Hi Marie, The message "PK PARAMETER FOR BIOAVAILABILITY FRACTION IS NEGATIVE" indicates the source of your issue, but it can be misleading as NONMEM can also report this error message if the bioavailability parameter is 0.
I would suggest that you look at the parameterization of your bioavailability parameter (F1, F2, etc...) and check if the value can be set to 0 or negative values (particularly if you have an IIV term on it)... Maybe share your full model code if you are not sure how to fix the issue. Sebastien Regeneron - Internal Regeneron - Internal ________________________________ From: [email protected] <[email protected]> on behalf of Marie Rajerison <[email protected]> Sent: Tuesday, March 11, 2025 9:39 AM To: [email protected] <[email protected]> Subject: [External] [NMusers] NONMEM and Bioavailability fraction Dear NM users I am running an extravascular pop PK model with dual absorption and got the following message from NM: Has anyone experienced the same issue and how to fix it? Thank you in advance for your help Marie Dear NM users I am running an extravascular pop PK model with dual absorption and got the following message from NM: [cid:[email protected]] Has anyone experienced the same issue and how to fix it? Thank you in advance for your help Marie ******************************************************************** This e-mail and any attachment hereto, is intended only for use by the addressee(s) named above and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail, any dissemination, distribution or copying of this email, or any attachment hereto, is strictly prohibited. If you receive this email in error please immediately notify me by return electronic mail and permanently delete this email and any attachment hereto, any copy of this e-mail and of any such attachment, and any printout thereof. Finally, please note that only authorized representatives of Regeneron Pharmaceuticals, Inc. have the power and authority to enter into business dealings with any third party. ********************************************************************
