This protocol describes how to study all possible combinations that can be obtained between four drugs in one single experiment. This method is based on the standard 96-well plate micro dilution assay and the calculation of fractional inhibitory concentrations (FICs) to evaluate the results.
Isber, C., Stockman, D. L., Daoud, Z. Quadruple-Checkerboard: A Modification of the Three-Dimensional Checkerboard for Studying Drug Combinations. J. Vis. Exp. (173), e62311, doi:10.3791/62311 (2021).