calculation of time-to-nadir

From: "Anthe Zandvliet" Apaza@SLZ.NL Subject: [NMusers] calculation of time-to-nadir Date: Thu, July 29, 2004 8:46 am Dear NM Users, I would like to calculate the time-to-nadir for a continuous variable for individual patients (time at which IPRED is minimal). Does anyone know if this is possible with nonmem and which code should be used for this purpose? I have tried the following code, but this didn't work, because: - in the $PK block DADT(1) and T are not recognized - in the $DES block DOWHILE statements are not allowed - in the $ERROR block T is not recognized (nor is DADT(1), but this can be redefined) IF(ICALL.EQ.4) THEN DOWHILE(DADT(1).EQ.0) CALL SIMETA(ETA) TMIN=T*EXP(ETA(1)) ENDDO ENDIF $OMEGA 0 FIX In the archive of the usersnet, I have found the following statement by Lewis Sheiner about calculation of Cmax, which made me think that it may not be possible at all to calculate the time-to nadir. "Some very simple models, such as the 1 compartment elimination with first order absorption, can be solved explicitly for Cmax as a function of whatever parameterization you are using. In such a case it is simple to reparameterize with Cmax as a parameter and one of the previous parameters, e.g., V, solved in terms of it and the other parameters. Where there is no explicit solution for Cmax (most cases), it will be harder.There is no problem finding Cmax: just simulate your model on a fine time grid and "read off" the value." File Name:99oct241996.html Subject: Deriving Cmax and the corresponding variability Posting: October 24, 1996 Thank you in advance for your suggestions! Anthe