; also used as a nonlethal gas to incapacitate people in hostage situations; also abused as a recreational drug

Not playable in Scrabble US: SUBLIMAZE.