Drugs administered through various routes can lead to nonlinear elimination, resulting in complex pharmacokinetic behaviors crucial to understanding efficacious drug dosing.
When a drug is administered through a constant intravenous infusion and eliminated via nonlinear pharmacokinetics, it follows zero-order input. For example, oral drugs undergo first-order absorption upon administration and are eliminated through nonlinear pharmacokinetics.
In the case of subcutaneously administered drugs, absorption from the dermis site into the blood gives rise to a two-compartment model featuring two distinct elimination processes. These processes encompass a saturable receptor-mediated elimination process in the bone marrow alongside a non-saturable elimination process through the kidneys.
Understanding the nuances of nonlinear drug elimination across different administration routes is essential for optimizing drug dosing regimens and ensuring therapeutic efficacy while minimizing the risk of adverse effects.
Drugs administered through different administration routes follow nonlinear elimination.
Consider a drug administered through a constant IV infusion, exemplifying zero-order input and eliminated by nonlinear pharmacokinetics. The following equation describes the rate of change in plasma drug concentration.
For instance, oral drugs are absorbed through first-order absorption and eliminated through nonlinear pharmacokinetics. It can be determined by the following equation.
Certain drugs are administered subcutaneously to get absorbed from the hypodermis site into the blood. These follow a two-compartment model with two elimination processes. A saturable process of receptor-mediated elimination in the bone marrow and a nonsaturable elimination process through the kidneys.
The model can be represented by two differential equations defined by respective Michaelis-Menten parameters.
Clearance of a drug may be considered as two parts. α is the function of dose with no dimensions and can take a value from 0 to 1.
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