Which antipsychotic carries a black box warning for agranulocytosis?

Clozapine is the correct answer because it is specifically known to carry a black box warning for agranulocytosis, a potentially life-threatening condition characterized by a dangerously low level of neutrophils (a type of white blood cell). This risk necessitates regular monitoring of white blood cell counts in patients receiving clozapine therapy. The association between clozapine and agranulocytosis is significant enough that health care providers must adhere to strict guidelines regarding blood monitoring to ensure patient safety.

Other medications like chlorpromazine, buspirone, and lithium do not have this specific black box warning. Chlorpromazine, while an antipsychotic, does not have a similar risk profile in terms of agranulocytosis. Buspirone is an anxiolytic medication used primarily for anxiety and not associated with agranulocytosis. Lithium, often used as a mood stabilizer, is primarily monitored for its therapeutic index and renal function, rather than for blood cell counts. Thus, the distinct risk associated with clozapine makes it the only antipsychotic with this particular warning.