HI, can someone clarify the syntax for inverse natural log in a textual model? example if I wanted to state that the change in mass is = Amt * e^-kat? I have a journal where the transit of drug to the Lymph space is written in derivative as: dAmtLymph/dt=ka * F *Amt * e(superscript: -ka * t)… thanks Elliot
That equation is correct only for single dose extravascular where kaAa has been replaced by the ka by the analytical solution for the amount in the extravascular compartment. Now, once you have more than one dose, then I believe you cannot use that equation as described. Then in general, it is just easier to write kaAa as the input rate into the central compartment. The model has the code to account for multiple dose as the integrator changes its initial conditions at each dosing time. If you have single extravascular dose, then you can write the code as follows: In your data set, define a column called Amt which has the dose you gave (single dose) for each patient and put it as the first record (no need to have it written at each record). Then, write the following code derive(AmtLymph=kaFAmtexp(-ka*t)) # t is the time, derive(AmtLymph means d(AmtLymph)/dt, exp means exponential covariate(Amt) Be careful that PML is case sensitive. The order where you put derive and covariate is not important Best Serge