Combining drugs for therapy: AUC based approach

Drugs are combined to achieve a specific pharmacodynamic objective

a) increase efficacy (eg cancer treatment)

b)  reduce development of resistance (eg infection treatment)

The choice of drugs to be combined to treat a specific disorder will depend on the drug-drug interactions at the pharmacokinetic level and at the pharmacodynamic level.

There are a few approaches to decide on the combination of drugs. One approach is to assess changes in pharmacodynamic parameters (Emax, EC50) of the individual drugs when combined. The AUC based approach is illustrated with this hypothetical situation. In such an approach the approved doses of the individual drugs in the combination can reduce or remain unchanged based on the changes in PD parameters and the objective of the treatment.