Details
The U.S. Food and Drug Administration (FDA) conducted this study within the Sentinel System to assess the frequency of serum phosphate laboratory testing prior to and following administration of ferric carboxymaltose (FCM; Injectafer). Despite the addition of a Warnings and Precaution for symptomatic hypophosphatemia (HP) in 2020 and an update in 2023, there was concern that providers may not be sufficiently informed about the risk of HP and the need to monitor serum phosphate levels in patients at risk for chronic low serum phosphate and in those who receive a second course of therapy.
Using data from the Sentinel Distributed Database (spanning 2017 to 2024), this study found that only 8.9% of FCM infusion episodes had serum phosphate laboratory testing within 30 days prior to infusion, and 5.8% had serum phosphate laboratory testing within 30 days following infusion. A similar pattern of testing was observed in both the single- and multiple-infusion cohorts. Annual rates of serum phosphate laboratory testing increased only slightly over the study period: among single FCM infusion episodes, pre-infusion testing (within 30 days) rose from 5.9% (2017) to 13.7% (2024), and post-infusion testing (within 120 days) rose from 9.2% (2017) to 14.0% (2024). Among multiple FCM infusion episodes, pre-infusion testing increased from 6.1% (2017) to 12.7% (2024), and post-infusion testing (within 120 days) increased from 9.6% (2017) to 17.8% (2024).
Overall, fewer than 20% of FCM infusion episodes were associated with serum phosphate laboratory testing, regardless of whether a single infusion or multiple infusions were administered. FDA also reviewed reports from the FDA Adverse Events Monitoring System (AEMS, previously known as FAERS) and assessed drug utilization data. After the evaluation of results from all data sources, FDA mandated that a Boxed Warning for symptomatic hypophosphatemia be added to the labeling of FCM.