Thiopental and Truth serum

Thiopental noun - 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.

Truth serum and thiopental are semantically related. In some cases you can use "Truth serum" instead a noun "Thiopental".

Truth serum noun - An intravenous anesthetic drug that has a hypnotic effect; induces relaxation and weakens inhibitions; is believed to induce people to talk freely.

Thiopental and truth serum are semantically related. Sometimes you can replace term "Thiopental" with "Truth serum", this terms are similar.