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Updated: Mar 15, 2026

Diagonal Method to Measure Synergy Among Any Number of Drugs
Published on: June 21, 2018
Assessment of non-linear combination effect terms for drug-drug interactions
Gilbert Koch1,2, Johannes Schropp3, William J Jusko4
1Pediatric Pharmacology and Pharmacometrics, University of Basel, Children's Hospital (UKBB), Spitalstrasse 33, 4056, Basel, Switzerland. gilbert.koch@ukbb.ch.
Abstract:
Drugs interact with their targets in different ways. A diversity of modeling approaches exists to describe the combination effects of two drugs. We investigate several combination effect terms (CET) regarding their underlying mechanism based on drug-receptor binding kinetics, empirical and statistical summation principles and indirect response models. A list with properties is provided and the interrelationship of the CETs is analyzed. A method is presented to calculate the optimal drug concentration pair to produce the half-maximal combination effect. This work provides a comprehensive overview of typically applied CETs and should shed light into the question as to which CET is appropriate for application in pharmacokinetic/pharmacodynamic models to describe a specific drug-drug interaction mechanism.
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