Which drug is associated with both pancytopenia and thrombocytopenia?

• A. Clozapine
• B. Quetiapine
• C. Olanzapine
• D. Risperidone

Answer: (A)

Bone marrow suppression is a key adverse effect to recognize with certain antipsychotics, and one drug in particular is well known for this severe hematologic risk. Clozapine carries a strong association with neutropenia and agranulocytosis, and in some cases this can extend to pancytopenia (low red cells, white cells, and platelets) or isolated thrombocytopenia. This happens because the drug can suppress multiple blood cell lineages through bone marrow effects, or trigger immune-mediated destruction of cells.

The other antipsychotics listed have far less propensity for such serious cytopenias; they can cause mild effects in some individuals but are not characteristically linked with pancytopenia or thrombocytopenia to the same extent as clozapine.

In clinical practice, this is why clozapine requires regular blood monitoring and clear thresholds to hold or discontinue therapy if the white cell or neutrophil counts drop, with attention to any signs of infection, bleeding, or anemia.