Simulation with covariates

Dear NONMEM User Having done a simple 2 compartment model containing variability on CL and V2 explained by a continoues covariate (BW) and a categorical covariate (DRUG) variable like: TVCL = THETA(1)*BW+THETA(2) IF (DRUG.EQ.0) TVV2=TVV2*THETA(3) IF (DRUG.EQ.1) TVV2=TVV2*THETA(4) I then wish to do a simulation using ONLYSIM SUBPROBLEMS=1000 My question is how do I set up NONMEM to do a random selection of the covariates during the simulation? Say that I want to pick values of BW between 10 and 100 by random and DRUG equal 0 or 1? Thanks in advance Kim ________________________________ Kim Kristensen, M.Sc(pharm),Ph.D. Pharmacokineticist, Clinical Pharmacology Medical Science Sweden AstraZeneca R&D Lund SE-221 87 Lund, Sweden ________________________________