Clinical consequences of analytical variance and calculation strategy in oral busulfan pharmacokinetics

► Busulfan displays significant inter-individual variability. ► Busulfan is monitored using AUC rather than individual drug concentrations. ► Both under-dosing and over-dosing of busulfan can lead to clinically significant adverse outcomes. ► Assay imprecision can significantly impact busulfan AUC and thus clinical decision making. ► Assay performance requirements are dependent on institutional approach to blood sampling intervals and AUC calculation.