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PharmD clinical pharmacy program Level 3, Semester 2 Biopharmaceutics & Pharmacokinetics (PT608(
Pharmacokinetic Models
After a drug is released from its dosage form, the drug is absorbed into the
surrounding tissue, the body, or both. The distribution through and elimination of
the drug in the body varies for each patient but can be characterized using
mathematical models and statistics.
A basic type of model used in pharmacokinetics is the compartmental model.
Compartmental models are categorized by the number of compartments needed
to describe the drug's behavior in the body. There are one-compartment, two-
compartment, and multi-compartment models.
There are other models such as non-compartment, catenary model……..etc.
The compartments do not represent a specific tissue or fluid but may represent a
group of similar tissues or fluids. These models can be used to predict the time
course of drug concentrations in the body. which, in turn, permits us to obtain
accurate estimates of the pharmacokinetics parameters such:
The apparent volume of drug distribution,
The elimination half-life and
The elimination rate constant of a drug.
which is the basis for the calculation of the dosage regimen (dose and dosing interval)
that will provide the desired plasma concentration and duration of action.
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