Hello,
I need a help with IC50 determination in Excel. Usually I am doing it in sigmaplot or GraphPad usin four-parametr nonlinear regression, but now I must do it it Excel. I have seen some videos but I am not sure how to do it. Do you have any idea please?:)
Thank you!
Standa D.
With microsoft Exel with "Solver function", one may calculate nonlinear fitting and obtain IC50 or EC50 values. For example, Nat Protoc. 2010 Feb;5(2):267-81. doi: 10.1038/nprot.2009.182. Epub 2010 Jan 28.
Hello
Try with SigmaPlot or GraphPad prims it is easy to use . However you can check your calculated values online here:
http://www.changbioscience.com/stat/ec50.html
Beware of using a linear trendline, if your inhibition profile is not linear this will give you messed up values. I think you need more high and low concentration points on your graph, so you encompass no inhibition all the way through to full inhibition, 3 points for each is what I aim for to get a good curve for robust IC50 calculation.
See links here , hope help you
Good Luck
http://www.sciencegateway.org/protocols/cellbio/drug/hcic50.htm
http://www.sigmaplot.co.uk/splot/products/sigmaplot/productuses/prod-uses43.php
https://ar.scribd.com/doc/9473396/Excel-2007-for-Scientists
With microsoft Exel with "Solver function", one may calculate nonlinear fitting and obtain IC50 or EC50 values. For example, Nat Protoc. 2010 Feb;5(2):267-81. doi: 10.1038/nprot.2009.182. Epub 2010 Jan 28.
Why *must* you use Excel for determining IC50? In my view, Excel is extremely horrible tool for data analysis.
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I use Python with Numpy (math) and Matplotlib (plotting) for data analysis and visualization.
Hi Stanislav,
You can follow the protocol described in the nature Protocol paper mentioned above by Sheng-Nan. I f you can't download it please write back and I'll send you a copy.
The Solver functionality in Excel is able to fit functions with up to 6 (or more) parameters, so the four-parameter logistic (sigmoid) you need should go fine. You can find many examples on the internet. For example: http://www.excelmasterseries.com/ClickBank/Thank_You_New_Manual_Order/ePUB_Files/Advanced_Regression/Text/Nonlinear_Regression.html or http://people.chem.ucsb.edu/laverman/leroy/Chem116/PDF116CL/Solver.pdf and many more.
Best, Karoly
Thanks all!!!
@Martin Klvana I have to identify not classic IC50 which is assessed based on top and bottom plateaus e.g. (drug inhibits cell growth maximally to 20% of viability so the model on graphpad calculate 50% between 100 and 20%). I need to determine the real value which represents 50% inhibition of cell viability between 0% (blank) and 100% (control). Thanks ;)
Stanislav: I still do not understand your "now I must do it in Excel".
Stanislav, Martin is right, your comment does not justify the use of Excel. I have never done nonlinear regression in Excel and do hope I will never done it. Excel is not for that. You have used Prism from GraphPad, which is just a perfect tool for that. What you mentioned to be "not classic IC50" - in my opinion - sounds as a misunderstanding. You can tell Prism to estimate the IC50 assuming complete inhibition from 0% to100%. You just have to fix the maximal inhibition value as being not variable. Please refer to Prism manual.
Best, Karoly
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