Model building advice

From: "Eleveld, DJ" d.j.eleveld@anest.umcg.nl Subject: [NMusers] Model building advice Date: Wed, April 27, 2005 10:39 am Hello everyone, I am having difficulties getting a model to work with NONMEM and I hope someone can give me some advice. During simulation one model state variable must undergo step changes of various sizes at certain events. Between these events the same variable decays towards zero. I cant code the step changes as 'doses' directly in the input file because the size of the step change depends on the state of other variables in the simulation. When I try to code these step changes in DADT() portions of $DES there are endless problems with integration. My current best attempt uses COM variabels to force the step change but i get ERROR IN LSODI1: CODE 205 MESSAGE ISSUED FROM TABLE STEP even from simulation. I think being able to manipulate the A() values from within $DES would help, but NONMEM does not allow this. Another possibility would be to simulate a 'dose' to a compartment from within the $DES code but I dont know if this is possible. Does anyone have any advice as to how I can force step-like changes to a model state varaible in a way that NONMEMs integration routines can handle it? Thank you, Doug Eleveld