Hi Monsumee,

You can try CompuSyn software. It's much easier to determine IC50 by entering the data quickly and effectively. CompuSyn software can be free downloaded. You can follow this way:

1. Click New Experiment; 2. Click New Single Drug; 3. Inputs Full name of the drug, Abbrev of the drug, and Units (e.g., nM); 4. Enter the first  set of Dose+Effect values. For example, Dose=20, Effect=0.30 (which means 30% of cells killed); 5. Press ENTER on your keyboard, then you can see the data are input and saved; 6. Type next set of Dose/Effect data, then press ENTER; 7. Repeat this process until all dose-response values are input and saved; 8. Press Finished; 9. Press Calculate Parameters, and the IC50 value is calculated and shown in the bottom. The software by default regards it as IC50, you can also calculate IC75 by entering 0.75 into the upper blank. 

Hope it would help you.

Jennifer

Hi 

Calculating IC 50 is very simple. All you need is to feed the data what you have obtained from your experiment using GraphPAd Prism software and use the non-linear regression analysis program in the software to generate your curve and IC 50 value.

Please follow the link- https://graphpad.com/support/faq/how-to-determine-an-icsub50sub/

Convert your concentration values to log10 and plot on X-axis and your % inhibition on Y-axis using Graphpad Prism. And then use the non-linear regression analysis function in the ANALYSE function. The above website link is a GraphPAD tutorial page and gives you the step by step protocol.

I hope this will be helpful.

Best,

s

Thanks Shubhankar Das ..  i will follow your suggestions

Hi Monsumee,

You can try CompuSyn software. It's much easier to determine IC50 by entering the data quickly and effectively. CompuSyn software can be free downloaded. You can follow this way:

1. Click New Experiment; 2. Click New Single Drug; 3. Inputs Full name of the drug, Abbrev of the drug, and Units (e.g., nM); 4. Enter the first  set of Dose+Effect values. For example, Dose=20, Effect=0.30 (which means 30% of cells killed); 5. Press ENTER on your keyboard, then you can see the data are input and saved; 6. Type next set of Dose/Effect data, then press ENTER; 7. Repeat this process until all dose-response values are input and saved; 8. Press Finished; 9. Press Calculate Parameters, and the IC50 value is calculated and shown in the bottom. The software by default regards it as IC50, you can also calculate IC75 by entering 0.75 into the upper blank. 

Hope it would help you.

Jennifer

 Thank you Han Zhan , i will try it out.

Hi Monsumee,

I am not sure what your question is. But if your question means what I think it is, then the answer is like this: -

1. After you have entered your data on inhibition % and concentration in excel sheet (in adjacent columns), then plot your graph with a scatter diagram. You will find the tap for it at the top of your excel sheet.

2. Then, press the layout tab. There, you click on Trendline. From the drop down menu, click on "more trendline options".

3. Set your trendline to "linear", "automatic", check the box  "intercept = 0" and "display equation on chart".

4. You will get a linear curve on your graph with an equation "y = m x". m is the slope which will have a numerical value.

5. Using the equation you got, you can calculate IC50.

6. Click on any cell of your excel sheet where you want to display your IC50 value. There, you type "=(50/m)", where m is the numerical value displayed on the equation of your graph, and hit enter. There, you will see your IC50 value.

I hope this answers your question.

You can also try by not checking the box "intercept = 0". You will get a different equation "y = m x + (or) - c, where c will be another numerical value which is your intercept value. Then you can calculate your IC50 value in the same way e.g. "=(50+or-c)/m"

I have described as per excel sheet 2007 version.

Thanks Debulman Syiemiong

How to calculate IC50

To calculate IC50, you would need a series of dose-response data (e.g., drug concentrations x1, x2, ...,xn and growth inhibition y1, y2, ...,yn). The values of y are in the range of 0-1.

Linear Regression

The simplest estimate of IC50 is to plot x-y and fit the data with a straight line (linear regression). IC50 value is then estimated using the fitted line, i.e.,

Y = a * X + b,IC50 = (0.5 - b)/a.

Log transformation

Frequently, linear regression is not a good fit to dose-response data. The response-curve fits better to a straight line if the x-axis is logarithm-transformed.

Excel add-in

ED50V10 (Readme) is an Excel add-in for calculating IC50/EC50 values. Input your data in the left columns, and your results will be shown in the right half of the Excel table.

To calculate IC50, input 50 in the "INTERPOLATE..." table (highlighted in blue), the result will be shown on the right (highlighted in green).

For log-transformation, go to Data Transformation on the upper-right, input 3 in the DOSE (X-axis)/1st cell.

Four-Parameter Logistic Function

Four-parameter (A, B, C, D) logistic function (or Sigmoidal)

is frequently used to fit dose-response curves. The drug data x is in logarithmic form. This is a standard function in most statistics software. The parameter C is the estimate of IC50 or EC50.

http://www.sciencegateway.org/protocols/cellbio/drug/hcic50.htm