4 replies to this topic

[Rajbharan Yadav]

Dear Experts,

Typically we write two sets of equation for simultaeous fitting of IV and PO data (1-compratment) in Phoenix. Can we do the fitting by writing a single equation for both the route (IV/PO) in simultaneous fitting in phoenix.

Looking forward to hear your comment,

Thanks

Raj

[serge guzy]

Dear Raj

I think that this code would work. It is based on the principle of superposition.

A demo project is attached. The idea is that we have an equation for IV and an equation for oral. The principle of superposition for linear kinetics allows us to add the 2 components. I used multiple dose to show that it should work also for multiple doses.

Let me know if it is helpful.

The template equation can be obtained by looking at model text for the 1c IV and then 1c Oral. You need to define A1frompo for the amount based on oral as you cannot use twice the same name and A1 is already used.

therefore you have

C = (A1+A1frompo) / V

 

Note that you can use graphical to emulate this combined route but then the program will shift to diff equations. Here it is going to use the analytical solution (closed form).

 

 

Best

Serge

 

test(){

    cfMicro(A1, Cl / V)

    dosepoint(A1)

    C1=A1/V

C1frompo=A1frompo/V

cfMicro(A1frompo, Cl / V, first = (Aa = Ka))

    dosepoint(Aa)

    C = (A1+A1frompo) / V

 

 

    error(CEps = 0.1)

    observe(CObs = C * (1 + CEps))

    stparm(V = tvV * exp(nV))

    stparm(Cl = tvCl * exp(nCl))

    fixef(tvV = c(, 50, ))

    fixef(tvCl = c(, 5, ))

 

 

 

    stparm(Ka = tvKa * exp(nKa))

fixef(tvKa = c(, 1, ))

 

    ranef(diag(nV, nCl, nKa) = c(0.1, 0.1, 0.1))

} [file name=one_equation_single_dose_IV_and_oral_official.phxproj size=1006662]http://pharsight.com/extranet/media/kunena/attachments/legacy/files/one_equation_single_dose_IV_and_oral_official.phxproj[/file]

Attached Files

•  one_equation_single_dose_IV_and_oral_official.phxproj   983.07KB   400 downloads

[Rajbharan Yadav]

Thanks Dr Suzy,

This is working fine. I am getting only IV outpout and fit and could not able to get PO fit. I am arranging Raw data in this format

time IV po dose_IV dose_po

0 2356 2356

0.5 950 75

1.5 746 150

3.5 502 350

5.5 150 125

7.5 75 45

 I want to get single dose IV and PO fit. _Please comment about arrangement of IV and PO data and single dose equation.

Thanks

Raj

[serge guzy]

Dear Raj

If a patient gets either both IV and PO , either just IV or PO, the response should show up only in one column, not 2 columns as you seem to show me.

Look at my format in the project I attached in my previous reply.

If the same patient got IV, then was washout and then got PO (cross over study), then the model should be constructed differently but it is still one response only. The response refers to the concentration of drug in Plasma.

Let me know what are the conditions of your experiment but you need definitively only one response column if you measure the concentration in Plasma only (I suppose so).

best

Serge

[Simon Davis]

Raj - I concur with Serge. If you can observe the conc resulting from IV and Oral as separate columns then they can't have occurred at the same time in the same patient; which is what I thought your original question was.

Can you explain *why* you want one equation to fit these two different experiments? (you followed the simultaneous fitting example in the NLME examples guide already right?

If you do want to put this data in one column you could use the stacker; but it's still going to identify the data by route e.g.

to give you these results;

(note it's much easier for us if you post and actual Phoenix project or at least CSV file that we can load up rather than having to extract data from a message, create a file and then load it up.)

It also shows us your current train of thought etc.

Simon

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