**Question:** All of the following are deliriant poisons, EXCEPT:

A. Phencyclidine (PCP)
B. D-tubocurarine
C. Chloral hydrate
D. Midazolam

**Core Concept:** Deliriant poisons are substances that cause a temporary alteration in consciousness, cognition, and perception. They can lead to confusion, agitation, and hallucinations.

**Why the Correct Answer is Right:** Midazolam is a benzodiazepine hypnotic and anxiolytic drug used for anesthesia induction, maintenance, and procedural sedation. Although it has sedative and anxiolytic properties, it does not cause delirium or alter consciousness.

**Why Each Wrong Option is Incorrect:**

A. Phencyclidine (PCP) is an anaesthetic agent that acts as an NMDA receptor antagonist, leading to dissociation, hallucinations, and altered consciousness, making it a deliriant poison.

B. D-tubocurarine is a neuromuscular blocking agent used for anesthesia induction, not causing delirium or altering consciousness, making it an incorrect deliriant poison.

C. Chloral hydrate is a sedative-hypnotic drug used for sedation and sleep induction, but it does not cause delirium or alter consciousness.

**Clinical Pearl:** A clinical pearl to remember deliriant poisons is "Don't confuse deliriants with depressants, sedatives, and anesthetics." Deliriants (PCP) cause delirium, while depressants (e.g., benzodiazepines) cause sedation and anxiolysis but not delirium, sedatives (e.g., chloral hydrate) cause sedation but not delirium, and anesthetics (e.g., D-tubocurarine) induce anesthesia but not delirium.

**Correct Answer:** D-tubocurarine (Option B) is not a deliriant poison because it is a muscle relaxant used for anesthesia induction, not causing delirium or altering consciousness.