Delayed-onset neutropenia with divalproex sodium.

Area of Science:

• Neuroscience
• Pharmacology
• Hematology

Background:

• Delayed-release divalproex sodium (DVPX) is a commonly prescribed antiepileptic and mood-stabilizing drug.
• Therapeutic drug monitoring (TDM) of serum valproic acid levels is standard practice.
• Hematologic monitoring, including white blood cell (WBC) and absolute neutrophil count (ANC), is also performed.

Observation:

• A 45-year-old male on DVPX for nearly 8 years developed neutropenia (ANC <1800 cells/microL) after a dosage adjustment.
• The patient's ANC dropped to 1199 cells/microL, despite prior normal counts and serum valproic acid levels.
• Neutropenia was suspected to be DVPX-related based on the Naranjo probability scale.

Findings:

• This case presents a rare instance of late-onset neutropenia associated with DVPX, occurring almost 8 years into therapy.
• The patient experienced laboratory-confirmed neutropenia without any clinical manifestations or complications.
• Discontinuation of DVPX led to a rapid recovery of WBC and ANC levels.

Implications:

• This case highlights the importance of continued hematologic monitoring, even in patients on long-term DVPX therapy.
• Late-onset DVPX-associated neutropenia, though rare, can occur and necessitates vigilant monitoring.
• Early detection through TDM allowed for timely intervention and prevented adverse clinical outcomes.