Question

Serotonin syndrome may be precipitated by all of the following medications, except:

• A. Chlorpromazine
• B. Pentazocine
• C. Buspirone
• D. Meperidine

Hint:

One drug blocks serotonin receptors instead of boosting them.

Answer 1

The Correct Option is A

Step 1: Serotonin syndrome is caused by drugs that increase serotonergic activity, through more release, less reuptake, less breakdown, or direct receptor agonism.

Step 2: Buspirone is a 5-HT1A partial agonist, so it directly stimulates serotonin receptors and can precipitate the syndrome. Option C is a precipitant.

Step 3: Meperidine (pethidine) blocks serotonin reuptake and is a classic precipitant, especially with MAOIs. Option D is a precipitant.

Step 4: Pentazocine has weak serotonergic activity and has been reported to contribute to serotonin syndrome. Option B can be a precipitant.

Step 5: Chlorpromazine is a phenothiazine antipsychotic that BLOCKS serotonin and dopamine receptors. By antagonising 5-HT receptors it does not cause serotonin syndrome. In fact such drugs are used to manage it. So option A is the exception.

Conclusion: The drug that does not precipitate serotonin syndrome is chlorpromazine, option A.