Modeling Drug Infusion

I’m developing a 2-compartment model in stan to analyze a pk dataset in which a 10 mg dose of a drug was administered into the central compartment as a 15 minute infusion. I want to include the ODEs as a function in the first block of the stan code. Could you possibly direct me to example code describing drug administration via a short infusion to guide model development? Thanks in advance for your help.

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This is not my area of models but here two threads discussing this kind of thing.

There is some discussion here for a one compartment Bounding posterior output of pharmacokinetic model that might get you going in the right direction.

Here as well: Stan simple model for pharmacokinetics

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You can, but you don’t have to add ODE function because 2-cpt model has analytical solution. All you need is to code that solution. This way is more efficient than numerical solution.

Shameless plug: you can also use Torsten, a pharmacometric library built on top of Stan as it has built in 2-cpt functionality. If you are comfortable with NONMEM model specification, Torsten could be your thing. If you still prefer numerical solution of ODE, check out this Torsten example for a possible implementation of 2-cpt model.


Is it really necessary to model it as an infusion? Often the infusion time is very short in comparison to when measurements are taken or what time-spans are of interest… unless you are really after mass balance and want to get things right just after infusion stops. In case you can simplify, then a bolus iv shot can approximate the infusion well enough.