USMLE Step 1 Question 397

Question:

A patient in the psychiatry wards has been abusing a particular drug with a very low safety margin. This drug causes respiratory depression, slowness of movement and slurred speech. His withdrawal episodes have included rebound anxiety, seizures and wildly fluctuating hypertension. This drug most likely belongs to which of the following classes?

Correct Answer: B.  Barbiturates

Barbiturates (B) produce respiratory depression and slurred speech with the withdrawal effects described in the question stem.

Cardiovascular collapse is also a potentially life threatening consequence of withdrawal. Notably, barbiturates have a very low safety margin.

Amphetamines (A) produce the opposite effects described, including agitation, tachycardia, euphoria, and prolonged attentiveness.

Benzodiazepines (C) would produce similar effects as barbiturates, but are widely used because they have a much greater therapeutic window.

(D) Hallucinogens and (E) Opioids possess a more complex abuse profile can themselves cause anxiety or seizures, respectively.