Jump to content


Photo

How can I show dose-normalized parameters based on mg and not nmol/L?


  • Please log in to reply
5 replies to this topic

#1 JWellbourne

JWellbourne

    Newbie

  • Members
  • Pip
  • 3 posts

Posted 14 April 2023 - 02:03 PM

Hi All, relatively new user of Phoenix here with a question/ problem.

 

I have concentration time data that I want to do NCA on.

 

Lets say for example, I want to calculate AUC (h*nmol/L) and AUC/dose, but for dose, I don't want to use nmol/kg, I want to use mg/kg. So the units should be h*kg*nmol/L/mg. 
 

When I can calculate based on molar dose (h*kg*nmol/L/nmol) my NCA will be fine, but this is not the output I want. 

 

The problem is that when I do a dose normalization for mg/kg to get h*kg*nmol/L/mg, (which is easy using the dose options interface) other parameters are miscalculated and with the wrong units.

 

For example I want to calculate clearance with the units mL/min/kg. However when I do the dose normalization for mg to get the desired AUC/dose calculation and units, the units are forced to {mg/(h*nmol/L)kg}, giving an undesired calculation and output. 

So I can either set up my NCA so that I get the correct AUC/dose, or the correct clearance, but not both.

 

Perhaps I am doing something wrong, not sure. Any advice? 


  • Austingar likes this

#2 Simon Davis

Simon Davis

    Advanced Member

  • Administrators
  • 1,316 posts

Posted 14 April 2023 - 02:50 PM

Hi Joel, can you post a simple example project? and calrify what output units you want,  I'm not sure why you want to keep 'mixed' units?

 

Would it not make more sense to convert your conc your to mg or ng etc. if you want to normalise by mg dose levels?

 SImon.



#3 Linda Hughes

Linda Hughes

    Advanced Member

  • Members
  • PipPipPip
  • 73 posts

Posted 17 April 2023 - 01:04 PM

If concentration is in moles and dose is in grams, the NCA object will not be able to do any unit conversions for parameters with units that mix moles and grams because the NCA object does not allow specification of molecular weight.  NCA will have to use the default units for those parameters, and those units are built from the input data units and dosing units.


#4 JWellbourne

JWellbourne

    Newbie

  • Members
  • Pip
  • 3 posts

Posted 18 April 2023 - 08:19 AM

Hi Joel, can you post a simple example project? and calrify what output units you want,  I'm not sure why you want to keep 'mixed' units?

 

Would it not make more sense to convert your conc your to mg or ng etc. if you want to normalise by mg dose levels?

 SImon.

 

Hi Simon, 

I work in the drug discovery/ development field. In my case it makes sense to keep molar units for my concentrations, because data are entered with other compounds in a large database, and the compounds have widely different molecular weights. To compare actual drug exposure per molecule the units therefore must be molar.

It also makes sense for us to denote dose in mg/kg, as each drug's dose will be determined as such, especially once it enters clinic. Also, doses are usually tested in standardized intervals, even in the preclinical stage. So e.g. 0.1, 1, 3, 10  mg/kg etc.. Of course I can convert this, but the issue is that for easy and fast interpretation of data by project teams, and to contextualize results amongst others in the series, or to other series entirely, this is the standard denotation. 

And finally, even though I agree with this format in our specific case, I am not in a position to change it even if I wanted to, as this is the agreed upon standard in our relatively large organization.

I could make an example file if you wish, but I have been informed by several people now (and one other in this thread) that what I am asking is not possible. 

Alas, I guess it means manually editting my exported tables in excel to divide AUC by 0.1, 1, 3, etc... so not a big deal, but still, I was hoping for an easy way to configure the NCA so that it can do this simple calculation.

Thanks for your reply nevertheless! 



#5 Simon Davis

Simon Davis

    Advanced Member

  • Administrators
  • 1,316 posts

Posted 18 April 2023 - 08:22 AM

Perhaps you could enter dose amount in molar units but use a treatment label column as a Sort or Carry that has your mg/kg levels for summarizing in tables etc.



#6 JWellbourne

JWellbourne

    Newbie

  • Members
  • Pip
  • 3 posts

Posted 18 April 2023 - 08:23 AM

 

If concentration is in moles and dose is in grams, the NCA object will not be able to do any unit conversions for parameters with units that mix moles and grams because the NCA object does not allow specification of molecular weight.  NCA will have to use the default units for those parameters, and those units are built from the input data units and dosing units.

 

Thats unfortunate, considering how simple the operations would need to be, theoretically.

I could imaging having a separate value for mg/kg and nM/kg. Anyway the program can already do the conversion, why not store the variables in both formats?  Then you could call on one to calculate the parameters and one to dose normalize. Just my two cents. 






0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users