P-1963. Signal Detection of Antibiotic-Associated Hematologic Adverse Events: Aplastic Anemia, Agranulocytosis, and Pancytopenia in the FAERS Database

Background Antibiotics are among the most commonly prescribed drug classes worldwide. While generally safe, several antibiotics have been implicated in rare but life-threatening hematologic adverse events (AEs), including aplastic anemia, agranulocytosis, and pancytopenia. These events are often underrecognized due to their delayed onset and non-specific clinical presentation. This study aimed to identify signal strength and antibiotic associations for serious hematologic AEs using post-marketing data from the U.S. FDA Adverse Event Reporting System (FAERS).Forest Plot: Hematologic Adverse Events Associated with Antibiotics (FAERS 2010–2023)This forest plot presents Reporting Odds Ratios (RORs) with 95% confidence intervals for antibiotic-associated hematologic adverse events. Chloramphenicol showed the strongest signal for aplastic anemia (ROR: 12.56), followed by linezolid for pancytopenia (ROR: 7.88) and trimethoprim-sulfamethoxazole for agranulocytosis (ROR: 5.41). These findings reinforce the need for routine hematologic monitoring during therapy with high-risk antibiotics. Methods A retrospective pharmacovigilance analysis was conducted using FAERS data from January 2010 to December 2023. Reports listing commonly used antibiotics (e.g., chloramphenicol, linezolid, trimethoprim-sulfamethoxazole, beta-lactams, fluoroquinolones, and macrolides) were screened for hematologic-related MedDRA Preferred Terms including “aplastic anemia,” “agranulocytosis,” and “pancytopenia.” Disproportionality analysis was performed using Reporting Odds Ratios (ROR) and 95% confidence intervals (CI). A signal was considered significant if the lower bound of the CI >1 and ≥3 reports existed. Results Out of 5,284 relevant hematologic AE reports, the highest signals were detected for chloramphenicol and aplastic anemia (ROR: 12.56, 95% CI: 10.71–14.73), followed by linezolid and pancytopenia (ROR: 7.88), and trimethoprim-sulfamethoxazole and agranulocytosis (ROR: 5.41). Beta-lactams and fluoroquinolones showed lower but statistically significant signals. Most events occurred within 2–4 weeks of antibiotic initiation, and approximately 21.6% required hospitalization or resulted in life-threatening outcomes. Conclusion This FAERS-based analysis reveals strong and class-specific signals for hematologic toxicity linked to antibiotics. Chloramphenicol, linezolid, and sulfonamides demonstrated the highest risk. Clinicians should maintain vigilance for hematologic monitoring in prolonged or high-dose therapy. These findings support ongoing pharmacovigilance and the inclusion of hematologic safety warnings in prescribing guidelines. Disclosures All Authors: No reported disclosures