The highest risk period for agranulocytosis after starting an antipsychotic is during which timeframe?

The highest risk period for agranulocytosis after starting an antipsychotic is during which timeframe?

• A. After 5 years
• B. First 26 weeks
• C. After 1 year
• D. Any time equally

Answer: (B)

Agranulocytosis from antipsychotics, especially clozapine, tends to occur most often early after starting treatment. The immune or marrow-suppressive effects are most pronounced in the initial months, so the highest risk window is the first roughly six months, or 26 weeks. This is why close monitoring of absolute neutrophil counts is required during this period. After this early phase, the incidence drops, though rare cases can still occur. The other timeframes—late after years or a constant equal risk over time—do not reflect the pattern seen with this adverse effect.

Agranulocytosis from antipsychotics, especially clozapine, tends to occur most often early after starting treatment. The immune or marrow-suppressive effects are most pronounced in the initial months, so the highest risk window is the first roughly six months, or 26 weeks. This is why close monitoring of absolute neutrophil counts is required during this period. After this early phase, the incidence drops, though rare cases can still occur. The other timeframes—late after years or a constant equal risk over time—do not reflect the pattern seen with this adverse effect.