Related Experiment Video
Updated: Sep 8, 2025

Diagonal Method to Measure Synergy Among Any Number of Drugs
Published on: June 21, 2018
Log-probit accompanied with Tallarida and Chou-Talalay-Martin methods in an isobolographic analysis of interactions
Jarogniew J Łuszczki1, Katarzyna Gustaw-Rothenberg2, Magdalena Florek-Łuszczki2
1Department of Occupational Medicine, Medical University of Lublin, Lublin, Poland. jarogniew.luszczki@umlub.pl.
Background:
The isobolographic analysis is a gold standard in the assessment of interactions between drugs in experimental studies. Although some isobolographic approaches are available, the most popular methods to characterize drug-drug interactions are the log-probit method accompanied with statistical analysis of interactions (by Tallarida) and the method based on mass-action law using CompuSyn software (elaborated by Chou-Talalay-Martin). The aim of this study was to compare the results from these two isobolographic approaches.
Methods:
Two isobolographic methods (log-probit associated with Tallarida statistics and Chou-Talalay-Martin) were applied to analyze the interaction between two antiseizure medications - clonazepam and lamotrigine in the mouse maximal electroshock-induced seizure model.
Results:
Both isobolographic approaches confirmed that the combination of clonazepam with lamotrigine produced synergistic interaction and allowed for detailed characteristics of the interaction at various effect levels for the two-drug mixture. Calculation of the combination index values (at various effect levels) confirmed that synergy slightly decreased when the antiseizure effect increased (combination index values increased from 0.44 for 16% to 0.65 for 84%).
Conclusions:
The log-probit method with statistical analysis of data (by Tallarida) was more subtle and precise in the assessment of the synergistic interaction, whereas the isobolographic analysis by Chou-Talalay-Martin offered more automatic options facilitating visualization of the interaction.
Related Concept Videos
Agonism and Antagonism: Quantification
To quantify these effects, researchers use a dose-response curve, which provides valuable information about the potency and efficacy of a drug. Potency refers to...
Antiepileptic Drugs: GABAergic Pathway Potentiators
The key GABA pathway potentiators used in epilepsy management are as follows.
Benzodiazepines are a well-known class of drugs used for...
Antiepileptic Drugs: Modulators of Neurotransmitter Release Mediated by SV2A Protein
SV2A is a transmembrane glycoprotein located predominantly in the brain, modulating the release of neurotransmitters for neuronal communication. Both levetiracetam and brivaracetam exhibit a high affinity for...
Analysis Methods of Pharmacokinetic Data: Model and Model-Independent Approaches
The model approach uses mathematical models to describe changes in drug concentration over time. Pharmacokinetic models help characterize drug behavior in patients, predict drug concentration in the body fluids, calculate optimum dosage regimens, and evaluate the risk of toxicity. However, ensuring that the model fits the experimental data accurately...
Quantitative Aspects of Drug-Receptor Interaction
Antiepileptic Drugs: Potassium Channel Activators
Ezogabine has gained approval as an adjunctive treatment...

