A 26-year-old man with treatment-resistant schizophrenia fails two adequate trials of antipsychotics. He is started on clozapine. After 6 weeks, his absolute neutrophil count drops to 900/mm³. The CORRECT management is:

• A Reduce clozapine dose by 50% and recheck in one week
• B Stop clozapine immediately and never rechallenge
• C Add G-CSF and continue clozapine at reduced dose
• D Stop clozapine immediately; rechallenge is possible only if ANC was 500–999 (mild-moderate neutropenia) after haematology consultation ✓

Explanation

ANC 500–999/mm³ represents moderate neutropenia in the REMS (Risk Evaluation and Mitigation Strategy) framework for clozapine. Clozapine must be stopped, but unlike severe neutropenia (ANC <500, which mandates permanent discontinuation), moderate neutropenia allows careful rechallenge under haematology supervision once ANC recovers to >1000. The CPMS/national guidelines define thresholds precisely: 'red' (ANC <500) = permanent discontinuation; 'amber' (ANC 500–999) = stop and reassess.

Reference: Kaplan & Sadock's Synopsis of Psychiatry, 11th ed.

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