Which of the following drugs is a benzodiazepine tranquilizer?

• A. Xylazine
• B. Diazepam
• C. Pentobarbital
• D. Promazine

Answer: (B)

Benzodiazepines work by enhancing the inhibitory effect of GABA at the GABA-A receptor, which produces sedation, reduced anxiety, muscle relaxation, and anticonvulsant effects. Diazepam is a classic example of this class and is commonly used in lab animals as a tranquilizer for short-term sedation and seizure control. Xylazine is an alpha-2 adrenergic agonist with sedative and analgesic properties, not a benzodiazepine. Pentobarbital is a barbiturate with a different mechanism of action for CNS depression. Promazine is a phenothiazine tranquilizer with antiemetic effects, also not a benzodiazepine. So diazepam is the benzodiazepine tranquilizer in this list.