SRD:Elixir of Truth

Elixir of Truth: This elixir forces the individual drinking it to say nothing but the truth for 10 minutes (Will DC 13 negates).

She is compelled to answer any questions put to her in that time, but with each question she is free to make a separate DC 13 Will save. If one of these secondary saves is successful, she doesn’t break free of the truth-compelling enchantment but also doesn’t have to answer that particular question. No more than one question can be asked each round. This is a mind-affecting compulsion enchantment.

Faint enchantment; CL 5th; Craft Wondrous Item, zone of truth; Price 500 gp.