Review
Foundation of Drug Pharmacokinetics and Application to Dosage Regimen
2006 Volume 19 Issue 2 Pages 111-123
Details
2006 Volume 19 Issue 2 Pages 111-123
It is generally considered that the intensity of the pharmacological effects and adverse effects of drug is determined by drug concentration in blood (plasma or serum) or the amount in the body. The therapeutic objective is to maintain a proper concentration of drug at the site of action during therapy. In addition, individual dosage adjustment based on targeted drug concentration in blood can prevent or minimize adverse effects of drug.
To administer drugs optimally, therefore, knowledge is needed not only of the mechanisms of drug absorption, distribution, metabolism and elimination but also of the kinetics of these processes, that is, pharmacokinetics. The pharmacokinetics is the study of the time course of the drug absorption, distribution, metabolism and excretion. If we can obtain the pharmacokinetic data (parameters) of drug following a single dose, the plasma concentration or amount of drug in the body at any dosing schedules can be mathematically estimated by the pharmacokinetic models. Knowing the pharmacokinetics of the drug aids the clinician in anticipating the optimal dosage regimen for individual patients and in predicting the pharmacological effects and adverse effects.
The most commonly used approach to the pharmacokinetic characterization of a drug is to represent the body as a compartment, and to assume that the rate of transfer between compartments and the rate of drug elimination from compartments follows the first-order kinetics. The one-compartment model, which represents the body as a single and kinetically homogeneous unit, is particularly useful for the pharmacokinetic analysis of drug.
In conclusion, basic pharmacokinetic theory in patients receiving drug therapy provides useful information to dosage adjustment for individual patients. This article describes about the application of therapeutic drug monitoring (TDM) in drug therapy, focusing upon the foundation of the pharmacokinetics of drug fitted to one-compartment model.
