GastroPlusTM is an advanced technology computer program that simulates gastrointestinal absorption and pharmacokinetics, and optionally, pharmacodynamic effects, for drugs dosed orally and/or intravenously in humans and animals.
The mathematical model for the absorption/pharmacokinetic simulation accounts for:
- Physicochemical properties of the compound under study: lipophilicity, pKa’s, solubility, and effective permeability.
- The pH dependence of solubility, permeability, and dissolution/precipitation, including dissolution rates for different particle sizes when a particle size distribution is specified
- Formulation variables for both immediate release and controlled release dosage forms.
- Mixed multiple doses – combination of iv and peroral (PO) doses of arbitrary amounts at arbitrary times, and changing from fasted to fed states (or vice versa) at any time
- Physiological variables: pH’s, transit times, lengths, volumes, and enzyme and transporter protein (efflux and influx) distributions in the gut in different species.
- Chemical/metabolic degradation in the lumen.
- Variation in absorption/exsorption rate by concentration gradient, carrier-mediated transport (influx and efflux), and species.
- Up to 3-compartment pharmacokinetics including effects of first pass extraction (fixed or saturable), blood cell binding, and plasma protein binding.
- Optional physiologically based pharmacokinetics module (PBPKPlusTM) which can account for distribution, metabolism and general clearance in individual tissues.
The Virtual Trials feature in GastroPlusTM allows you to assess the combined effects of variations in population physiology and formulation variables that are not precise values, but for which distributions of values can be estimated.
The optional PDPlusTM module allows users to fit standard PD models proposed in literature to their observed PD data and to use the fitted PD models to evaluate changes in formulation.