Analyzing Dissolution Test Data with SigmaPlot’s Excel Spreadsheet
An Excel worksheet, called the Dissolution Calculator, was created in SigmaPlot to simultaneously analyze dissolution test data and create a publication quality graph of the results. DiFeo and Shuster (1) published an Excel worksheet that computes basic statistics for replicate measurements of drug concentration vs. time. The SigmaPlot notebook Dissolution Calculator.jnb contains this Excel worksheet.
Download the file DissolutionCalculator.zip and double-click on it to obtain this notebook.
You may also download the custom curve fit library Release.zip to fit various equations to your dissolution data. You may fit either the mean values of the replicate data or, using the replicate data format, the replicate data itself.
Examples of SigmaPlot graphs produced by this worksheet are shown above. The graph on the left displays twelve superimposed plots of percent dissolution vs. time for each of the twelve dissolution vessels. The mean and standard error of this data is shown on the right graph.
The Excel worksheet was designed for a constant volume experiment. It corrects for the dilution caused by replacement of the sample volumes with fresh dissolution medium. It was also designed to satisfy FDA validation protocols. For example, the worksheet is protected from user modification except the cells for data entry.
Procedure for Using the Dissolution Calculator
Simply enter your data into the Excel worksheet. The formatted results and SigmaPlot graphs are created automatically. The Dissolution Calculator notebook contains the two objects shown below – the Excel Dissolution Calculator worksheet and the SigmaPlot graph page called “% Dissolution vs. Time Graphs”.
Double click on the Excel worksheet icon to open it. The data input portion of the worksheet is displayed.
Enter the sample times, standard HPLC responses, drug and experimental data and the 12 vessel by 6 sample time HPLC sample measurements. The % dissolved results are shown in the results portion of the worksheet.
The results expressed as percent dissolved are displayed in the upper array of cells. The mean values, standard deviations and relative standard deviations are displayed at the lower left. A small Excel preview graph is also included in the report.
Double clicking on the “% Dissolution vs Time Graphs” graph icon in the Dissolution Calculator notebook produces the following formatted publication quality graphs.
DiFeo, T.J. and Shuster, J.E. Validation of a computer spreadsheet used to perform dissolution calculations. Drug Development and Industrial Pharmacy, 22(12) (1996) 1187-1192.