GastroPlus program

More sophisticated approaches to predict the extent of oral absorption of drugs use mathematical models based on the known physiology and utilizing simple physicochemical measurements as input. The GastroPlus [4] program is a commercial tool that utilizes an advanced compartmental and transit model, based on the work of Amidon and Yu [5], and allows what-if questions to be posed to enable pharmaceutical optimization (see Chapter 17). For instance, the impact of morphology, formulation, and/or particle size changes, and sensitivity analysis to include errors in parameters on the prediction, can be considered. 

Figure 2. Estimation of DCS class based on the GastroPlus software of SimulationPlus. Based on the dimensionless Dose, Absorption and Dissolution Numbers, drugs can be defined as DCS Class 1 (A), 11 (B), 111 (C) and IV (D) based solely on structural information. The program gives predicted values for solubility, pKa and effective human intestinal permeability in order to suggest a fraction absorbed into the portal vein. (See color insert after Index.)...

The users of the GastroPlus 5.0 program (SimulationsPlus, Inc., Lancaster, CA) are provided with a series of methods for calculating partition coefficients for perfusion- and permeability-limited tissues, when running PBPK models. 

---