Pharmacokinetics Models

Pharmacokinetics (PK) models are generated to elucidate the transformations that a drug undergoes in an organism and the rules that determine this fate. Creative Biolabs develops a number of functional models to simplify the study of pharmacokinetics. PK model building is based on a number of related compartments (e.g. AUC).

Pharmacokinetics model is the central piece of model-based drug development. It is performed by noncompartmental or compartmental methods. Noncompartmental model is often estimated by AUC and other parameters, like C_max, C_min, and T_max. The closer time points are, the more accurate noncompartmental model reflects the actual shape of the concentration-time curve. Compartmental model is based on linear or nonlinear differential equations. The model relies on the kinetic model to describe and predict the concentration-time curve.

Creative Biolabs provides both noncompartmental and compartmental methods for PK model building. We also offer you service to transform published non-compartment model PK parameters into compartment model PK parameters.

Non-compartmental Modeling

Non-compartmental model thinks of an organism as only one homogenous compartment. It presumes that a drug's blood-plasma concentration is a true reflection of the concentration in other tissues and that the elimination of the drug is directly proportional to the drug's concentration in the organism. Non-compartmental methods are often more versatile, and it is acceptable for bioequivalence studies.

Creative Biolabs provides non-compartmental modeling analysis to calculate PK parameters. For instance, the area under the concentration (AUC) is calculated by the trapezoidal rule; clearance (CL) is calculated from drug dose and AUC; C_max and T_max are calculated from concentrations and time points; half-life is usually calculated from the last two to four sampling time-points directly. The closer time points are, the more accurate noncompartmental model reflects the actual shape of the concentration-time curve.

Compartmental Modeling

Compartmental modeling of pharmacokinetics describes the fate of a drug in the body by dividing the whole body into one or more compartments. A compartment involves several organs or tissues and is kinetically homogenous. Different compartments do not have a direct anatomical or physiological signification. In compartmental methods, drug concentration changes over time are estimated using kinetic models.

Creative Biolabs provides three types of compartmental models according to your need.

• Single-compartment model: The single-compartment model considers all of the organs and tissues to be one giant bucket: central compartment. The drug enters the central compartment from somewhere outside of the body and then leaves the central compartment. In this process, drug recirculation does not occur.
• Two-compartment model: In the two-compartment model, all the organs and tissues are divided into two compartments: central compartment and peripheral compartment. The plasma concentration of the drug appears to decay in a manner described by multiple exponential phases.
• Three-compartmental model: Three compartments are described: the central compartment (represents the plasma); the highly perfused compartment (represents the organs and tissues highly perfused by the blood); and the scarcely perfused compartment (represents the organs and tissues scarcely perfused by blood).

Creative Biolabs provides different ways to predict pharmacokinetic models of a drug. This allows a better prior adaptation of the dosage regimen of a drug in a particular situation.

For Research Use Only.