(1) The defendant must not know, or have reason to know, that the prescribed drug is likely to have an intoxicating effect. If the defendant knows, or has reason to know, that the prescribed drug will have an intoxicating effect, then he is voluntarily intoxicated and may plead his voluntary intoxication as a partial defense.(2) The prescribed drug, and not some other intoxicant, is in fact the cause of defendant's intoxication at the time of his alleged criminal conduct.(causation between drugs and intoxication)(3) The defendant, due to involuntary intoxication, is temporarily insane.(causation between intoxication and insane)