What is the most severe side effect associated with Trimethoprim/Pyrimethamine?

What is the most severe side effect associated with Trimethoprim/Pyrimethamine?

• A. Aplastic Anemia
• B. Pancytopenia
• C. Leukopenia
• D. Thrombocytopenia

Answer: (A)

These drugs are antifolates that disrupt DNA synthesis in rapidly dividing cells, especially bone marrow. That makes bone marrow particularly susceptible to injury, leading to cytopenias. Among hematologic adverse effects, aplastic anemia stands out as the most severe because it reflects bone marrow failure with inadequate production of red cells, white cells, and platelets. This can cause life-threatening anemia, infections, and bleeding, which is why it’s considered the most serious toxicity. Other reductions in blood cells ( leukopenia, thrombocytopenia, or pancytopenia) are serious but do not represent the same level of marrow failure.

These drugs are antifolates that disrupt DNA synthesis in rapidly dividing cells, especially bone marrow. That makes bone marrow particularly susceptible to injury, leading to cytopenias. Among hematologic adverse effects, aplastic anemia stands out as the most severe because it reflects bone marrow failure with inadequate production of red cells, white cells, and platelets. This can cause life-threatening anemia, infections, and bleeding, which is why it’s considered the most serious toxicity. Other reductions in blood cells ( leukopenia, thrombocytopenia, or pancytopenia) are serious but do not represent the same level of marrow failure.