Modeling Delayed Outcomes in PK Studies Using Delay Differential Equations

Delays are ubiquitous in the pharmacokinetics (PK) and pharmacodynamics (PD) studies. Transit compartment models, described by systems of ordinary differential equations, have been widely used to describe delayed outcomes in PK and PD studies. The obvious disadvantage for this type of model is it requires manually finding proper values for the number of compartments. In addition, it may require many differential equations to fit the data and may not adequately describe some complex features.

Delay differential equations (DDEs) provide an alternative way to model delayed outcomes that does not suffer these disadvantages. In this webinar, we introduced DDEs and demonstrated their relationship with traditional models such as transit compartment models, typical absorption models, and models for describing atypical absorption profiles. We also explained how DDEs are implemented in Phoenix NLME and demonstrated this new functionality with some examples.