Release Notes — GastroPlus® X.2

GastroPlus® X.2 – 2025 Release Notes

August 28, 2025

Dear GastroPlus® User,

We are thrilled to share the latest enhancements to the GastroPlus® X (GPX™) platform. This 2025 release introduces innovative new functionality, key usability improvements, and targeted fixes that enhance model flexibility and workflow automation. Our commitment remains to empower your PBPK/PBBM modeling with cutting-edge tools grounded in established science.

Below, you'll find the major highlights from this year's development efforts.

New Modules

Subcutaneous and Intramuscular Dosage Routes

Simulate dosing through subcutaneous and intramuscular routes, including long-acting injectable formulations.

ACATPlus™

Enhanced oral absorption modeling, with the inclusion of gut lumen contents and mucus, the addition of mucosa, submucosa, and muscularis tissue layers, and support for all colon sections with subsection modeling.

AssessmentsPlus™

Compound and simulation assessments empower users to efficiently build high-quality PBPK/PBBM models using embedded expert knowledge.

Orchestrator

Automate GPX workflows through this local API, complete with R and Python packages and support.

P-PSD™

Fit in vitro USP2 dissolution data using a product particle size distribution, modeling the formulation-specific surface area of drug substance available for dissolution.

New Features

ACAT

Added default microbiome expression.

General

Added default NAT2 enzyme expression.
Added ability to calculate Diffusion Coefficient from Molecular Weight in Molecular Properties panel.
Permanently display the temperature corrected values in the Solubility Panel table.
Improved support for parallel processing in core calculations.
Streamlined handling of very large datasets within core engine routines.
Improved consistency of unit handling across modules.
Upgrade database to 10.2.0.

IVIVC

Improved graphical reporting and color differentiation of IVIVC outputs.

Lab Book

Added support for more detailed metadata when creating and storing simulation records.
Added ability to paste plots within GPX.
Streamlined Lab Book export process for easier archiving.

PBPK

Added support for user-defined PBPK tissues.
Added ability to remove PBPK tissues.
Added the Venous Junction compartment for accurate modeling of high distribution/high clearance compounds.
Added the Distribution Dashboard sub-panel, which enables detailed analysis of the contributions of individual tissue components to Kp calculations, the calculation of Ka_APL from measured tissue Kp values, and support for mechanistic Kp scaling through optimizable Kp modifiers.

Plotting

Added customizable units and axis controls to plot options.

Reporting

Added Quality Control Matrix (QC Matrix) output format.

Virtual Bioequivalence

Added support for Replicate Design studies.

Improvements and Bug Fixes

ACAT

Updated UGT2B7 relative expression in Ileum 1.
Corrected default expression values for enzymes and transporters with unknown expression in pre-clinical species.

Asset Export & Import

Simulations containing user-defined permeability correlations can now be properly exported.
Fixed issue where metabolite compounds were missing when importing by compound name.
Fixed an issue where incomplete or invalid export jobs were not flagged properly.
Improved compatibility of exports with downstream external tools.

DDI

Perpetrator Administration Interval and Steady State Concentration settings now save properly.
Synchronized colors for Metabolic Profile plots in Liver & Gut.
Fixed crash that occurred during dynamic DDI simulations.
Removed irrelevant warning messages in the DDI module.
Revised dose entries can now be properly updated under ‘Dosing’ in the DDI module.
Corrected perpetrator concentration calculations for steady-state DDI.
Fixed crash when exploring analysis results in dynamic DDI simulations.
Removed duplicated rows in 'Victim Metabolism Transport Details'.
Users can now properly delete rows in the Perpetration Parameters table.
Ensured variability in Pop Sim runs with only perpetration parameters selected.
Time-dependent inhibition now properly incorporates user-defined turnover rates.
Multiple inhibition types can now be entered reliably.
Fa, FDp, and F values from Observed Data are now correctly read.
Fixed save errors after changes in the DDI module.
Resolved issue where AUC0-t equaled AUC0-inf for command line dynamic DDI runs.
Corrected steady-state DDI predictions to match release version expectations.
Ka values for steady-state DDI are now read back from the database.
Added support for additional gut concentration predictions when selected.
Resolved missing metabolic profile visuals in Liver and Gut for dynamic DDI.
Fixed legend color selection for Key View plots in DDI simulations.
Victim-only metabolic profiles now show both gut and liver appropriately.
Perpetration variables are now available in Pop Sim DDI configurations.
DDI output files are now created automatically.

Dissolution

Updated default units for dissolution to prevent mismatched reporting.
Fixed issues where dissolution data handling was inconsistent across modules.
Improved reliability of dissolution simulations at very high doses.

General

Legacy database imports with metabolites now process correctly without data loss.
Resolved unresponsiveness in the Biorelevant In Vitro Solubilities panel.
Updated Key View plots for IV infusion dose types to reflect correct units.
Templates containing user-defined permeability correlations can now be used reliably, and these correlations now persist after reopening saved projects.
Prevented simulation runtime crashes for compounds with a very high molecular weight.
Fixed handling of tabulated particle size distributions.
Particle bin frequency calculation now produces correct results.
Projects can now be created in folders with Japanese characters.

GUI

Expand parameters names in PSA, Population Simulation, and Optimization runs.
Improved alignment of displayed columns in multiple simulation views for easier interpretation.
Enhanced responsiveness of interface elements within very large projects.
Refined graphical display of regional absorption and distribution profiles.
Resolved refresh issue in User Defined Permeability Correlation settings.
Updated display of log-linear functions in User Defined Permeability Correlation.
Improved usability and stability of the Run Control window.
Stomach Retention Time field now properly editable based on dose form.
Observed solubility selections are now saved as expected.
Added clearer tooltips and labels.
Fixed various typos.

IVIVC

Fixed compartmental deconvolution and bioavailability correlation functionality.
Deconvolution statistics now display correctly.
Optimization output in IVIVC is now properly generated.
Refined the initialize estimates function for greater stability.
Ka and Lag Time fields are now populated correctly.
Enhanced error handling for unsupported input conditions.

Lab Book

Deleted or renamed data profiles are now properly reflected, preventing stale references.
Fixed inconsistencies in metadata storage for saved simulation records.
Improved handling of profile renaming to avoid duplicate entries.
Improved handling of large numbers of saved Lab Book profiles for better performance.
Enhanced profile editing features to reduce errors during renaming or reorganization.

Metabolism & Transporter

Standardized and corrected expression level units.

Observed Data

Addressed issues with "UseDirectly" option in Particle Size Distribution.
Resolved refresh issues in particle size distribution inputs.
Improved log-normal fitting in particle size distribution.
Fixed incorrect Weibull plot when time units are in minutes.
Weibull parameters are now properly refreshed after optimization.
Dissolution data can now be pasted correctly on European-language machines without errors.

Optimization

Partition Coefficient (Kp) now refreshes correctly after update.
Fixed an issue where Km synchronization was not properly applied.
Optimization parameters are now shown with correct units.
Weibull optimization for therapeutic window fitting has been corrected.

PBPK

Fixed display of arterial and venous clearance when reopening projects.
Apical PStc values are now assigned appropriately for certain perfusion-limited tissues.
Enzyme parameters in systemic circulation can now be permuted in PSA and population simulations.
Pediatric transporter expression is now properly referenced in the expression source.
Enabled age settings for swine physiologies.
Lymphatic flow settings are now synchronized across relevant subpanels.
Fixed initialization behavior in the fetus gender dropdown.
Albumin ratio method changes in advanced settings are now correctly applied to Kp calculations.
PStc values now update correctly after copying a physiology.

PDPlus™

Users can now plot Effect vs Concentration even without simulated PD.

PKPlus™

Updated displayed name for AUMC units.

PSA

Total mass in PSA is now accurately reflected when combined with other parameters.
Particle density inputs are now available for PSA simulations.
Improved plot display for changes in key PK parameters in cross PSA.

Plotting

X-axis no longer resets when y-axis scale is changed.
Removed extraneous lines on Key View plots for certain simulations.
Improved visual stability of regional absorption plots, preventing column drift.
Improvements to axis controls, color schemes, and plot settings across Key View and Analysis View.
Added new default color schemes to improve clarity in overlapping curves.

Population Simulation

Fixed issues with Weibull-fitted dissolution data.
Non-American populations can now be selected for simulations.
Ensure subject generation produces valid distributions in all cases.
Addressed memory constraint errors during population simulations and virtual bioequivalence runs.
Saved population data is no longer overwritten after reruns.
Added option to combine outputs from multiple trials into a single Excel file.
Enable user-specified confidence intervals on population simulation plots.

Reporting

Experimental Cp column now populates correctly in WinNonLin format.
Removed exogenous entries from Excel outputs.
Correct dose form is now displayed for IV bolus in outputs in all cases.
Additional solvents and solubilizers are now included in outputs.
Report output toggle now deactivates table interactions consistently.
Controlled release parameters are now included in Excel outputs.
Added new options for dissolution output reporting to match updated regulatory guidelines.

Simulations

Duplicate output points in simulations have been removed.
Duplicated observed data in copied simulations is no longer present.
Simulation panel responsiveness has been significantly improved.
Simulation output folders are now created for simulations that have been created by ADMET Predictor.

Virtual Bioequivalence

Fed intersubject variability is now correctly applied.

Licensing

Switch to Reprise License Management system.

Installation & Support

System Requirements: Windows 10/11 (64-bit) or Windows Server 2022
Minimum RAM: 16 GB
Activation: Required via licensing@simulations-plus.com
Installation Guide: Included in the ZIP package from our ShareFile portal

Getting Help

For any assistance, enhancement ideas, or questions, please contact:

📧 support@simulations-plus.com
🌐 www.simulations-plus.com
📞 +1-661-723-7723

Thank you for your continued support of GastroPlus®. We remain committed to delivering innovation, accuracy, and excellence for your modeling and simulation needs.

Sincerely,

Simulations Plus, Inc.