enzyme turnover

Dear nmuser, I had analyzed data set of a CYP- inhibitor agent using NONMEM ADVAN 6. A two-comp. model was used to describe the parent and its metabolite data sets sid by side to a hypothetical enzyme compartment. All estimates are fine except the KENZ (enzyme turnover rate was about (2 hr-1) which is 100-fold the published value. my code is $DES C2=A(2)/V2 ; for parent C4=A(4)/V4 ; for metab DADT(1)= -KA*A(1) DADT(2)=KA*A(1) - CL24*A(3)*C2 DADT(3)= KENZ - KENZ*A(3) - KIRR *C2 *A(3) DADT(4)=CL24*A(3)*C2 - CL40*C4 If i use the Emax and IC50 mode, the result is similar. what is wrong with my code ? All suggesion are wellcome. Regards Khaled ____________________________________________________________________________________ Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ