Yes, THIOPENTAL is a Scrabble word!

Letter values in Scrabble US: T 1, H 4, I 1, O 1, P 3, E 1, N 1, T 1, A 1, L 1.

Is it a valid word?

THIOPENTAL is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

barbiturate that is a hygroscopic powder (trade name Pentothal) that is a strong barbiturate that acts rapidly; induces a relaxed state when injected as a general anesthetic

Also: thiopental sodium, thiopentobarbital sodium.

Not playable in Scrabble US: PENTOTHAL.