1 reply to this topic

[Omamah]

Hi all,

I have data that I need to analyze

These data are blood samples that are collected sparsely over two visit of a drug that is given orally, the first visit is during the first two months of treatment and during these two months of treatment the drug is given orally once daily. The sampling was taken at three times points during the visit and one predose. Visit two, is during the second phase of treatment (from month 3 to 6) and during this period the drug will be given orally three times weekly. The sampling in visit two is also collected at three time points.

I have some questions and I really appreciate any help on that

So to calculate the elapsed time do I calculate the time from the first dose that was given or the last dose before sampling?

And in case it is the time when the last dose was given, how can I take into consideration, while modeling, the possible accumulation of the drug from the day the drug was started?

But in case I have to calculate the elapsed time from the first dose that was given, do the three time points that were taken on the same make a difference? And do I need to convert the day to hours?

 

Does phoenix calculate the time in the time format? Or do I have to convert it to some sort of numbers?

and how can do the modeling for the drug if it is given in two different intervals 

 

The second thing is:

Are three points enough for making a curve stripping? And how do I do the curve stripping if there is any guidance or reference about the algorithm of it, that will be so helpful.

How can I do the curve stripping based on the data that I have using the Phoenix?

and will i be able to calculate the Cmax and the Tmax 

 

 

any suggestion will be highly appreciated

 

 

thank you all

Omamah

Edited by Omamah, 01 December 2016 - 08:05 PM.

[Simon Davis]

Generally phoenix is looking to work with a derived time from dose, as opposed to a clock time.  You can use clock date times in the Phoenix model but in your case I'm not entirely sure it helps.

Whatever time unit you decide to work in, be consistent e.g all days or all hours etc.

 

I would suggest you calculate time from 1st dose, as I did in the project I sent you previously.

I will also repeat; curve stripping itself is only a means of getting inital estimates, you do not probably have enough data to do the curve stripping, you *may* be able to model that data to get Cmax and AUC etc.

 

I think if you want to get more help you need to post your data and protocol, to answer the questions I asked eg. is tau in the second phase 48 hours (every 2 days) or 56 hours, (3 times a week) etc. What exacly was the dosing regimen and when did it change.  Phoenix models can work with irregular dosing but you actually have to specify what that was either explicitly in a worksheet, or using the ADDL function as I showed you.

Perhaps if you built a work sheet when the different events occured you will be in a better position to formulate your questions, however with 3 time points and 5 subjects you sent previously it is going to be hard problem to fit with confidence.

 

 Simon.