Help on rounding error ( error=134) !

From: PING CHEN chen.1016@osu.edu Subject: [NMusers] Help on rounding error ( error=134) ! Date: Sun, 12 Nov 2006 17:24:52 -0500 Hi, I was trying to do the popPK for a unstable drug which will be converted into its metabolite quickly. We only measure the parent compound concentration which was far below the dose. For example, 120 umol was given as i.v infusion for 1 h but the plasma concentration of the parent compound is only around 0.02-1.5 uM. I just tried the simple ADVAN3 TRANS4 as follows, however, the result turns out to be a very large V2 and very small CL and keeping giving the rounding error ( error=134)! Does anyone can help me figure it out? $PK V1=THETA(1)*EXP(ETA(1)) V2=THETA(2)*EXP(ETA(2)) CL=THETA(3)*EXP(ETA(3)) Q=THETA(4)*EXP(ETA(4)) K=CL/V1 K12=Q/V1 K21=Q/V2 S1=V1 $ERROR IPRED=F W=F IRES=DV-IPRED IWRES=IRES/W Y= IPRED+W*EPS(1) $OMEGA 0.25 $OMEGA 0.5 $OMEGA 0.5 $OMEGA 0.5 $SIGMA 0.25 Thanks a lot. Ping