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Hello,

I am running a 2-compartment linear model, when I don't click closed form to use differential equations, the model is not converging with error message:

Initial parameter values result in -LL = NaN

Hi,

My colleagues and I were having a discussion on calculations regarding the omega and omegastderr output and getting this into useful terms that can help you better understand the variability for the purposes of reporting. We are hoping experts in the extranet community could help to clarify.

I know that the output on the omega block generates a variance.

For proportional/exponential error models

CV=sqrt(omega)*100

For additive error models

SD=sqrt(omega)

Are these conventions correct dependent the error model structure you select?

For the omegastderr, how does this term relate to the final parameter estimate? What math is involved to get this into an %RSE term?

To our understanding, for a given parameter

%RSE=(Omegastderr)/SQRT(Omega)*100

Is this correct? From what I can tell this is different than the calculation that is done with NONMEM output. Any insight would be greatly appreciated.

Lance

Hello, I am working on a model, and I need to test the model with plasma concentration to be log-transformed.

Is there an option in the software to transform drug exposure data from normal scale to log scale, or should it be done first before uploading the dataset?

Also, How can I transform estimated PK parameters back to normal scale after the analysis using the software?

Hello,

I am working on an indirect response model (limited inhibition of Kin), I have baseline values for each subject measured at the start of study. I need to use these values and fix them as E0 where E0 = Kin/Kout so that I can only estimate either Kin or Kout but not both at the same time.

I think there is a way to have these baseline values in a separate column in dataset and set them as covariate in the model code text. Can someone please help me with an example PML code that I can use to accomplish this? 

For dataset, do I add these at each timepoint for each individual as I would for other covariates or only at time=0 where they are actually measured?

If my thinking of approaching this is off, how can I take care of this? I don't want to fix E0 to a single value without implementing the interindividual variability observed with baseline measurements. 

Thanks a lot

Hello, I have a question about communicating the covariate impact to people who are unfamiliar with the Nonlinear mixed effect methodology used in PopPk analysis.

So, suppose we have body weight influencing drug (X) clearance, and an increase in body weight is associated with a decrease in CL, with the impact estimated by the model (- 0.5).

Can we say that increasing body weight by 10 kg intervals results in a 5% reduction in drug clearance?

Thanks     

Hi all, 

1. What method does Phoenix use to assess significance of covariate relationships with PK parameters in pop PK model?

2. After I add a binary categorical covariate to the model. In the result tab, I can get a boxplot of "eta with cov" and "str with cov". What method did Phoenix to generate those plots and  Can I use those plots to assess the signification of correlation?

Thanks,

Linda

Greetings,

Hi, 

How can I change time format "10/Dec/2014" to"10/12/2014"? 

I tried to use data wizard "datevalue" function, but to read it back to "dd/mm/yy" format. Thanks! 

I thought it would be useful to put a few comments explaining what you should see in this new forum and how to use it. 

First off you should see better search within the forum as well as indexing by Google and other search engines.

One of the big improvements is the option to get instantaneous notifications of new posts or if you prefer daily or weekly 'digests'.  However to obtain these you have to ‘follow’ the forum(s) of interest. 

To this end we have reduced the number of categories make this easier to follow your interests;

Phoenix WinNonlin Basics - to discuss NCA, data tools, tables, templates, also Reporter

Modelling & Simulation - using the Phoenix engine in both population and individual problems

Advanced Phoenix features - this is aimed to help with primarily CONNECT functions i.e. configurations and interoperability so IT/power users who configure larger workflows using third party tools (i.e. R, PSN, NONMEM) or exchange data with other groups i.e. CDISC, PKS, AP, etc.

IVIVC applying this tool to guide formulation development, biowaivers etc.

QT+  performing rapid comprehensive analysis of ECG interval data from clinical trials, SimCYP’s Cardiac Safety Simulator etc

Lastly, during migration we may have lost some formatting or links to attachments - if you have a problem with an old post please let me know e.g. by Reporting the post and I'll try and get that information re-linked.

     Simon

PS feel free to ask other forum usage questions here.

Hi,

If I have a phxproj file for a pop PK model fitting. How can I use RsNLME to simulate 100 virtual patients based on fitted pop PK parameters?

Thanks,

Linda

Hi Experts,

Could you please give me some suggestions about my mistake when running modeling?

why is the %CV so high in the Theta sheet? 

Appreciate your help!

Drug administration by IV and dosage is 0.9mg/kg. Cmax=19ug/mL.

Lead users at each company should already have received this notification last month and reminder yesterday with Draft Release notes so check you junk folders if you have not seen this please.  If you want to be added to that distribution list then please contact me.

We will give a general session for all existing users to discuss these new features on Thursday at 10 am EST, the session will last no more than an hour and will be recorded.  You may register below.

https://certara.zoom...qQVO7EChtLx2Wnw

With the next release of Integral 23.10.1, Certara will release a new feature for its industry-leading data repository that will support data storage requirements where 21 CFR (Code of Federal Regulations) Part 11 signature compliance is not necessary. The feature will allow specifically licensed Integral users to interact with designated folder structures without needing to securely sign for every interaction.  This feature will be available to both fully licensed users and partners, and the feature will work in the same repository where eSignature can still be required for 21 CFR Part 11 clinical studies.

For our users to preview this,  on Friday, 13th October, we propose to upgrade www.integral-staging.certara.com/ to the 23.10.1 release candidate, please anticipate a short down time from 11a.m EDT when the repository will be unavailable.

User action will be required: 

Complete and save work, and logout before 11 am (EST)

The Phoenix Integral 23.10.1 plug-in (or Integral Client 23.10.1) will be required and we will distribute the download links shortly.
Be sure to use the most recent versions of Phoenix 8.2.2, or 8.3.4, 8.3.5 or 8.4 with 23.10.1, prior versions are not tested or supported with this version of Integral. 

Thanks, Simon DAVIS

Senior Manager, Support

Can we explore the impact of introducing correlations between random effects in PK/PD modeling on the accuracy of predictions and the understanding of complex drug disposition mechanisms?

Hello,

I am attempting to save relevant modeling plots as vector images. I have tried a couple of things without success

1. Print PDF (does not show up as vector image)

2. Export as JP or PNG (these are not vector files)

3. Copy high resolution image and paste to word document - this does produce a vector image but it is cut off (see file attachment).

Anyone else encounter this issue? Trying to fix this instead of using a third-party licensed program to convert the non-vector output into vector

Hi 

I am working on a multi-compartment model and I have been using the two-way micro-parameter formulation with a K_in and K_out.

Ideally I would like to formulate the model where I can fit a Volume, K_in and K_out. That does not seem possible out the box it seems. I know there is the Cl/V fitting where you can check a two way clearance but I do like the explicit K values in both directions. 

I have two questions

1) is there a way to recover the volume value from the two-way microparameter setup?

2) is there a way to change my parameters to be mixed say Volume and K_in or something along those lines 

Thanks in advance 

Dear all,

For a popPK model I am working on, I estimated interoccasion variability (IOV) for CL for 4 different occasions, assuming the IOV estimates to be the same for all 4 occasions due to limited data availability. Therefore, I obtained 4 identical omega estimates and 4 identical standard error estimates for the four occasions (i.e. IOV on CL for occasion 1 =  IOV on CL for occasion 2 = IOV on CL for occasion 3 = IOV on CL for occasion 4). My understanding is that I only need to report one estimate and its standard error for IOV on CL as my model output, instead of reporting the same set of values 4 times defined by the occasions. However, I do not know what to report for the shrinkage associated with IOV on CL. In the Omega sheet, 4 different shrinkage values were shown associated with the 4 occasions, ranging from 0.3 to 0.9. From looking at published studies, people report only one shrinkage value for each IOV tested. How can I obtain an overall shrinkage value to report for the IOV on CL? The number of data points for each occasion are different (e.g. intense sampling on occasion 1 and 4, sparse sampling on occasion 2 and 3), in case this matters.

Thank you for your help!