This StarDrop script estimates free fraction (fᵤ) in microsomes, hepatocytes, and plasma even when some assays are missing, converting “% bound” to fᵤ and using a log-partition (logK) transform with MMV-derived linear fits.
It prioritises the best inputs (hepatocyte → Albimax/PPB → experimental logD → calculated logD), treats species consistently, and propagates uncertainty so each fᵤ includes an error estimate.
Practically, it lets you correct assay readouts and convert intrinsic clearance to unbound values (Clint/fᵤ), enabling cleaner cross-assay comparisons and faster decisions.
Version
This integration is available to use with the latest version of StarDrop (Windows and macOS). To find out which version you have installed, start StarDrop and select the Help->About menu.
If you are using an older version of StarDrop, please contact us at support@optibrium.com and we will be happy to help install this script on your StarDrop client.
Installing the script
Windows installation
To install on Windows:
- Download the user guide
- Download the script file
- Unzip the file and open the resulting folder in Windows Explorer
- Close StarDrop if necessary
- Double-click on the file load_script.bat to run the automatic installer. The batch file will copy all the relevant files to the correct locations.
– Note: in some cases, this action may require you to override a warning from the operating system. - Start StarDrop
- A new entry named Calculate fraction unbound will appear under the Custom Scripts menu in StarDrop
- Install the models as described in Section 2.4 of the User Guide.
macOS installation
To install on macOS:
- Download the user guide
- Download the script file
- Unzip the file and open the resulting folder in Finder
- Close StarDrop if necessary
- Copy the following files and folders, creating new folders as necessary:
– binding_calculation.py to /Users/<USERNAME>/StarDrop/py3/AMG
– fractioncalculator folder to /Users/<USERNAME>/StarDrop/site-packages - Start StarDrop
- A new entry named Calculate fraction unbound will appear under the Custom Scripts menu in StarDrop
- Install the models as described in Section 2.4 of the User Guide.
To run the script, open a suitable data set. Select Calculate fraction unbound under the Custom Scripts menu in StarDrop. The script will calculate predicted values for the fᵤ in hepatocytes (1 million cells/mL), microsomes (0.5mg/protein/mL), Plasma Protein Binding (PPB), or Albumax assays from other assay data, experimentally-determined logD, or calculated logD. For some calculations, results will be returned for neutral or basic compounds only. When you run the script, you will be prompted to choose which prediction you want to make. Select the value you would like to predict and click OK.
Please read the user guide for more information on how to use this script and for the complete list of available calculations.
Installation files
Windows installation
To install on Windows:
- Download the user guide
- Download the script file
- Unzip the file and open the resulting folder in Windows Explorer
- Close StarDrop if necessary
- Double-click on the file load_script.bat to run the automatic installer. The batch file will copy all the relevant files to the correct locations.
– Note: in some cases, this action may require you to override a warning from the operating system. - Start StarDrop
- A new entry named Calculate fraction unbound will appear under the Custom Scripts menu in StarDrop
- Install the models as described in Section 2.4 of the User Guide.
macOS installation
To install on macOS:
- Download the user guide
- Download the script file
- Unzip the file and open the resulting folder in Finder
- Close StarDrop if necessary
- Copy the following files and folders, creating new folders as necessary:
– binding_calculation.py to /Users/<USERNAME>/StarDrop/py3/AMG
– fractioncalculator folder to /Users/<USERNAME>/StarDrop/site-packages - Start StarDrop
- A new entry named Calculate fraction unbound will appear under the Custom Scripts menu in StarDrop
- Install the models as described in Section 2.4 of the User Guide.
How to use the script
To run the script, open a suitable data set. Select Calculate fraction unbound under the Custom Scripts menu in StarDrop. The script will calculate predicted values for the fᵤ in hepatocytes (1 million cells/mL), microsomes (0.5mg/protein/mL), Plasma Protein Binding (PPB), or Albumax assays from other assay data, experimentally-determined logD, or calculated logD. For some calculations, results will be returned for neutral or basic compounds only. When you run the script, you will be prompted to choose which prediction you want to make. Select the value you would like to predict and click OK.
Please read the user guide for more information on how to use this script and for the complete list of available calculations.