Modeling a concentration curve with secondary peaks?

Xiaoli, Try a dual absorption compartment model e.g. with ADVAN6. Here is a 1comp with 2 absorption comps: $MODEL COMP = (ABS1) COMP = (ABS2) COMP = (CENTRAL) ....... $DES DADT(1) = -K13*A(1) DADT(2) = -K23*A(2) DADT(3) = K13*A(1) + K23*A(2) - KE*A(3) Give a full dose to each absorption compartment, estimate F1 and code F2 as: F2 = 1 - F1 You can then estimate lag/abs rate constants/transit model parameters for each absorption comp to catch the doubles. Hope this helps, Joe At 13:55 26/10/2007, Hou, Xiaoli Shirley (Shirley) wrote: >I need help for modeling a concentration curve with secondary peaks. What >models could I use? I tried two compartment models, but it couldn’t capture >the secondary peaks. Suggestions or recommendations are highly appreciated. > >Thanks. > >Dr. Xiaoli Shirley Hou >Senior Biometrician, Biometrics Research >Merck Research Labs WP53-120 >West Point PA 19486 >Phone (215) 652-7498 (first week of each month) >Phone (540) 381-9599 (rest of time) >Fax (215) 993-1835 > > > >------------------------------------------------------------------------------ >Notice: This e-mail message, together with any attachments, contains >information of Merck & Co., Inc. (One Merck Drive, Whitehouse Station, >New Jersey, USA 08889), and/or its affiliates (which may be known >outside the United States as Merck Frosst, Merck Sharp & Dohme or MSD >and in Japan, as Banyu - direct contact information for affiliates is >available at http://www.merck.com/contact/contacts.html) that may be >confidential, proprietary copyrighted and/or legally privileged. It is >intended solely for the use of the individual or entity named on this >message. If you are not the intended recipient, and have received this >message in error, please notify us immediately by reply e-mail and then >delete it from your system. > >

With a linear model such as this one, you can also use ADVAN7 (or ADVAN5). These are likely to give more stable numerical results than can be obtained by integrating differential equations. Omit the $DES block. The names given to the rate constants define the connections between the compartments, e.g., $PK K13= ... K23=... K30=.... On Fri, 26 Oct 2007 15:14:26 +0100, "Joseph Standing" <[EMAIL PROTECTED]> said: > Xiaoli, > > Try a dual absorption compartment model e.g. with ADVAN6. Here is a > 1comp with 2 absorption comps: > > $MODEL > > COMP = (ABS1) > COMP = (ABS2) > COMP = (CENTRAL) > > ....... > > $DES > > DADT(1) = -K13*A(1) > DADT(2) = -K23*A(2) > DADT(3) = K13*A(1) + K23*A(2) - KE*A(3) > > Give a full dose to each absorption compartment, estimate F1 and code F2 > as: > > F2 = 1 - F1 > > You can then estimate lag/abs rate constants/transit model parameters for > each absorption comp to catch the doubles. > > Hope this helps, > > Joe > > > At 13:55 26/10/2007, Hou, Xiaoli Shirley (Shirley) wrote: > >I need help for modeling a concentration curve with secondary peaks. What > >models could I use? I tried two compartment models, but it couldn’t capture > >the secondary peaks. Suggestions or recommendations are highly appreciated. > > > >Thanks. > > > >Dr. Xiaoli Shirley Hou > >Senior Biometrician, Biometrics Research > >Merck Research Labs WP53-120 > >West Point PA 19486 > >Phone (215) 652-7498 (first week of each month) > >Phone (540) 381-9599 (rest of time) > >Fax (215) 993-1835 > > > > > > > >------------------------------------------------------------------------------ > >Notice: This e-mail message, together with any attachments, contains > >information of Merck & Co., Inc. (One Merck Drive, Whitehouse Station, > >New Jersey, USA 08889), and/or its affiliates (which may be known > >outside the United States as Merck Frosst, Merck Sharp & Dohme or MSD > >and in Japan, as Banyu - direct contact information for affiliates is > >available at http://www.merck.com/contact/contacts.html) that may be > >confidential, proprietary copyrighted and/or legally privileged. It is > >intended solely for the use of the individual or entity named on this > >message. If you are not the intended recipient, and have received this > >message in error, please notify us immediately by reply e-mail and then > >delete it from your system. > > > >------------------------------------------------------------------------------ -- Alison Boeckmann [EMAIL PROTECTED]