Chromatography Forum

Dear All,

Is there any one who is using the Regression and Confidence interval for the calculation of shelf life of drugs.

If anyone has any excel sheet prepared for this plsease share.

Regards

I have just prepared an excel sheet for estimation of shelf life based on regression and confidence interval. I have prepared the excel sheet with assumption that data is poolable.

Actually the test for equality of slopes and intercept (using ANCOVA) is difficult to do in excel and needs effort (atleast for me; may be this is subjective). So advanced software are better for this Job. Higher languages like R, S++, SAS, Matlab are better for these kinds of job. FDA provides a SAS macro program for shelf life estimation (STAB) (FDA SAS Drug Formulation Stability Program).

http://www.fda.gov/CDER/sas/index.htm

I don't think that forum provids option for attaching the files. So if you give me your mail ID, I will mail you the excel sheet. This file is based on confidence intervals rather prediction intervals that may be required in certain cases.

Dear Madan

Thanks for ur reply. U can forward me the excel file at my mail id

sandeepjcs@yahoo.com.

Thanks in advance.

Regards

So what do you do with this? Putting a label on pill boxes?

*ahem* That's tablet bottles

finished dosage form expiration dating - frequent Arrhenius plot application

So what do you do with this? Putting a label on pill boxes?

Dear Mueller,

What do you mean, i could not understand?

DR, sorry, but from my former replies you probably surmise that I am getting so jittery (who knows whats in the pills besides the main poison) that these things all look like pill boxes to me.

Sunjay, the translation by DR should help?

I have just prepared an excel sheet for estimation of shelf life based on regression and confidence interval. I have prepared the excel sheet with assumption that data is poolable.

Actually the test for equality of slopes and intercept (using ANCOVA) is difficult to do in excel and needs effort (atleast for me; may be this is subjective). So advanced software are better for this Job. Higher languages like R, S++, SAS, Matlab are better for these kinds of job. FDA provides a SAS macro program for shelf life estimation (STAB) (FDA SAS Drug Formulation Stability Program).

http://www.fda.gov/CDER/sas/index.htm

I don't think that forum provids option for attaching the files. So if you give me your mail ID, I will mail you the excel sheet. This file is based on confidence intervals rather prediction intervals that may be required in certain cases.

If you can let me know what you want, I can make it in R (opensource software) if you want.
Or I can adjust the excel file, just let me know what your requirements are.

Bart

If you can let me know what you want, I can make it in R (opensource software) if you want.
Or I can adjust the excel file, just let me know what your requirements are.

Hi Bart
Thanks for extending help

Suppose I have a degradation profile of a substance over a time at some fixed environmental conditions (in triplicates).

Aim is to construct three least square lines (for each replicate) such that slope is common for all. or in other words minimize residual sum of square of all three lines while keeping slope common.

Though I work with R-language sometime (premade programs never self written)but it would be good if same can be done in excel.

Can you e-mail me a (fictive) studie, so I know what kind of data should be in, how the input is, and I will give it a shot to adjust it to your needs.

You can reach me at bartjoosen_at_hotmail.com.

Bart