2 comp MM

From: R.Port@DKFZ-Heidelberg.DE (Ruediger Port) Subject: 2 comp MM Date: Fri, 11 Dec 1998 10:33:25 +0100 Hi everybody, a control file for a two-compartment model with MM elimination was posted a few days ago where the expression for the MM clearance in $DES is somewhat unusual in that VM, as it stands there, will have dimension concentration/time (e.g. (mg/L)/min) whereas it is usually understood to have dimension amount/time (e.g. mg/min). I thought if someone uses this code he or she should be aware of this distinction. The proposed control file has this code: S2=V1/1000 ;SCALING FACTOR FOR CENTRAL COMP $DES DADT(1)=-KA*A(1) DADT(2)=KA*A(1)-Q/V1*A(2)+Q/V2*A(3)-CL/V1*A(2)-VM*A(2)/(KM+A(2)/V1) DADT(3)=Q/V1*A(2)-Q/V2*A(3) By defining C2 = A(2)/V1 and C3 = A3/V2 one could rewrite DADT(2) like this: DADT(2) = KA*A(1) - Q1*C1 + Q2*C2 - CL*C1 - VM*A(2)/(KM + C2) The ratio A(2)/(KM + C2) in the last term on the right-hand side has dimension amount/(amount/volume), i.e. volume. If the entire term, VM*A(2)/(KM + C2), defines a change of amount per time, VM must have dimension (amount/time)/volume, or concentration/time. The following modification will produce a VM parameter having dimension amount/time (e.g. mg/min): DADT(2) = KA*A(1) - Q1*C1 + Q2*C2 - CL*C1 - VM*C2/(KM + C2) Ruedi ------------------------------------------------------------------------------ R.E. Port, Dept. 0420, German Cancer Research Center P.O. Box 10 19 49, D-69009 Heidelberg phone: x49-6221 42-3385 -3347 fax: -3382 e-mail: r.port@dkfz-heidelberg.de