$ABBR REPLACE Limitations?

Hi, I’m working in NONMEM 7.4.1 with a model where I need to track 4 drugs simultaneously. To increase the model quality, I’m making heavy use of $ABBR REPLACE to keep track of THETA, ETA, and CMT numbers. I traced an issue with my model where there was no gradient on a bioavailability term to the fact that this substitution didn’t seem to be working: $ABBR REPLACE FCMTD1GUT=F1 … $PK … FCMTD1GUT = THETA(1) FCMTD1GUT didn’t seem to be effectively replaced to F1, so the bioavailability parameters had no effect. When I changed it to just directly name F1, it worked as expected. $PK … F1 = THETA(1) It’s not obvious from the $ABBR REPLACE section of the manual that this is a limitation of $ABBR REPLACE. Is this an issue or am I missing something? Thanks, Bill ------------------------------ http://www.humanpredictions.com[image: Human Predictions Logo] http://www.humanpredictions.com/ http://www.humanpredictions.com*William S. Denney, PhD* Chief Scientist, Human Predictions LLC +1-617-899-8123 [email protected] This e-mail communication is confidential and is intended only for the individual(s) or entity named above and others who have been specifically authorized to receive it. If you are not the intended recipient, please do not read, copy, use or disclose the contents of this communication to others. Please notify the sender that you have received this e-mail in error by replying to the e-mail or by calling +1-617-899-8123. Please then delete the e-mail and any copies of it. Thank you.