Simulations Plus


Leading the modeling & simulation revolution...

What is GastroPlus™? 

GastroPlus is a mechanistically based simulation software package that simulates intravenous, oral, oral cavity, ocular, intranasal, and pulmonary absorption, pharmacokinetics, and pharmacodynamics in human and animals. Since 1997, Simulations Plus has evolved the ACAT™ (Advanced Compartmental Absorption and Transit) model to a high state of refinement, providing the industry's most accurate, flexible, and powerful simulation program. This smoothly integrated platform combines a user-friendly interface with sophisticated science to help you make better project decisions... faster!

GastroPlus is, by far, the most commonly used software of its kind. This includes all of the top 20 pharmaceutical companies, along with companies based in India, China, Brazil and more! It has been identified as the #1-ranked program for in vitro-in vivo extrapolation (IVIVE) and PBPK modeling, and has been the focus of several recent publications from the FDA!

See how our clients are using GastroPlus by reviewing the peer-reviewed publication list!

How is it being applied?

  • Rapid analysis and understanding of the behavior of drug candidates in animals and human
  • Understand food effects
  • Assess effects of influx and efflux transporters in gut or any tissue
  • Predict first-in-human/animal doses through PBPK modeling
  • Conduct virtual population studies - with expanded statistical reporting!
  • Fit complex nonlinear metabolism and transport in any tissue
  • Build PBPK/PD models with target tissue concentrations
  • Track multiple metabolites (and metabolites of metabolites)
  • Assist with Quality by Design (QbD) implementation
  • Deconvolute in vivo dissolution for IVIVC to guide formulation development and dissolution method design activities
  • Predict steady-state and dynamic drug-drug interactions (DDI) - includes metabolic- and transporter-based interactions & induction 
  • ... and more!
The GastroPlus simulations include:
  • NEW! Mechanistic model for in vivo precipitation - based on nucleation kinetics!
  • NEW! Infant & pediatric PBPK modeling - simulate for infants as young as 16 weeks premature, with automatic scaling of physiological parameters
  • Paracellular absorption
  • Drug-Drug Interactions (with optional DDI Module) - now both metabolic- and transporter-based interactions!
  • Models for predicting drug administration through ocular or pulmonary routes (with optional Additional Dosage Routes Module)
  • Population Simulator™ - predict likely population distributions of PBPK/PD results over different populations
  • Physiological models for human (fasted and fed), beagle dog (fasted and fed), rat (fasted and fed), mouse (fasted and fed), and cynomolgus monkey (fasted and fed), rhesus monkey (fasted and fed), rabbit, and cat
  • Variety of dosage forms: intravenous (bolus or infusion), immediate release (tablet, capsule, suspension, solution, lingual spray, and sublingual tablet), and controlled release (gastric retention, dispersed release, integral tablet, enteric coated tablet and capsule, and buccal patch)
  • Peff converter to convert user-measured permeability to human in vivo Peff
  • pH-dependent solubility and logD models
  • Options for defining pH-dependent dissolution and precipitation rates
  • Mechanistic effect of bile salts on in vivo drug solubility and dissolution
  • Enhanced treatment of nanoparticle effects on solubility and dissolution
  • Dissolution and precipitation dependence on particle size, shape and particle density
  • Chemical degradation of drug in intestinal lumen prior to absorption
  • Enterohepatic circulation
  • Parameter Sensitivity Analysis - quickly test sensitivity of results to changes in any model parameters
  • Metabolite tracking - easily link the formation of metabolites with the metabolism of parent(s) in a single simulation (with optional Metabolism and Transporter Module)
  • Ability to fit one-, two-, or three-compartment conventional pharmacokinetic models to IV and/or oral data (with optional PKPlus™ Module)
  • Physiologically based pharmacokinetics (with optional PBPKPlus™ Module)
  • Automated model fitting for single or multiple data sets (with optional Optimization Module)
  • Saturable metabolism and active transport in gut or other tissues and metabolite tracking (with optional Metabolism and Transporter Module)
  • NEW! Default expression levels for CYPs, UGTs, and sulfotransferases
  • Mechanistic In Vitro - In Vivo Correlation (IVIVC) for immediate or controlled release formulations (with optional IVIVCPlus™ Module)
  • Structure-based predictions of biopharmaceutical parameters required for GastroPlus simulations (with optional ADMET Predictor™ Module)
  • Automated pharmacodynamic model selection (PK/PD or PBPK/PD) with industry standard models (with optional PDPlus™ Module) 


GastroPlus Saves Time

As pharmaceutical, biotechnology, food ingredient, industrial chemical, and cosmetic companies strive to reduce the enormous costs and time required to bring new products to market, computer tools have become an important and necessary part of drug discovery and development. From simple spreadsheets to sophisticated supercomputer molecular dynamics models, the ability of researchers to experiment in silico has become an important complement to in vitro and in vivo experimentation. GastroPlus expands state-of-the-art computer simulation into the realm of absorption, pharmacokinetics, and pharmacodynamics.