Figure 1. Schematic diagram for combination effect analysis.

Drug combinations were analyzed for their ability to affect dose reduction and synergy. First, individual drugs, either free or encapsulated, were used to create dose response curves using the TZM-bl assay. These curves were fit to a sigmoid curve using nonlinear least squares regression to estimate drug IC₅₀ and the Hill slope. Next, combinations of drugs at their equipotency ratio (1∶1 ratios of IC₅₀ values) were used to create similar curves using the TZM-bl assay. These were also fit to a sigmoid curve using nonlinear least squares regression to estimate the IC₅₀ and Hill slope of the combination. Finally, comparison of IC₅₀ values combinations were used to estimate dose reduction. The median-effect analysis was performed to measure combination effects.